# Assistant conversation JRSBKB

- Canonical URL: <https://m.sheaf.less.rest/JRSBKB>
- Resource IRI: <https://m.sheaf.less.rest/JRSBKB>
- Type: assistant conversation
- Mode: chat

## Transcript

### 1. User

i wonder what to read generally to get good ideas about terrain boundaries like boulders and gravel and splash and beach and so on

### 2. Assistant tool calls

#### Tool call: `list_documents`

```json
{}
```

#### Tool call: `search_text`

```json
{
  "limit": 10,
  "query": "terrain boundary boulders gravel beach transition"
}
```

### 3. Tool result: list_documents

FOLDERS
- Accounting Algebra & Property Theory
- Assembly & Mechanism Ontology
- Discrete & Finite Element Exterior Calculus
- Graph-Theoretic & Compositional Systems Theory
- Living Structure, Wholeness & Beauty
- Living Structure, Wholeness &amp; Beauty
- ontology
- Procedural Generation & Co-Creation
- Roads, Trails & Movement
- Scenario-Based & Behavioral Programming
- Technology, Scale & Conviviality
- Terrain, Hydrology & Erosion
- Water Simulation & Rendering

Accounting Algebra & Property Theory (4)
- #GANFP9 A Fundamental Duality in the Mathematical and Natural Sciences: From Logic to Biology - 2024 | David Ellerman | 53 pp.
  Micro abstract: Traces an overlooked subset–partition duality—from logic and category theory through entropy and quantum indefiniteness to selectionist and generative mechanisms in biology.
- #NBH3BE Algebraic Models for Accounting Systems - 2010 | Derek J. S. Robinson, José García Pérez, Robert A. Nehmer, Salvador Cruz Rambaud | World Scientific | 255 pp.
  Micro abstract: Develops accounting theory algebraically: balance vectors as modules, transactions as a group, and whole accounting systems as automata with quotients, homomorphisms, and decision algorithms for audit and control.
- #7ESDBJ Economics, Accounting, and Property Theory - 1982 | David P. Ellerman | Lexington Books | 110 pp.
  Micro abstract: Ellerman's vector-accounting monograph: double entry generalized to property vectors ("accounting without valuation"), grounding a property-theoretic account of appropriation, the firm, and goodwill.
- #C8FHDZ On implication and negation in partition logic - 2025 |  , David Ellerman | Open Journal of Mathematical Sciences | 9 pp. | doi:10.30538/oms2025.0250
  Micro abstract: Develops implication as a refinement-sensitive operation on set partitions, showing how relative negation yields local Boolean cores within the non-distributive algebra of partitions.

Assembly & Mechanism Ontology (4)
- #6PYNP3 Object-Oriented Representation of Electro-Mechanical Assemblies Using UML - 2003 | Fujun Wang, Kevin W. Lyons, National Institute of Standards and Technology, Ram D. Sriram, Shaw C. Feng, Sudarsan Rachuri, Utpal Roy, Young-Hyun Han | NISTIR 7057 | 97 pp.
  Micro abstract: NIST report proposing the Open Assembly Model, a UML-based object-oriented representation for electro-mechanical assembly information exchange.
- #KSLF8E Ontology and Assembly Joint Topology Representation - 2008 | Kyoung-Yun Kim | Computer-Aided Design and Applications | 9 pp. | doi:10.3722/cadaps.2008.630-638
  Micro abstract: Uses mereotopology and SWRL rules to represent assembly joints as ontological relations, illustrated on a fixture assembly case study.
- #NHJEJG Representing Geometric Structures in d Dimensions: Topology and Order - 1993 | Erik Brisson | Proceedings of the fifth annual symposium on Computational geometry | 10 pp.
  Micro abstract: Formalizes geometric structures in d dimensions via combinatorial topology and order relations, a foundation for cell-complex representations used in assembly/geometric modeling.
- #KT87MS Towards an Ontology for Generative Design of Mechanical Assemblies - 2019 | Bahar Aameri, Hyunmin Cheong, J. Christopher Beck | Applied Ontology | 24 pp.
  Micro abstract: Proposes a formal ontology of mechanical assembly structure intended to support generative design systems.

Discrete & Finite Element Exterior Calculus (2)
- #AX2VJD Discrete Exterior Calculus - 2005 | Anil N. Hirani, Jerrold E. Marsden, Mathieu Desbrun, Melvin Leok | arXiv:math/0508341 | 53 pp.
  Micro abstract: Introduces discrete exterior calculus, a coordinate-free discretization of differential forms on simplicial complexes for computational modeling.
- #LTESUF Finite Element Exterior Calculus: From Hodge Theory to Numerical Stability - 2010 | Douglas N. Arnold, Ragnar Winther, Richard S. Falk | arXiv:0906.4325 / Bulletin of the AMS | 74 pp.
  Micro abstract: Surveys finite element exterior calculus, unifying Hodge theory and mixed finite element stability analysis for PDE discretization.

Graph-Theoretic & Compositional Systems Theory (4)
- #TA7A6Y Algebras of Open Dynamical Systems on the Operad of Wiring Diagrams - 2015 | David I. Spivak, Dmitry Vagner, Eugene Lerman | arXiv:1408.1598 | 26 pp.
  Micro abstract: Develops an operad-algebra formalism for open dynamical systems composed via wiring diagrams, underpinning compositional systems theory.
- #PB725Y Graph theoretic foundations of multibody dynamics - 2011 | Abhinandan Jain | Multibody System Dynamics | 35 pp. | doi:10.1007/s11044-011-9267-6
  Micro abstract: Second of a two-part paper deriving O(N) recursive algorithms (Newton-Euler, Lyapunov/Riccati factorizations) for multibody dynamics from the graph-theoretic spatial kernel/operator (SKO/SPO) models built in Part I.
- #RT6CVD Port-Hamiltonian Systems on Graphs - 2013 | A. J. van der Schaft, B. M. Maschke | SIAM Journal on Control and Optimization | 32 pp. | doi:10.1137/110840091
  Micro abstract: Builds port-Hamiltonian systems on open directed graphs via Dirac structures, unifying mass-spring-damper networks, spatial mechanisms, hydraulic networks, and consensus dynamics under one compositional geometric framework.
- #A6DBK8 Seven Sketches in Compositionality: An Invitation to Applied Category Theory - 2018 | Brendan Fong, David I. Spivak | 353 pp.
  Micro abstract: A textbook introducing applied category theory (orders, monoidal categories, operads, sheaves, etc.) through seven worked "sketches" connecting math to systems modeling.

Living Structure, Wholeness & Beauty (9)
- #MH5J8D Beautimeter: Harnessing GPT for Assessing Architectural and Urban Beauty Based on the 15 Properties of Living Structure - 2025 | Bin Jiang | AI | 12 pp. | doi:10.3390/ai6040074
  Micro abstract: Presents Beautimeter, a GPT-based tool that scores buildings and urban scenes against Christopher Alexander’s 15 properties of living structure to assess their coherence and beauty.
- #XW22YY Generative Codes: The Path to Building Welcoming, Beautiful, Sustainable Neighborhoods - 2005 | Brian Hanson, Christopher Alexander, Maggie Moore Alexander, Michael Mehaffy, Randall Schmidt | Center for Environmental Structure | 21 pp.
  Micro abstract: Argues that living neighborhoods arise from generative codes: ordered, participatory steps that let buildings and public spaces unfold from local people, land, and context.
- #SKRF4C Geography as a Science of the Earth’s Surface Founded on the Third View of Space - 2022 | Bin Jiang | Annals of GIS | 14 pp. | doi:10.1080/19475683.2021.1966502
  Micro abstract: Recasts geography around an organismic view of space, using scaling and spatial dependence to understand—and deliberately create—places with greater living structure.
- #PXG56P Harmony-Seeking Computations: A Science of Non-Classical Dynamics Based on the Progressive Evolution of the Larger Whole - 2009 | Christopher Alexander | Unpublished manuscript | 66 pp.
  Micro abstract: Proposes harmony-seeking computation as a creative process that repeatedly strengthens latent centers in a configuration while preserving and deepening the larger whole.
- #MJKTBB Living Images: A Recursive Approach to Computing the Structural Beauty of Images or the Livingness of Space - 2023 | Bin Jiang, Chris de Rijke | Annals of the American Association of Geographers | 19 pp. | doi:10.1080/24694452.2023.2178376
  Micro abstract: Measures an image’s structural beauty by recursively extracting its nested substructures, revealing a compact hierarchy that also captures visual saliency.
- #3XSLTA Structural Beauty: A Structure-Based Computational Approach to Quantifying the Beauty of an Image - 2021 | Bin Jiang, Chris de Rijke | Journal of Imaging | 15 pp. | doi:10.3390/jimaging7050078
  Micro abstract: Proposes a quantitative measure of structural beauty based on how many substructures an image contains and how strongly they form a hierarchy across scales.
- #ZU8GZV Structure-Preserving Transformations - 2002 | Christopher Alexander | The Nature of Order, Book Two: The Process of Creating Life | 4 pp. | doi:10.2307/j.ctv27ftw6c.5
  Micro abstract: Explains structure-preserving transformations: incremental changes that extend the centers and relationships already present in a place rather than weakening its wholeness.
- #AULNWD The Nature of Poetic Order - 1998 | Richard P. Gabriel | Warren Wilson Alumni Conference, Mount Holyoke | 99 pp.
  Micro abstract: Gabriel's slide essay relating poetry's formal order to Christopher Alexander's ideas of generative structure, exploring how constraint and pattern produce living order in creative work.
- #BYG3BQ Wholeness as a Hierarchical Graph to Capture the Nature of Space - 2015 | Bin Jiang | International Journal of Geographical Information Science | 14 pp. | doi:10.1080/13658816.2015.1038542
  Micro abstract: Models spatial wholeness as a hierarchical graph of mutually reinforcing centers, using PageRank and scaling depth to quantify the life of parts and wholes.

ontology (36)
- #LRK6E2 A Taxonomy of Granular Partitions - 2001 | Barry Smith, Thomas Bittner | Spatial Information Theory: Foundations of Geographic Information Science | 16 pp. | doi:10.1007/3-540-45424-1_3
  Micro abstract: Formalizes partitions as tree-structured cognitive devices projected onto reality, then classifies how accurately, structurally, and completely their cells recognize objects, with applications to cadastral and geographic data.
- #FQCWKV A Theory of Granular Partitions - 2003 | Barry Smith, Thomas Bittner | Foundations of Geographic Information Science | 33 pp.
  Micro abstract: Formalizes granular partitions as hierarchical cell systems projected onto reality, combining cognitive selectivity with mereological structure for naming, classifying, mapping, and representation.
- #SF7KYZ About the Unreal - 2025 | Barry Smith, Jim Logan, John Beverley | Proceedings of the Joint Ontology Workshops (JOWO), Episode XI | 14 pp.
  Micro abstract: Models fiction, blueprints, simulations, and other information about unreal entities through logical combinations of actual classes, avoiding commitments to nonexistent dummy instances.
- #CGE2NC Against Fantology - 2005 | Barry Smith | Experience and Analysis | 22 pp.
  Micro abstract: Critiques the idea that first-order logic reveals reality’s ontology, tracing its atomism, timelessness, Booleanism, and reductionism before proposing a six-category ontology and an enhanced Davidsonian formal language.
- #JZG4PM Against Fantology Again - 2016 | Ingvar Johansson | The Theory and Practice of Ontology | 12 pp.
  Micro abstract: Extends the critique of fantology through default ontologization, arguing that Quine’s canonical notation is incoherent about classes and excludes intentional phenomena and distinct modes of existence.
- #E5CLFY Agglomerations - 1999 | Barry Smith | Spatial Information Theory: Cognitive and Computational Foundations of Geographic Information Science | 16 pp. | doi:10.1007/3-540-48384-5_18
  Micro abstract: Defines agglomerations as geographically dispersed yet unified aggregates—populations, cultures, organizations, and diasporas—and develops a realist mereotopology for their boundaries, identity, and change.
- #3CCZ4A Bodily Systems and the Spatial-Functional Structure of the Human Body - 2004 | Barry Smith, Igor Papakin, Katherine Munn | Ontologies in Medicine | 26 pp. | doi:10.3233/978-1-60750-945-5-39
  Micro abstract: Integrates anatomy and physiology by modeling the body as a nested spatial-functional hierarchy whose parts are demarcated as system elements through the functions they bear and realize.
- #7YZU95 Boundaries: An Essay in Mereotopology - 1997 | Barry Smith | The Philosophy of Roderick Chisholm | 32 pp.
  Micro abstract: Reconstructs and extends the Brentano–Chisholm mereotopology in which dependent, coincident boundaries account for contact and the continuum across points, lines, surfaces, and bodies.
- #3TZK66 Capabilities: An Ontology - 2024 | Barry Smith, David Limbaugh, Eric Merrell, John Beverley, Peter M. Koch | Proceedings of the Joint Ontology Workshops (JOWO), Episode X | 14 pp.
  Micro abstract: Defines a capability as a disposition in whose realization an organism or group has or had an interest, placing capabilities between dispositions and functions in Basic Formal Ontology.
- #XYERFR Carving Up Reality - 2004 | Barry Smith | Categories: Historical and Systematic Essays | 14 pp.
  Micro abstract: Explains how context-sensitive, coarse-grained partitions guide reference and perception while preserving transitive parthood and distinguishing fiat demarcations from boundaries grounded in reality.
- #88BVY3 Categories in Top-Level Ontologies: Revisiting the Aristotelian Background - Barry Smith, Ludger Jansen | 31 pp.
  Micro abstract: Reconstructs Aristotle’s categories as the philosophical basis of BFO, extending the ontological square with processes into a six-category framework for continuants, occurrents, dependence, and multiple scientific granularities.
- #9G4F42 CLASSIFYING PROCESSES: AN ESSAY IN APPLIED ONTOLOGY - 2012 | Barry Smith | Ratio | 21 pp. | doi:10.1111/j.1467-9329.2012.00557.x
  Micro abstract: Extends Basic Formal Ontology to scientific process data through process profiles—quality, rate, and cyclical aspects that ground measurements, time-series graphs, and representations of dynamic systems.
- #GSLMP8 Diagrams, Documents, and the Meshing of Plans - 2013 | Barry Smith | Visual Learning, vol. 3: How to Do Things with Pictures: Skill, Practice, Performance | 14 pp.
  Micro abstract: Shows how diagrams and evolving networks of documents mesh plans, obligations, and specialized labor to enable coordinated collective action beyond the limits of linear text.
- #M8BQ3S Do Mountains Exist? Towards an Ontology of Landforms - 2003 | Barry Smith, David M. Mark | Environment and Planning B: Planning and Design | 22 pp.
  Micro abstract: Argues that mountains are object-like in everyday thought but elevation fields in environmental science, motivating a geospatial ontology that supports both perspectives.
- #KSESR8 Drawing Boundaries - 2019 | Barry Smith | The Philosophy of GIS | 26 pp. | doi:10.1007/978-3-030-16829-2_7
  Micro abstract: Updates the distinction between human-demarcated fiat boundaries and physically grounded bona fide boundaries, tracing its uses in geography, property, ecology, and Basic Formal Ontology.
- #56MWAA Environmental Metaphysics - 2001 | Achille C. Varzi, Barry Smith | Metaphysics in the Post-Metaphysical Age: Proceedings of the 22nd International Wittgenstein Symposium | 12 pp.
  Micro abstract: Develops an ontology of token niches as tenant–medium–retainer structures, using physical and fiat boundaries to explain environmental fit, protection, movement, and niche construction.
- #K6JC2J Layers: A New Approach to Locating Objects in Space - 2003 | Barry Smith, Maureen Donnelly | Spatial Information Theory: Foundations of Geographic Information Science | 16 pp. | doi:10.1007/978-3-540-39923-0_4
  Micro abstract: Extends mereotopology with layers that distinguish material objects, holes, and processes from the spatial and spatiotemporal regions they occupy, supporting dynamic geospatial reasoning beyond static map overlays.
- #KG5TBB Making space: the natural, cultural, cognitive and social niches of human activity - 2021 | Barry Smith | Cognitive Processing | 11 pp. | doi:10.1007/s10339-021-01049-y
  Micro abstract: Shows how legal decisions, plans, historical reasoning, and language create fiat spatial and spatiotemporal entities, then draws limits and practical lessons for ontology-supported AI.
- #FJ5KCA More Things in Heaven and Earth - 1995 | Barry Smith | Grazer Philosophische Studien | 15 pp.
  Micro abstract: Develops an ontology of spatial regions and boundaries, arguing that political territories are historically created fiat objects through performative maps while also recognizing vague, overlapping, and incomplete geographic objects.
- #KY3Y9U Naïve Physics: An Essay in Ontology - 1994 | Barry Smith, Roberto Casati | Philosophical Psychology | 22 pp. | doi:10.1080/09515089408573121
  Micro abstract: Reconstructs naïve physics as a realist ontology of the common-sense world—objects, processes, stuffs, boundaries, media, and values—drawing on Gestalt psychology and phenomenology to broaden AI’s set-theoretic models.
- #TQPVBD New Foundations for Qualitative Physics - 1990 | Barry Smith, Jean Petitot | Evolving Knowledge in Natural Science and Artificial Intelligence | 13 pp.
  Micro abstract: Argues for a scientific ontology of the qualitative common-sense world, using morphological discontinuities to connect physical substrates, sensible qualities, Aristotelian categories, and ecologically constrained cognition.
- #B98HVX Objects and Their Environments: From Aristotle to Ecological Ontology - 2001 | Barry Smith | The Life and Motion of Socio-Economic Units | 26 pp. | doi:10.1201/9781482268096-14
  Micro abstract: Extends Aristotelian substance–accident ontology into a realist theory of behavioral settings and ecological niches as nested, bounded wholes in which organisms, objects, and activities mutually fit.
- #9GWUC8 On Classifying Material Entities in Basic Formal Ontology - 2012 | Barry Smith | Interdisciplinary Ontology: Proceedings of the Third Interdisciplinary Ontology Meeting | 13 pp.
  Micro abstract: Clarifies BFO’s material entities by distinguishing objects, aggregates, and fiat object parts, and analyzes objects through causal unity by covering, physical forces, or engineered assembly without claiming exhaustivity.
- #KYQGNH On Credentials - 2020 | Barry Smith, Giuseppe Lorini, Olimpia Giuliana Loddo | Journal of Social Ontology | 21 pp. | doi:10.1515/jso-2019-0034
  Micro abstract: Provides a social ontology of credentials as portable, inspectable institutional documents that certify identity or status and give bearers the practical deontic power to exercise rights, with a typology of their forms and functions.
- #BV47YZ On Drawing Lines on a Map - 1995 | Barry Smith | Spatial Information Theory: A Theoretical Basis for GIS | 10 pp. | doi:10.1007/3-540-60392-1_31
  Micro abstract: Builds a typology of spatial boundaries around the fiat–bona fide distinction, applying it to maps, political and property divisions, scattered objects, linguistic framing, and truthmakers.
- #D8LRQM Ontological Foundations for Geographic Information Science - 2004 | Barry Smith, David M. Mark, Max J. Egenhofer, Stephen C. Hirtle | A Research Agenda for Geographic Information Science | 8 pp. | doi:10.1201/9781420038330.ch12
  Micro abstract: Sets a research agenda for geospatial ontology, linking formal accounts of geographic objects, processes, scale, and vagueness to human concepts, interoperable data, and ontology-driven GIS.
- #GN66WW Ontologies of Common Sense, Physics and Mathematics - 2023 | Barry Smith, Jobst Landgrebe | arXiv | 32 pp. | doi:10.48550/arXiv.2305.01560
  Micro abstract: Proposes linked upper ontologies for common sense, physics, and mathematics, arguing that classical models connect real magnitudes to mathematics whereas modern physics relates measurements to entities lacking commonsense universals.
- #WYP3G6 Ontology and Geographic Kinds - 1998 | Barry Smith, David M. Mark | Proceedings of the 8th International Symposium on Spatial Data Handling (SDH ’98) | 7 pp.
  Micro abstract: Argues that geographic kinds are intrinsically spatial and boundary-centered, requiring mereology and topology to connect physical reality, cultural categorization, cognition, and GIS representation.
- #9YMD2E SNAP and SPAN: Towards Dynamic Spatial Ontology - 2004 | Barry Smith, Pierre Grenon | Spatial Cognition & Computation | 35 pp. | doi:10.1207/S15427633SCC0401_5
  Micro abstract: BFO's bicategorial framework: SNAP snapshot ontologies of continuants and a SPAN ontology of processes in spacetime, linked by trans-ontological relations to capture change — demonstrated on the ontology of geodynamics.
- #KWFTKJ Surrounding Space: The Ontology of Organism-Environment Relations - 2002 | Achille C. Varzi, Barry Smith | Theory in Biosciences | 29 pp. | doi:10.1078/1431-7613-00053
  Micro abstract: Develops a formal ontology of token niches as tenant–medium–retainer structures, extending static organism–environment fit into a dynamic account of vacant niches, movement, interaction, and niche construction.
- #DLY2WP The Cognitive Geometry of War - 1997 | Barry Smith | Current Issues in Political Philosophy: Justice in Society and World Order | 26 pp.
  Micro abstract: Argues that modern ideals of compact, contiguous national territory help drive conflict, and proposes perforated, non-contiguous, and geometrically flexible borders as alternatives to displacement and ethnic cleansing.
- #4QQD4A The Logic of Systems of Granular Partitions - 2005 | Barry Smith, Maureen Donnelly, Thomas Bittner | IFOMIS Reports | 23 pp.
  Micro abstract: Builds a sound S4-style modal logic for labeled, typed granular partitions, modeling refinement and cross-partition counterparts so differently selective views can reason about the same mereologically structured reality.
- #2F8T3H Toward a Realistic Science of Environments - 2009 | Barry Smith | Ecological Psychology | 11 pp.
  Micro abstract: Defends Gibsonian ecological realism: organisms directly perceive affordances in physically real niches, while granular partitions show how different species inhabit perspectives on one world, not separate constructed worlds.
- #DT9Y7X True Grid - 2002 | Barry Smith | Spatial Information Theory: Foundations of Geographic Information Science | 17 pp.
  Micro abstract: Generalizes Alberti’s perspectival grid into a realist theory of projection: pictures, maps, names, concepts, and databases are “true grids” when their cells preserve relevant structure and refer transparently to reality.
- #PHAFYA Truth and the Visual Field - 1997 | Barry Smith | Naturalizing Phenomenology: Issues in Contemporary Phenomenology and Cognitive Science | 8 pp.
  Micro abstract: Uses mereotopology and Gibsonian ecology to treat perception and language as carving transient fiat boundaries in reality, defining a judgment field as the truth-making portion of the world selected by a true sentence.
- #XZX6PE Vague Reference and Approximating Judgments - 2003 | Barry Smith, Thomas Bittner | Spatial Cognition and Computation | 20 pp.
  Micro abstract: Formalizes vague reference as multiple crisp candidate referents within granular partitions, then explains approximation as using familiar spatial or temporal reference grids to constrain vagueness without truth-value indeterminacy.

Procedural Generation & Co-Creation (14)
- #ABD2B8 Between Tech and Art: The Vegetation of Horizon Zero Dawn - 2018 | Gilbert Sanders, Guerrilla Games | Game Developers Conference (GDC) 2018 | 87 pp.
  Micro abstract: A production breakdown of Horizon Zero Dawn’s vegetation pipeline, covering global wind simulation, layered foliage motion, coverage-preserving alpha mipmaps, shading, asset LODs, placement, and cascaded shadows.
- #4TH488 Explainable AI for Designers: A Human-Centered Perspective on Mixed-Initiative Co-Creation - 2018 | Antonios Liapis, G. Michael Youngblood, Jichen Zhu, Rafael Bidarra, Sebastian Risi | 2018 IEEE Conference on Computational Intelligence and Games (CIG) | 8 pp. | doi:10.1109/CIG.2018.8490433
  Micro abstract: Defines explainable AI for game designers, mapping co-creative systems by their explainability, initiative, and domain overlap so explanations serve concrete design tasks.
- #9NQ94D Extracting Physics from Blended Platformer Game Levels - 2020 | Adam Summerville, Anurag Sarkar, Joseph C. Osborn, Sam Snodgrass | Joint Proceedings of the AIIDE 2020 Workshops (CEUR Workshop Proceedings, Vol. 2862) | 7 pp.
  Micro abstract: Infers playable jump physics from generated platformer levels, including hybrid physics models for levels that blend the geometry and style of multiple games.
- #66Q3W3 Ghost of Tsushima: Procedural Grass - 2021 | Eric Wohllaib, Sucker Punch Productions | Game Developers Conference (GDC) 2021 | 55 pp.
  Micro abstract: Explains Ghost of Tsushima’s compute-driven grass pipeline, from tiled placement and culling to indirect drawing, cubic Bézier blade geometry, variable LOD, wind animation, and material shading.
- #QHMFH2 Improved Alpha Testing Using Hashed Sampling - 2019 | Chris Wyman, Morgan McGuire | IEEE Transactions on Visualization and Computer Graphics | 12 pp. | doi:10.1109/TVCG.2017.2739149
  Micro abstract: Develops hashed alpha testing, a stable quasi-random thresholding method that preserves distant alpha-mapped foliage and hair while controlling flicker, anisotropy, and interactions with TAA and alpha-to-coverage.
- #7GR3AQ Procedural Content Generation through Quality Diversity - 2019 | Ahmed Khalifa, Antonios Liapis, Daniele Gravina, Georgios N. Yannakakis, Julian Togelius | 2019 IEEE Conference on Games (CoG) | 8 pp. | doi:10.1109/CIG.2019.8848053
  Micro abstract: Argues for quality-diversity algorithms in procedural generation, producing broad collections of varied, playable content while exposing the design space for exploration and co-creation.
- #CQBDX4 Procedural Content Generation via Machine Learning (PCGML) - 2018 | Aaron Isaksen, Adam Summerville, Amy K. Hoover, Andy Nealen, Christoffer Holmgård, Julian Togelius, Matthew Guzdial, Sam Snodgrass | IEEE Transactions on Games | 15 pp. | doi:10.1109/TG.2018.2846639
  Micro abstract: Defines and surveys PCGML: generating functional game content directly from models trained on existing examples, with uses spanning creation, completion, repair, critique, and compression.
- #EARFEK Procedural Generation of Villages on Arbitrary Terrains - 2012 | Adrien Bernhardt, Adrien Peytavie, Arnaud Emilien, Eric Galin, Marie-Paule Cani | The Visual Computer | 10 pp. | doi:10.1007/s00371-012-0699-7
  Micro abstract: Presents a three-stage procedural model that grows terrain-responsive village roads and settlements, partitions land into plausible parcels, and generates slope-adapted buildings with open shape grammars.
- #EDURTK Real-Time GPU Tree Generation - 2025 | Bastian Kuth, Carsten Faber, Dominik Baumeister, Max Oberberger, Pirmin Pfeifer, Quirin Meyer, Seyedmasih Tabaei | High-Performance Graphics – Symposium Papers | 10 pp. | doi:10.2312/hpg.20251168
  Micro abstract: Introduces a GPU work-graph pipeline that generates, animates, edits, and continuously LODs detailed seasonal trees every frame, replacing gigabytes of baked geometry with kilobytes of parameters.
- #GBXEP3 Realistic Modeling and Rendering of Plant Ecosystems - 1998 | Bernd Lintermann, Matt Pharr, Oliver Deussen, Pat Hanrahan, Przemyslaw Prusinkiewicz, Radomír Měch | Proceedings of SIGGRAPH ’98 | 12 pp. | doi:10.1145/280814.280898
  Micro abstract: Presents a foundational pipeline for authoring plant ecosystems through terrain design, ecological simulation, procedural plant models, approximate instancing, and efficient rendering of billion-primitive scenes.
- #BDBBL6 Real‐time Realistic Rendering and Lighting of Forests - 2012 | Eric Bruneton, Fabrice Neyret | Computer Graphics Forum | 11 pp. | doi:10.1111/j.1467-8659.2012.03016.x
  Micro abstract: Combines detailed z-field trees with terrain shader-maps to render immense forests in real time, preserving sun, sky, canopy, and ground-lighting effects through seamless, scale-consistent transitions.
- #PQ68ZH Responsive Real-Time Grass Rendering for General 3D Scenes - 2017 | Klemens Jahrmann, Michael Wimmer | Proceedings of the 2017 Symposium on Interactive 3D Graphics and Games (I3D ’17) | 10 pp. | doi:10.1145/3023368.3023380
  Micro abstract: Renders every grass blade as responsive tessellated geometry on arbitrary 3D surfaces, with per-blade wind, gravity, and collision physics plus aggressive culling that retains dense fields in real time.
- #WZ8DHP Runtime Evaluation of Procedural Content Generation in an Endless Runner Game Using Autonomous Agents - 2026 | Rishabh Kar | arXiv | 25 pp. | doi:10.48550/arXiv.2605.01783
  Micro abstract: Integrates procedural generation and validation in an endless runner, using aerial and ground agents to detect blocked or unnavigable content before the player reaches it.
- #NRBMD5 Towards Friendly Mixed Initiative Procedural Content Generation: Three Pillars of Industry - 2020 | Frederic Fol Leymarie, Gorm Lai, William Latham | Proceedings of the International Conference on the Foundations of Digital Games (FDG '20) | 4 pp. | doi:10.1145/3402942.3402946
  Micro abstract: Distills three requirements for industry-friendly co-creative PCG tools: preserve designer control, keep feedback loops short, and fit into existing production pipelines.

Roads, Trails & Movement (8)
- #G3TBNG A Sequential Two-Step Algorithm for Fast Generation of Vehicle Racing Trajectories - 2016 | J. Christian Gerdes, John Subosits, Nitin R. Kapania | Journal of Dynamic Systems, Measurement, and Control | 12 pp. | doi:10.1115/1.4033311
  Micro abstract: Generates near-optimal racing trajectories quickly by alternating between a minimum-time speed profile and a convex path update that reduces curvature.
- #B6P8L4 Active walker model for the formation of human and animal trail systems - 1997 | Dirk Helbing, Frank Schweitzer, Joachim Keltsch, Péter Molnár | Physical Review E | 34 pp. | doi:10.1103/physreve.56.2527
  Micro abstract: Models trail systems as self-organization: walkers reinforce attractive routes while unused traces fade, producing dendritic ant trails and low-detour pedestrian networks.
- #V4TQYB Interactive procedural street modeling - 2008 | Eugene Zhang, Gregory Esch, Guoning Chen, Pascal Müller, Peter Wonka | ACM Transactions on Graphics | 10 pp. | doi:10.1145/1360612.1360702
  Micro abstract: Lets designers generate and edit large street networks through tensor fields, combining procedural speed with brush-like global and local control over street patterns.
- #UYLTYJ Modelling the Evolution of Human Trail Systems - 1997 | Dirk Helbing, Joachim Keltsch, Péter Molnár | Nature | 11 pp. | doi:10.1038/40353
  Micro abstract: Shows how pedestrian trails emerge through feedback between destination-seeking walkers, existing paths, and vegetation recovery, yielding a compromise between directness and shared infrastructure.
- #GY93FG Mountain Trail Formation and the Active Walker Model - 2009 | J. P. Hague, S. J. Gilks | International Journal of Modern Physics C | 22 pp. | doi:10.1142/S0129183109014059
  Micro abstract: Extends the active-walker model to steep terrain, explaining zigzag mountain trails through slope avoidance, directional persistence, and mutual reinforcement by ascending and descending walkers.
- #LXV9AT Principles of Trail Layout and Design - 2019 | California State Parks | California State Parks Trails Handbook | 64 pp.
  Micro abstract: A field-oriented guide to durable trail design, emphasizing curvilinear alignment, natural drainage, sustainable grades, control points, and close reading of landform and soils.
- #XDEFZS Procedural Generation of Roads - 2010 | A. Peytavie, E. Galin, E. Guérin, N. Maréchal | Computer Graphics Forum | 10 pp. | doi:10.1111/j.1467-8659.2009.01612.x
  Micro abstract: Automatically routes and constructs roads with an anisotropic shortest-path method that weighs slope and obstacles while treating surface segments, bridges, and tunnels consistently.
- #ARP5U7 The Topography of Minoan Peak Sanctuaries - 1983 | A. A. D. Peatfield | The Annual of the British School at Athens | 8 pp. | doi:10.1017/s0068245400019729
  Micro abstract: Argues that Minoan peak sanctuaries were chosen for visibility and proximity to local settlements, forming a beacon-like sacred network whose contraction tracked settlement abandonment rather than cultic collapse.

Scenario-Based & Behavioral Programming (8)
- #P2W4J5 Adaptive Behavioral Programming - 2011 | David Harel, Nir Eitan | 8 pp. | doi:10.1109/ictai.2011.109
  Micro abstract: Adds reinforcements to live sequence charts and BPJ so scenario-based programs can learn from their environment, specifying goals to pursue and scenarios to avoid, with modular learning decompositions.
- #XQ5NKX Challenges in Modeling and Unmodeling Emergence, Rule Composition, and Networked Interactions in Complex Reactive Systems - 2023 | Assaf Marron, David Harel, Guy Frankel, Irun Cohen, Smadar Szekely | 8 pp. | doi:10.5220/0011728900003402
  Micro abstract: Position paper on modeling emergence, rule composition, and networked interactions in complex reactive systems, introducing "unmodeling"—explicitly excluding entities and behaviors from model execution.
- #D4VB7S Distributing Scenario-Based Models: A Replicate-and-Project Approach - 2017 | Assaf Marron, Daniel Gritzner, David Harel, Guy Katz, Joel Greenyer, Shlomi Steinberg | MODELSWARD 2017 | 16 pp. | doi:10.5220/0006271301820195
  Micro abstract: Distributes scenario-based models by replicating the full specification on every component and projecting it per component, mimicking centralized behavior while sharply reducing synchronization.
- #CSJARA Enhancing Scenario-Based Modeling Using Large Language Models - 2026 | Assaf Marron, David Harel, Guy Katz, Smadar Szekely | Communications in Computer and Information Science | Springer Nature Switzerland | pp. 43-68 | 26 pp. | doi:10.1007/978-3-031-96841-9_3
  Micro abstract: Extended methodology for combining LLM chatbots with scenario-based modeling: iterative generation of stand-alone scenarios checked by analysis and human review, framed as a step toward Wise Computing.
- #3JCRAD On Augmenting Scenario-Based Modeling with Generative AI - 2024 | Assaf Marron, David Harel, Guy Katz, Smadar Szekely | MODELSWARD 2024 | 12 pp. | doi:10.5220/0012427100003645
  Micro abstract: Outlines a structured method for using generative-AI chatbots in modeling: iteratively generate scenario-based model fragments, then analyze and inspect them to converge on an accurate system model.
- #QV3BWZ On tracing reactive systems - 2011 | David Harel, Shahar Maoz | Software &amp; Systems Modeling | 22 pp. | doi:10.1007/s10270-010-0151-2
  Micro abstract: Introduces model-based trace visualization and exploration for reactive systems, using scenario-based (LSC) abstractions and the Tracer prototype, demonstrated on a PacMan game.
- #TDS4H2 Relaxing Synchronization Constraints in Behavioral Programs - 2013 | Amir Kantor, David Harel, Guy Katz | LPAR 2013 (Logic for Programming, Artificial Intelligence, and Reasoning) | 17 pp. | doi:10.1007/978-3-642-45221-5_25
  Micro abstract: Proposes eager execution for behavioral programs: fast b-threads run ahead when synchronization outcomes are predictable, improving performance, modularity, and distributability, shown in a C++ BP framework.
- #M5788P Towards Behavioral Programming in Distributed Architectures - 2015 | Amir Kantor, Assaf Marron, David Harel, Gera Weiss, Guy Katz, Guy Wiener | Science of Computer Programming | 58 pp. | doi:10.1016/j.scico.2014.03.003
  Micro abstract: Extends behavioral programming to distributed architectures: b-threads as Erlang processes, eager execution to relax synchronization, and modular distributed execution, demonstrated on simulations and a quadrotor.

Technology, Scale & Conviviality (2)
- #WYH36B The City as Convivial Centre - 1974 | Leopold Kohr | Tract, no. 12 (Gryphon Press) | 18 pp.
  Micro abstract: Kohr's essay arguing that cities exist for convivial life rather than economic function, and that human-scale size is what lets a city serve as a centre of leisure, culture, and encounter.
- #67REFX The Question Concerning Technology - 1977 | Martin Heidegger | The Question Concerning Technology and Other Essays (Harper & Row) | 23 pp.
  Micro abstract: Heidegger's essay on the essence of technology as Enframing (Gestell), a mode of revealing that reduces the world to standing-reserve, and on art as a possible saving power.

Terrain, Hydrology & Erosion (8)
- #NV2YRW FastFlow: GPU Acceleration of Flow and Depression Routing for Landscape Simulation - 2024 | Aryamaan Jain, Bernhard Kerbl, Brandon Finley, Guillaume Cordonnier, James Gain | Computer Graphics Forum | 13 pp. | doi:10.1111/cgf.15243
  Micro abstract: A GPU framework for routing surface flow through terrain and its depressions fast enough to make erosion, river, lake, and ecosystem simulations interactive.
- #2284QZ From features to fingerprints: A general diagnostic framework for anthropogenic geomorphology - 2019 | Damian Evans, Erle C Ellis, Giulia Sofia, Paolo Tarolli, Wenfang Cao | Progress in Physical Geography: Earth and Environment | 34 pp. | doi:10.1177/0309133318825284
  Micro abstract: Integrates geomorphology, archaeology, and high-resolution remote sensing into a framework for reading anthropogenic landforms as landscape-scale sociocultural fingerprints.
- #96ZMGK Large Scale Terrain Generation from Tectonic Uplift and Fluvial Erosion - 2016 | Adrien Peytavie, Bedrich Benes, Guillaume Cordonnier, Jean Braun, Marie-Paule Cani, Éric Galin, Éric Guérin | Computer Graphics Forum | 11 pp. | doi:10.1111/cgf.12820
  Micro abstract: Generates large, controllable mountain terrains by coupling user-painted tectonic uplift with fluvial erosion, then turning the resulting stream graph into detailed landforms.
- #K82AS7 Legacy sediment: Definitions and processes of episodically produced anthropogenic sediment - 2013 | L. Allan James | Anthropocene | 11 pp. | doi:10.1016/j.ancene.2013.04.001
  Micro abstract: Broadens legacy sediment to episodically produced anthropogenic alluvium and colluvium, and explains its deposition, storage, and remobilization through sediment delivery–transport capacity dynamics.
- #DWXKYQ Physically-based analytical erosion for fast terrain generation - 2024 | Boris Gailleton, Guillaume Cordonnier, Petros Tzathas, Philippe Steer | Computer Graphics Forum | 14 pp. | doi:10.1111/cgf.15033
  Micro abstract: Turns the stream power law into an interactive terrain tool, replacing thousands of erosion time steps with analytical solutions and a direct control for landscape age.
- #MTDKDE Priority-Flood: An Optimal Depression-Filling and Watershed-Labeling Algorithm for Digital Elevation Models - 2014 | Clarence Lehman, David Mulla, Richard Barnes | Computers & Geosciences | 17 pp. | doi:10.1016/j.cageo.2013.04.024
  Micro abstract: Introduces Priority-Flood, a simple, optimal algorithm that removes drainage-blocking depressions from elevation models and can also derive watersheds and flow directions.
- #AK7NGE Procedural Riverscapes - 2019 | A. Peytavie, B. Benes, E. Galin, E. Guérin, J. Gain, T. Dupont, Y. Cortial | Computer Graphics Forum | 12 pp. | doi:10.1111/cgf.13814
  Micro abstract: Builds editable, animated riverscapes from bare terrain by carving hydrologically plausible channels and blending real-time procedural water primitives instead of simulating fluids.
- #DMTA8Y Terrain Generation Using Procedural Models Based on Hydrology - 2013 | Adrien Peytavie, Bedřich Beneš, Jean-David Génevaux, Éric Galin, Éric Guérin | ACM Transactions on Graphics | 10 pp. | doi:10.1145/2461912.2461996
  Micro abstract: Generates controllable, multiscale terrain from a sketched drainage network, representing rivers and landforms as an editable hierarchy of continuous procedural primitives.

Water Simulation & Rendering (12)
- #RBS5K6 A Layered Particle-Based Fluid Model for Real-Time Rendering of Water - 2010 | Daniel Scherzer, Florian Bagar, Michael Wimmer | Computer Graphics Forum | 7 pp. | doi:10.1111/j.1467-8659.2010.01734.x
  Micro abstract: Renders particle-based water and volumetric foam in real time using perspective-aware surface smoothing, physically guided foam formation, and layered depth compositing.
- #C4AY2M A Survey of Ocean Simulation and Rendering Techniques in Computer Graphics - 2011 | B. Crespin, D. Ghazanfarpour, E. Darles, J.-C. Gonzato | Computer Graphics Forum | 17 pp. | doi:10.1111/j.1467-8659.2010.01828.x
  Micro abstract: Surveys ocean graphics from spectral deep-water models to near-shore fluid simulation, then covers the foam, spray, and light transport needed for convincing rendering.
- #WZMZGY Advected river textures - 2009 | Dirk Arnold, Stephen Brooks, Tim Burrell | Computer Animation and Virtual Worlds | 11 pp. | doi:10.1002/cav.288
  Micro abstract: Combines a 2D Navier–Stokes solver, hydrostatic pressure columns, and advected procedural textures to render detailed, terrain-responsive rivers at real-time frame rates.
- #92XRH7 Lagrangian Texture Advection: Preserving both Spectrum and Velocity Field - 2011 |  Qizhi Yu, E. Bruneton, F. Neyret, N. Holzschuch | IEEE Transactions on Visualization and Computer Graphics | 13 pp. | doi:10.1109/tvcg.2010.263
  Micro abstract: Advects fluid textures with deformable particle grids, preserving both the input texture’s visual spectrum and exact motion along the velocity field without cumulative stretching.
- #8SERGP Real-time Breaking Waves for Shallow Water Simulations - 2007 | Markus Gross, Matthias Müller-Fischer, Nils Thürey, Simon Schirm | 15th Pacific Conference on Computer Graphics and Applications (Pacific Graphics 2007) | 8 pp. | doi:10.1109/PG.2007.33
  Micro abstract: Adds real-time overturning waves to shallow-water heightfields by detecting steep fronts and spawning connected particle sheets that collapse into splashes and foam.
- #CWC7H9 Real-time Rendering of Enhanced Shallow Water Fluid Simulations - 2013 | Antonio Susín, Jesús Ojeda | Computers & Graphics | 9 pp.
  Micro abstract: Builds a real-time rendering pipeline for shallow-water simulations, adding fine surface detail, advected foam, photon-based caustics, and screen-space reflection and refraction.
- #MVUJ8Z Real-time Rendering of River Networks - 2010 | Quintijn Hendrickx, Rafael Bidarra, Ruben M. Smelik | Proceedings of the ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games | 1 pp.
  Micro abstract: Renders branching river networks efficiently with quadratic Bézier curves, GPU distance fields, and streaming normal maps instead of dense geometry or particle simulation.
- #5MGCZ5 Real-time River Representation by Dynamic Control of Data on Waves - 2008 | Makoto Kosugi, Nobuhiko Mukai, Yasuhiro Kato | 4 pp. | doi:10.3169/itej.62.2063
  Micro abstract: Dynamically switches river-wave models by viewing distance, preserving nearby reflection and wave detail while retaining wind-driven motion across the full landscape.
- #XDESU9 Scalable real‐time animation of rivers - 2009 | Eric Bruneton, Fabrice Neyret, Nicolas Holzschuch, Qizhi Yu | Computer Graphics Forum | 11 pp. | doi:10.1111/j.1467-8659.2009.01363.x
  Micro abstract: Animates rivers across vast terrains by computing steady flow locally and advecting fine surface detail only where visible, at a screen-space sampling density.
- #869NHK Very Fast Real-Time Ocean Wave Foam Rendering Using Halftoning - 2011 | Ian Parberry, Jennifer R. Alford, Mary Yingst | Proceedings of the 6th International North American Conference on Intelligent Games and Simulation (GAMEON-NA) | 7 pp.
  Micro abstract: Uses a spectrally controlled halftone mask to make texture-based ocean foam dissipate as clumped bubbles that pop, rather than merely fading transparently.
- #A2QB8L Water Flow in Portal 2 - 2010 | Alex Vlachos | ACM SIGGRAPH 2010 Course: Advances in Real-Time Rendering in 3D Graphics and Games | 54 pp.
  Micro abstract: Explains Portal 2’s production-friendly water shader: artist-painted flow maps advect layered normal maps, while offsets and noise suppress repetition and pulsing on limited hardware.
- #PBM2TC Water surface wavelets - 2018 | Chris Wojtan, Matthias Müller-Fischer, Miles Macklin, Nuttapong Chentanez, Stefan Jeschke, Tomáš Skřivan | ACM Transactions on Graphics | 13 pp. | doi:10.1145/3197517.3201336
  Micro abstract: Represents water waves as spatially varying directional amplitudes, enabling vast interactive simulations with fine detail, moving obstacles, solid coupling, and direct artistic control.

Unfiled (1)
- #3CV92Z moppe

### 4. Tool result: search_text

Exact matches

1. Source: Real‐time Realistic Rendering and Lighting of Forests (#BDBBL6), Eric Bruneton, Fabrice Neyret, p. 7
  Context:
    #ZX2JYE Real-time Realistic Rendering and Lighting of Forests
      #5KNTTV 7. Seamless transition between representations
  Matching excerpt #HWH7E9:
      4 color components (tree vs ground, lit vs unlit) are computed on a statistical basis and thus cannot match a given tree instance. This would give a visible color discontinuity at the transition. Third, our shader-map model neglects forest thickness. Even if we use it when trees are at most 3 pixels tall, this would yield popping on the terrain silhouettes. To solve these problems, we propose a seamless transition scheme divided in three parts: one transition inside each representation, and a transition between them.

2. Source: Real‐time Realistic Rendering and Lighting of Forests (#BDBBL6), Eric Bruneton, Fabrice Neyret, p. 7
  Context:
    #ZX2JYE Real-time Realistic Rendering and Lighting of Forests
      #5KNTTV 7. Seamless transition between representations
  Matching excerpt #X9PHPN:
      Transition between representations. To avoid popping on the terrain silhouettes, we progressively fade out the trees rendered with our z-field tree representation. For this, we multiply the opacity \alpha_v with 1 - \text{smoothstep}(0.8, 1, s/s_{max}) , while replacing the ground radiance in this transition region with our forest radiance model, modified as follows:

3. Source: Physically-based analytical erosion for fast terrain generation (#DWXKYQ), Boris Gailleton, Guillaume Cordonnier, Petros Tzathas, Philippe Steer, p. 11
  Context:
    #JDHNVB Physically-based analytical erosion for fast terrain generation
      #PZFF56 7. Results
        #V6AZDH 7.3. Applicability of our method
  Matching excerpt #RKFYWV:
      Canyons , especially the well-known examples such as the Grand Canyon , do not exhibit the large flat-bottomed areas between the cliffs observed in Figure 12. The difference comes from the boundary conditions: our results in Figure 12 assumed a flat boundary condition, while a canyon is typically tributary to another river downstream. To implement this, we assume a constant a = a(0) to extend D_{x,t} negatively beyond the bound and we assume a constant slope to deduce z_0(D_{x,t}) . We illustrate the impact of this new boundary condition in Figure 13 where we set a single boundary node to which we assign this small slope boundary condition . We additionally set a source point on the other side of the terrain where we impose a strong drainage area A to enforce the formation of a main river connecting these two points. Erosion at time t = 700ky shows a fully formed canyon with multiple tributary rivers branching out. Note that the new boundary condition resulted in the desired V-shaped walls surrounding the main river.

4. Source: Ontology and Geographic Kinds (#WYP3G6), Barry Smith, David M. Mark, p. 4
  Context:
    #PL2PE5 Ontology and Geographic Kinds
      #Z8DMWN 5 The Realm of Fiats
        #PY5FSP 5.6 Fiats in the realm of concepts
  Matching excerpt #W5DSFW:
      In this fashion counterparts of the familiar topological notions of boundary, interior, contact, separation, and continuity can be defined for the conceptual realm, and the notion of similarity as a relation between instances can be understood as a topological notion (Mostowski 1983; Petitot, 1994). In the realm of colors, for example, a is similar to b might be taken to mean that the colors of a and b lie so close together in color-space that they cannot be discriminated with the naked eye. A similarity relation is in general symmetric and reflexive, but it falls short of transitivity, and is thus not an equivalence relation. This means that it partitions the space of instances not into tidily disjoint and exhaustive equivalence classes, but rather into overlapping circles of similars. This falling short of the discreteness and exhaustiveness of partitions of the type that are generated by equivalence relations is characteristic of topological structures. In some cases, there is a continuous transition from one concept to its neighbors in concept-space, as for example in the transition from lake to marsh to wetland. In other cases, circles of similars are separated by gaps (regions of concept-space that have no instances). This is so regarding the transition from, say, lake to reservoir.

5. Source: Scalable real‐time animation of rivers (#XDESU9), Eric Bruneton, Fabrice Neyret, Nicolas Holzschuch, Qizhi Yu, p. 3
  Context:
    #B9LYTR Scalable real-time animation of rivers
      #XF2N2Y 3. Overview
  Matching excerpt #ZHHTDN:
      Rendering. We render the fluids by rendering meshes on top of the terrain. The meshes are created from the channel boundary curves. They are rendered with a shader that recovers and blends together the wave sprites that overlap each pixel (see Section 5.2).

6. Source file: moppe/shaders/metal/terrain.metal
   Resource: https://m.sheaf.less.rest/3CV92Z/source-files/bW9wcGUvc2hhZGVycy9tZXRhbC90ZXJyYWluLm1ldGFs#content
   Size: 46211 bytes, 977 lines
   Matching excerpt:
      // Terrain: vertex-pulled from the height/normal textures (no vertex // buffers), splat-textured by altitude and slope, PCF-shadowed. // Port of shaders/test.vert + test.frag with explicit uniforms. // // The height texture is R32Float and is accessed via integer read(). // R32F is not linearly filterable on Apple GPUs before Apple9, so the // subdivided near field performs its four-tap interpolation manually. #include "common.h" struct TerrainVaryings { float4 position [[position]]; float3 world_pos; float3 normal; // world space float height; // altitude in metres float fog; // haze factor incl. valley mist float4 shadow_coord; float2 uv; float2 field_uv; float2 grid_coord; // authoritative source-height lattice float2 mesh_coord; // actual rendered lattice float lod_step [[flat]]; // source texels per rendered grid edge }; // Catmull-Rom reconstruction and its derivative. The final 2D height is // kept within the four corners of the source cell, so smoothing cannot grow a // new peak or dig a new pit between authoritative height samples. static inline float2 terrain_cubic (float p0, float p1, float p2, float p3, float t) { const float a = 0.5 * (-p0 + 3.0 * p1 - 3.0 * p2 + p3); 
   Read the complete file with read blocks=["https://m.sheaf.less.rest/3CV92Z/source-files/bW9wcGUvc2hhZGVycy9tZXRhbC90ZXJyYWluLm1ldGFs#content"]

7. Source file: planning/tracks/current-engine-refactoring/items/ENG-002-characterize-refactoring-seams.md
   Resource: https://m.sheaf.less.rest/3CV92Z/source-files/cGxhbm5pbmcvdHJhY2tzL2N1cnJlbnQtZW5naW5lLXJlZmFjdG9yaW5nL2l0ZW1zL0VORy0wMDItY2hhcmFjdGVyaXplLXJlZmFjdG9yaW5nLXNlYW1zLm1k#content
   Size: 1249 bytes, 37 lines
   Matching excerpt:
      +++ id = "ENG-002" title = "Characterize the world, surface, and replay seams before moving them" rfc = "RFC-0001" track = "current-engine-refactoring" status = "done" depends_on = ["ENG-001"] order = 20 areas = ["tests", "map", "game"] +++ # Characterize the world, surface, and replay seams before moving them ## Outcome The existing behavior at the intended refactoring boundaries is captured by small tests and deterministic artifacts. ## Scope Surface sampling parity, materialization barriers, fixed-step state restore, and the completed-world loading transition. This is characterization, not a new golden corpus for every subsystem. ## Acceptance - Tests fail if a moved boundary changes its observable contract. - A smoke path reaches a generated world rather than stopping at loading. - Any newly captured golden has an explicit owner and update policy. ## Evidence `docs/refactoring-seams.md` assigns the existing focused tests to the surface, terrain-checkpoint, and running-state contracts. `tools/capture-water` reached a generated river world with its fixed seed/profile inputs. The capture is a smoke artifact, not a committed golden; the document defines the ownership and update-pol
   Read the complete file with read blocks=["https://m.sheaf.less.rest/3CV92Z/source-files/cGxhbm5pbmcvdHJhY2tzL2N1cnJlbnQtZW5naW5lLXJlZmFjdG9yaW5nL2l0ZW1zL0VORy0wMDItY2hhcmFjdGVyaXplLXJlZmFjdG9yaW5nLXNlYW1zLm1k#content"]

8. Source file: planning/tracks/current-engine-refactoring/items/ENG-012-tighten-presentation-bridge.md
   Resource: https://m.sheaf.less.rest/3CV92Z/source-files/cGxhbm5pbmcvdHJhY2tzL2N1cnJlbnQtZW5naW5lLXJlZmFjdG9yaW5nL2l0ZW1zL0VORy0wMTItdGlnaHRlbi1wcmVzZW50YXRpb24tYnJpZGdlLm1k#content
   Size: 1791 bytes, 46 lines
   Matching excerpt:
      +++ id = "ENG-012" title = "Keep quantity-to-texture conversion inside presentation bridges" rfc = "RFC-0001" track = "current-engine-refactoring" status = "done" depends_on = ["ENG-011"] order = 50 areas = ["game", "render", "map"] +++ # Keep quantity-to-texture conversion inside presentation bridges ## Outcome `SurfacePresentation` and `WaterPresentation` are the sole conversion points from intrinsic quantities to renderer texture lanes and normalized scalars. ## Scope Audit existing uploads and migrate them to the bridge. Keep renderer contracts concrete; this is not a general serialization layer. ## Acceptance - Gameplay and terrain rules retain typed quantities. - GPU-facing floats are produced only at a named presentation boundary. - Existing terrain and water captures remain equivalent. ## Evidence `SurfacePresentation` owns every terrain-material texture upload. Its narrow path route converts a rebuilt `TrailNetwork` at the same boundary, while a pristine Terrain Lab reuses the already materialized path payload; Terrain Lab no longer calls `Renderer::set_terrain_paths` itself. `WaterPresentation` now receives a metre-valued datum and typed world extent, constructs the numer
   Read the complete file with read blocks=["https://m.sheaf.less.rest/3CV92Z/source-files/cGxhbm5pbmcvdHJhY2tzL2N1cnJlbnQtZW5naW5lLXJlZmFjdG9yaW5nL2l0ZW1zL0VORy0wMTItdGlnaHRlbi1wcmVzZW50YXRpb24tYnJpZGdlLm1k#content"]

9. Source file: plan/done/rfc-007-waterline-conforming-geometry.md
   Resource: https://m.sheaf.less.rest/3CV92Z/source-files/cGxhbi9kb25lL3JmYy0wMDctd2F0ZXJsaW5lLWNvbmZvcm1pbmctZ2VvbWV0cnkubWQ#content
   Size: 4302 bytes, 87 lines
   Matching excerpt:
      # RFC-007: Waterline-conforming geometry - Status: Draft - Area: rendering (water + terrain) - Interacts with: RFC-006 (channel banks), RFC-008 (tessellation snap); promotes item 4 of `ideas/geometry-from-fields.md` ## Problem The shoreline is where the lattice shows most. Water renders on grids whose fragments discard where dry, so the wet/dry boundary is resolved per fragment against bilinear sheets: the visible edge is a sawtooth at lattice scale, softened by swash and foam shading but never actually straightened. Terrain has no crease at the waterline at all. Every shore -- sea, lake, and river bank -- advertises the grid. ## Current situation - The coarse ocean grid and the Metal3 near-field mesh pipeline both discard dry fragments; the mesh path probes 15x15-cell tiles for wetness exactly (water-minus-ground is bilinear per cell, so corner probes cannot miss -- `docs/renderer-design.md`), but emitted lattices still end at cell boundaries. - The water surface sheet is `ground` in dry cells and stamped levels in wet ones (`paint_watercourses`), so `w - z` is a well-defined bilinear function per cell whose zero set *is* the shoreline. - Standing water is static per world (Lab ed
   Read the complete file with read blocks=["https://m.sheaf.less.rest/3CV92Z/source-files/cGxhbi9kb25lL3JmYy0wMDctd2F0ZXJsaW5lLWNvbmZvcm1pbmctZ2VvbWV0cnkubWQ#content"]

10. Source file: moppe/terrain/waterline.hh
   Resource: https://m.sheaf.less.rest/3CV92Z/source-files/bW9wcGUvdGVycmFpbi93YXRlcmxpbmUuaGg#content
   Size: 3368 bytes, 77 lines
   Matching excerpt:
      #ifndef MOPPE_TERRAIN_WATERLINE_HH #define MOPPE_TERRAIN_WATERLINE_HH #include <moppe/spatial/bundle.hh> #include <moppe/terrain/domain.hh> #include <moppe/terrain/flood.hh> #include <vector> namespace moppe::terrain { // The waterline as geometry: ordered polylines along the zero set of // water-minus-ground, extracted once per world by marching squares // over the terrain lattice. Within a cell the zero set of the // bilinear difference is a hyperbola branch; one or two straight // segments per boundary cell approximate it to well under a // centimetre at metre-scale cells. This is the one true wet/dry // curve that the water discard, the tile probe, and the terrain wet // band each rediscover per fragment -- extracted as a reusable // reading for conforming geometry, shore ribbons, audio, and // gameplay. Deterministic: cells scan in index order and chains // start from the smallest lattice edge. struct WaterlineContour { // The wet body this stretch of shoreline belongs to. WaterBodyId body = no_water_body; // Closed loops (island coasts, lake shores) repeat no point; the last // segment implicitly returns to the front. Open contours are retained // defensively, although a comp
   Read the complete file with read blocks=["https://m.sheaf.less.rest/3CV92Z/source-files/bW9wcGUvdGVycmFpbi93YXRlcmxpbmUuaGg#content"]

Approximate matches

1. Source: Large Scale Terrain Generation from Tectonic Uplift and Fluvial Erosion (#96ZMGK), Adrien Peytavie, Bedrich Benes, Guillaume Cordonnier, Jean Braun, Marie-Paule Cani, Éric Galin, Éric Guérin, p. 8
  Context:
    #A48PSA Large Scale Terrain Generation from Tectonic Uplift and Fluvial Erosion
      #A8NK92 6. Results
        #AWRWEN 6.4. Stream power erosion
  Score: 0.022
  Related excerpt #R2E2MJ:
      Furthermore, we can obtain interesting features by procedurally adjusting the thermal slope. Figure 18 shows a landscape with small thermal slopes below a given height, but higher slopes above it. This adds cliffs to the crests, which is typical for many mountains.

2. Source: Terrain Generation Using Procedural Models Based on Hydrology (#DMTA8Y), Adrien Peytavie, Bedřich Beneš, Jean-David Génevaux, Éric Galin, Éric Guérin, p. 5
  Context:
    #RULAFW Terrain Generation Using Procedural Models Based on Hydrology
      #T6FSBF 5 River Classification
        #TRR58W 5.1 Segmentation and Elevation of Crests
  Score: 0.021
  Related excerpt #NNUDBB:
      or given by the user. It describes which parts of the terrain will become plains, plateaus, valleys, or mountains. Further, this function can be weighted according to the distance to the coast and to the elevation of the nodes to generate either smoother valleys or sharp features as in cliffs.

3. Source: Physically-based analytical erosion for fast terrain generation (#DWXKYQ), Boris Gailleton, Guillaume Cordonnier, Petros Tzathas, Philippe Steer, p. 11
  Context:
    #JDHNVB Physically-based analytical erosion for fast terrain generation
      #PZFF56 7. Results
        #V6AZDH 7.3. Applicability of our method
  Score: 0.023
  Related excerpt #CLYRVZ:
      Escarpments are steep slopes that separate flat areas of different elevations. The sudden change in elevation yields a strong erosive response, that illustrates the need for the advective component of the analytical solutions. Indeed, a simpler solution that would only model a progressive reduction of the slopes would only cause a local smoothing of the cliffs, while the stream power law predicts a retreat of the cliff along the drainage pattern at a speed that depends on the river discharge [SS20]. We illustrate this behavior in

4. Source: Physically-based analytical erosion for fast terrain generation (#DWXKYQ), Boris Gailleton, Guillaume Cordonnier, Petros Tzathas, Philippe Steer, p. 11
  Context:
    #JDHNVB Physically-based analytical erosion for fast terrain generation
      #PZFF56 7. Results
        #V6AZDH 7.3. Applicability of our method
  Score: 0.022
  Related excerpt #7G84VM:
      Figure 12, where we start from a procedurally generated cliff that separates two areas with uniform elevation (left). Then we apply our method without uplift and observe the cliff retreating after 200 and 500\text{ky} . Note that without uplift, without deposition, and with flat boundary conditions, the retreating cliff leaves open a flat area around the main rivers.

5. Source: Principles of Trail Layout and Design (#LXV9AT), California State Parks, p. 59
  Context:
    #HE95FY Chapter 5. Principles of Trail Layout and Design
      #EEPQMJ 5.7. Trail Layout
        #8BZAPC 5.7.7. Flagging the Trail Alignment
          #AGRR47 5.7.7.1. Initial Flagging Process
            #SKHQPC SIGHTING FOR GRADE WITH CLINOMETER
  Score: 0.028
  Related excerpt #CBKMJC:
      Photo 5.40 illustrates how, following traditional construction practices, a trail constructed on a 30% hillslope would be half native bench and half fill bench (yellow line). However, by constructing further into the hillslope the entire trail bed is comprised of native material (red line).

6. Source: Principles of Trail Layout and Design (#LXV9AT), California State Parks, p. 61
  Context:
    #HE95FY Chapter 5. Principles of Trail Layout and Design
      #EEPQMJ 5.7. Trail Layout
        #8BZAPC 5.7.7. Flagging the Trail Alignment
          #AGRR47 5.7.7.1. Initial Flagging Process
            #SKHQPC SIGHTING FOR GRADE WITH CLINOMETER
  Score: 0.026
  Related excerpt #82N8XD:
      NOTE: AMOUNT OF TRAIL BENCH VARIES LINEARLY W/ % OF SIDE SLOPE. ALL SOIL SHOULD BE MINERAL AND CONTAIN NO ORGANIC MATERIAL.

7. Source: Principles of Trail Layout and Design (#LXV9AT), California State Parks, p. 15
  Context:
    #HE95FY Chapter 5. Principles of Trail Layout and Design
      #BUKYGV 5.5. Mechanical Wear
        #SUVWGE 5.5.5. Parent Soil Strength and Durability
  Score: 0.023
  Related excerpt #4GDZAB:
      The composition of the soil comprising the trail tread also affects the rate of mechanical wear. Native tread material can vary from sand to bedrock. The harder and more consolidated the tread surface, the more resistant it is to mechanical wear. (See Photo 5.12.)

8. Source: Interactive procedural street modeling (#V4TQYB), Eugene Zhang, Gregory Esch, Guoning Chen, Pascal Müller, Peter Wonka, p. 3
  Context:
    #57PDWB Interactive Procedural Street Modeling
      #QNKCB5 5 Tensor Field Generation
        #FCEMBJ 5.1 Generation of Basis Fields
  Score: 0.023
  Related excerpt #UB8S5G:
      Boundary Field: There are many examples of roads that are built at the boundaries of natural or man-made structures. Examples are roads next to the shoreline, such as California Highway One (see Figure 6). Other examples are roads at the boundaries of parks and roads surrounding population centers.

9. Source file: moppe/map/surface.cc
   Resource: https://m.sheaf.less.rest/3CV92Z/source-files/bW9wcGUvbWFwL3N1cmZhY2UuY2M#content
   Size: 24623 bytes, 537 lines
  Score: 0.035
   Related excerpt:
      forest or clearing; the band is narrow // so the edges between them stay edges instead of a long gradient. const auto seeded = band (gate - 0.085f * signal, gate + 0.085f * signal, mosaic); // A route keeps almost all canopy off itself; a settlement clears its // ground completely. const auto trodden = use[site]; const auto route_clearance = 1 - 0.96f * get<trail_influence> (trodden); const auto settled_clearance = 1 - get<home_base_influence> (trodden); // Every factor is a soft yes between 0 and 1, and multiplying them is // a soft "and": canopy needs habitable ground AND a seeded patch AND no // route AND no settlement. Any one of them near zero vetoes the rest, // which is why a place can fail four mild tests and still come out // bare. Adding them would say "any of these will do", which is not how // a forest works. // Habitat has already chosen where the stands are; here it only says // how thickly they grow, which is what placement reads for density, // height, and tint. const auto thickness = 0.45f + 0.55f * habitable; const auto wanted = thickness * seeded * route_clearance * settled_clearance; // The bands are in range by construction, but the trail and home-base // readi
   Read the complete file with read blocks=["https://m.sheaf.less.rest/3CV92Z/source-files/bW9wcGUvbWFwL3N1cmZhY2UuY2M#content"]

10. Source file: moppe/shaders/metal/terrain.metal
   Resource: https://m.sheaf.less.rest/3CV92Z/source-files/bW9wcGUvc2hhZGVycy9tZXRhbC90ZXJyYWluLm1ldGFs#content
   Size: 46211 bytes, 977 lines
  Score: 0.029
   Related excerpt:
      est [[texture (MOPPE_TEX_TERRAIN_FOREST)]], texture2d<float> terrain_snow_support [[texture (MOPPE_TEX_TERRAIN_SNOW_SUPPORT)]], texture2d<float> terrain_channel_flux [[texture (MOPPE_TEX_TERRAIN_CHANNEL_FLUX)]], sampler smp [[sampler (0)]]) { const float3 to_frag = in.world_pos - u.camera_pos.xyz; const float dist = length (to_frag); const float3 view_dir = to_frag / max (dist, 1e-4); const float3 l = u.sun_dir.xyz; const float3 fog_c = moppe_warmed_fog (u.fog_color.rgb, view_dir, l); // Fully fogged: skip all texture and shadow work. const float fog_factor = smoothstep (0.0, 0.9, in.fog); if (fog_factor >= 0.995) return float4 (fog_c, 1.0); // Native and coarser LODs light from the full-resolution normal // texture at fragment rate: a stride-8 silhouette carries full // shading detail, exactly as a normal-mapped mesh does. The // subdivided near field keeps its analytic surface normals. float3 n = (u.params6.x > 0.5 && in.lod_step >= 1.0) ? normalize (terrain_normal_filtered (in.grid_coord, normals)) : normalize (in.normal); const float height = in.height; const float sea_level = u.params1.y; // Hydrology is material information. // Standing water makes its bed fully wet; the mois
   Read the complete file with read blocks=["https://m.sheaf.less.rest/3CV92Z/source-files/bW9wcGUvc2hhZGVycy9tZXRhbC90ZXJyYWluLm1ldGFs#content"]

### 5. Assistant tool calls

#### Tool call: `web_search`

```json
{
  "query": "Peytavie Galin \"Arches\" framework modeling complex terrains rocks sand layered materials Eurographics 2009 citation"
}
```

#### Tool call: `web_search`

```json
{
  "query": "best textbook coastal geomorphology swash zone beach profile sediment sorting Masselink Hughes introduction to coastal processes"
}
```

#### Tool call: `web_search`

```json
{
  "query": "Hjulström curve sediment grain size erosion transport deposition threshold explanation"
}
```

### 6. Tool result: web_search

WEB SEARCH RESULTS
Query: Peytavie Galin "Arches" framework modeling complex terrains rocks sand layered materials Eurographics 2009 citation

### Full citation

Peytavie, A., Galin, É., Grosjean, J., & Mérillou, S. (2009). Arches: A framework for modeling complex terrains. *Computer Graphics Forum, 28*(2), 457–467. doi: **10.1111/j.1467-8659.2009.01385.x**.  
Published in the proceedings of **Eurographics 2009**. ([diglib.eg.org](https://diglib.eg.org/items/fe20de3e-be7c-49c9-b003-f1afcf282db5?utm_source=openai))

### BibTeX

```bibtex
@article{Peytavie2009Arches,
  author  = {Adrien Peytavie and Eric Galin and
             J{\'e}r{\^o}me Grosjean and St{\'e}phane M{\'e}rillou},
  title   = {Arches: A Framework for Modeling Complex Terrains},
  journal = {Computer Graphics Forum},
  volume  = {28},
  number  = {2},
  pages   = {457--467},
  year    = {2009},
  doi     = {10.1111/j.1467-8659.2009.01385.x}
}
```

**In-text citation:** `(Peytavie et al., 2009)` or `Peytavie et al. [2009]`.

Cited sources:
- Arches: a Framework for Modeling Complex Terrains: https://diglib.eg.org/items/fe20de3e-be7c-49c9-b003-f1afcf282db5?utm_source=openai

### 7. Tool result: web_search

WEB SEARCH RESULTS
Query: best textbook coastal geomorphology swash zone beach profile sediment sorting Masselink Hughes introduction to coastal processes

## Best match for your topics

**Gerd Masselink, Michael G. Hughes & Jasper Knight — *Introduction to Coastal Processes and Geomorphology*, 2nd ed.**  
**ISBN:** 978-1-4441-2240-4

This is probably the **best single textbook** if your priorities are:

- swash-zone processes  
- beach profiles and beach morphodynamics  
- grain-size effects and sediment sorting  
- surf-zone waves and currents  
- cross-shore and longshore sediment transport  
- shoreface–beach–barrier systems  

Relevant sections include **wave processes in the surf and swash zones**, **sediment properties and transport**, and an entire chapter on **wave-dominated shorefaces, beaches, and barriers**. Its systems-and-morphodynamics approach connects hydrodynamics, sediment characteristics, and beach form particularly well. ([routledge.com](https://www.routledge.com/Introduction-to-Coastal-Processes-and-Geomorphology/Masselink-Hughes-Knight/p/book/9781444122404?utm_source=openai))

### Useful alternatives

1. **Davidson-Arnott, Bauer & Houser — *Introduction to Coastal Processes and Geomorphology*, 2nd ed. (2019)**  
   More recent and comprehensive. Particularly strong chapters on coastal sediment transport, cross-shore transport, beach and nearshore sediments, and beach morphodynamics. Choose this for a broader, updated university-level treatment. Note that it has the **same title** as the Masselink book but different authors and publisher. ([cambridge.org](https://www.cambridge.org/highereducation/books/introduction-to-coastal-processes-and-geomorphology/E1F336231A754F0DD06BD4174B2530E7))

2. **Dean & Dalrymple — *Coastal Processes with Engineering Applications***  
   Best if you want a more mathematical or engineering-oriented treatment. It has dedicated sections on swash-zone dynamics, beach-profile measurement and analysis, equilibrium beach profiles, and sediment transport. ([assets.cambridge.org](https://assets.cambridge.org/97805214/95356/frontmatter/9780521495356_frontmatter.pdf?utm_source=openai))

### Bottom line

- **Best for your exact list of subjects:** **Masselink, Hughes & Knight**
- **Best broader and more recent coastal-geomorphology text:** **Davidson-Arnott, Bauer & Houser**
- **Best for quantitative beach-profile modeling:** **Dean & Dalrymple**

If buying only one specifically for **swash, beach profiles, and sediment sorting**, get **Masselink et al., 2nd edition**.

Cited sources:
- Introduction to Coastal Processes and Geomorphology - 2nd Edition - Ge: https://www.routledge.com/Introduction-to-Coastal-Processes-and-Geomorphology/Masselink-Hughes-Knight/p/book/9781444122404?utm_source=openai
- Introduction to Coastal Processes and Geomorphology | Cambridge Aspire website: https://www.cambridge.org/highereducation/books/introduction-to-coastal-processes-and-geomorphology/E1F336231A754F0DD06BD4174B2530E7
- Cambridge University Press & Assessment: https://assets.cambridge.org/97805214/95356/frontmatter/9780521495356_frontmatter.pdf?utm_source=openai

### 8. Tool result: web_search

WEB SEARCH RESULTS
Query: Hjulström curve sediment grain size erosion transport deposition threshold explanation

## Hjulström curve explained

The **Hjulström curve** shows how **water velocity** affects the **erosion, transport, and deposition** of sediment grains of different sizes.

### Axes

- **Horizontal axis:** sediment grain diameter, usually in **millimetres**, on a logarithmic scale  
  - Clay → silt → sand → gravel → cobbles
- **Vertical axis:** water-flow velocity, usually in **cm/s** or **m/s**, also often logarithmic

### Three zones

1. **Erosion**
   - Flow velocity is high enough to lift grains from the bed.
   - Above the **erosion threshold curve**, sediment becomes entrained.

2. **Transport**
   - Grains are already moving by suspension, saltation, or rolling.
   - This region lies mainly between the erosion and deposition thresholds.
   - A velocity too weak to erode a grain may still be strong enough to transport it once it is moving.

3. **Deposition**
   - Flow velocity is too low to keep grains moving.
   - Below the **deposition threshold**, sediment settles onto the bed.

## How grain size affects the thresholds

### Clay and fine silt

Clay particles are extremely small, but they are **difficult to erode** because they are cohesive: electrochemical forces bind the particles together.

Once eroded, however, clay settles very slowly and can remain suspended even in weak currents.

> **High velocity needed for erosion, but very low velocity needed for deposition.**

### Fine to medium sand

Fine and medium sand is generally the **easiest material to erode** because:

- It has little cohesion.
- Individual grains are not very heavy.

The lowest erosion threshold is approximately around **fine-to-medium sand**, although exact values vary with bed conditions.

### Coarse sand, gravel, and cobbles

As grain size increases, particles become heavier. Increasingly high flow velocities are therefore required to lift or roll them.

These coarse particles also settle rapidly when velocity decreases.

> **Larger grains require stronger currents for erosion and transport.**

## Why the erosion curve is U-shaped

The erosion threshold is high at both ends:

- **Fine sediment:** difficult to erode because of cohesion.
- **Coarse sediment:** difficult to erode because of grain weight.
- **Sand-sized sediment:** easiest to erode because it has relatively little cohesion and moderate weight.

## Example

Suppose a river slows as it enters a lake:

1. Gravel is deposited first.
2. Sand is deposited next.
3. Silt settles farther from the river mouth.
4. Clay may travel far into the lake before eventually settling.

This produces **sediment sorting** by grain size.

### Key idea

**Erosion depends on whether flow can start grain movement, whereas deposition depends mainly on whether flow can continue supporting or moving the grain.**

The Hjulström curve is a conceptual empirical model. Actual thresholds also depend on grain shape, packing, bed roughness, water depth, turbulence, and sediment cohesion.

Cited sources:
(no cited sources)

### 9. Assistant tool calls

#### Tool call: `write_note`

```json
{
  "block_ids": [
    "KSESR8",
    "WYP3G6",
    "W5DSFW",
    "7YZU95",
    "XZX6PE",
    "AK7NGE",
    "C4AY2M",
    "8SERGP",
    "5KNTTV"
  ],
  "text": "Reading plan for terrain material boundaries (boulders, gravel, splash/swash, beach):\n\n1. Geomorphology (why zones exist): Hjulström–Sundborg curve — flow energy vs grain size gives erosion/transport/deposition thresholds; material boundaries = energy gradients, implementable from flux/slope fields. Masselink, Hughes & Knight, *Introduction to Coastal Processes and Geomorphology* (2nd ed., ISBN 978-1-4441-2240-4) for swash zone, beach profiles, sediment sorting. Wentworth grain-size scale + angle of repose for talus/boulder fields.\n\n2. Ontology (kind of boundary): Smith #KSESR8 fiat vs bona fide; #WYP3G6 esp. #W5DSFW on continuous (lake→marsh→wetland) vs gapped concept transitions — gradient vs crisp boundaries should be represented differently; #7YZU95 mereotopology; #XZX6PE vague reference.\n\n3. Graphics: Peytavie, Galin, Grosjean, Mérillou, \"Arches: A Framework for Modeling Complex Terrains\", CGF 28(2) 2009, doi:10.1111/j.1467-8659.2009.01385.x — layered material stacks (bedrock/rocks/sand/water) with angle-of-repose stabilization; NOT yet in corpus, candidate import. Desertscape Simulation (Paris et al. ~2019) for aeolian sand. In corpus: #AK7NGE riverscapes, #C4AY2M foam/spray, #8SERGP breaking waves, #5KNTTV transition-between-representations pattern.\n\nUnifying idea: a terrain boundary is where a process changes regime (transport threshold, repose angle, wetting frequency). Connects to moppe's waterline-as-zero-set (RFC-007) — the wet/dry contour is a regime boundary.",
  "title": "Reading plan: terrain material boundaries"
}
```

### 10. Tool result: write_note

NOTE SAVED #C8BGUG
IRI: https://m.sheaf.less.rest/C8BGUG

### 11. Assistant

Saved as note #C8BGUG. Concrete next step: get the Arches paper (2009, CGF) into the corpus — it's the single closest match to the boulders/gravel question, and everything else on the list radiates from it.

### 12. User

ah cool i imported the arches paper now

### 13. Assistant tool calls

#### Tool call: `search_text`

```json
{
  "limit": 5,
  "query": "Arches framework modeling complex terrains"
}
```

### 14. Tool result: search_text

Exact matches

1. Source: Reading plan: terrain material boundaries (#C8BGUG)
  Matching note #C8BGUG:
      Reading plan for terrain material boundaries (boulders, gravel, splash/swash, beach): 1. Geomorphology (why zones exist): Hjulström–Sundborg curve — flow energy vs grain size gives erosion/transport/deposition thresholds; material boundaries = energy gradients, implementable from flux/slope fields. Masselink, Hughes & Knight, *Introduction to Coastal Processes and Geomorphology* (2nd ed., ISBN 978-1-4441-2240-4) for swash zone, beach profiles, sediment sorting. Wentworth grain-size scale + angle of repose for talus/boulder fields. 2. Ontology (kind of boundary): Smith #KSESR8 fiat vs bona fide; #WYP3G6 esp. #W5DSFW on continuous (lake→marsh→wetland) vs gapped concept transitions — gradient vs crisp boundaries should be represented differently; #7YZU95 mereotopology; #XZX6PE vague reference. 3. Graphics: Peytavie, Galin, Grosjean, Mérillou, "Arches: A Framework for Modeling Complex Terrains", CGF 28(2) 2009, doi:10.1111/j.1467-8659.2009.01385.x — layered material stacks (bedrock/rocks/sand/water) with angle-of-repose stabilization; NOT yet in corpus, candidate import. Desertscape Simulation (Paris et al. ~2019) for aeolian sand. In corpus: #AK7NGE riverscapes, #C4AY2M foam/spray, #8SERGP breaking waves, #5KNTTV transition-between-representations pattern. Unifying idea: a terrain boundary is where a process changes regime (transport threshold, repose angle, wetting frequency). Connects to moppe's waterline-as-zero-set (RFC-007) — the wet/dry contour is a regime boundary.

2. Source: Arches: A Framework for Modeling Complex Terrains (#Y55KCV), A. Peytavie, E. Galin, J. Grosjean, S. Mérillou, p. 9
  Context:
    #9AB4SJ Arches: a Framework for Modeling Complex Terrains
      #5JW9F9 8. Conclusion
  Matching excerpt #BELMDM:
      We have presented an original approach for representing complex terrains. Our framework can model overhangs, arches, or caves with granular materials such as sand and rocks. Our hybrid model combines a compact material layer data structure and an implicit representation for sculpting and reconstructing the surface of the terrain. We have proposed several high level tools for authoring complex scenes.

3. Source: Arches: A Framework for Modeling Complex Terrains (#Y55KCV), A. Peytavie, E. Galin, J. Grosjean, S. Mérillou, p. 0
  Context:
    #9AB4SJ Arches: a Framework for Modeling Complex Terrains
      #U6R3DX Abstract
  Matching excerpt #BU5SKV:
      In this paper, we present a framework for representing complex terrains with such features as overhangs, arches and caves and including different materials such as sand and rocks. Our hybrid model combines a volumetric discrete data structure that stores the different materials and an implicit representation for sculpting and reconstructing the surface of the terrain. Complex scenes can be edited and sculpted interactively with high level tools. We also propose an original rock generation technique that enables us to automatically generate complex rocky sceneries with piles of rocks without any computationally demanding physically-based simulation.

4. Source: Arches: A Framework for Modeling Complex Terrains (#Y55KCV), A. Peytavie, E. Galin, J. Grosjean, S. Mérillou, p. 0
  Context:
    #9AB4SJ Arches: a Framework for Modeling Complex Terrains
      #RA5CYD 1. Introduction
  Matching excerpt #QAV44L:
      ing complex terrains with overhangs, arches and caves. Our goal is to propose a compact and efficient model that lends itself for real time editing. Therefore, our goal is not to focus on a physically based modeling system. Instead, we aim at generating physically plausible scenes in real time with physically inspired and phenomenological techniques. More precisely, the main contributions of this paper are as follows:

5. Source: Arches: A Framework for Modeling Complex Terrains (#Y55KCV), A. Peytavie, E. Galin, J. Grosjean, S. Mérillou, p. 8
  Context:
    #9AB4SJ Arches: a Framework for Modeling Complex Terrains
      #RKFLXM 7. Results
  Matching excerpt #YYZ987:
      We have implemented our hybrid terrain model and the modeling tools into a modeling application coded in C++. We have applied our method to create different varieties of complex rocky sceneries with complex geological features including caves (Figure 20), cliffs with overhangs (Figure 22) and arches (Figure 23).

Approximate matches

1. Source: Arches: A Framework for Modeling Complex Terrains (#Y55KCV), A. Peytavie, E. Galin, J. Grosjean, S. Mérillou, p. 9
  Context:
    #9AB4SJ Arches: a Framework for Modeling Complex Terrains
      #5JW9F9 8. Conclusion
  Score: 0.025
  Related excerpt #BELMDM:
      We have presented an original approach for representing complex terrains. Our framework can model overhangs, arches, or caves with granular materials such as sand and rocks. Our hybrid model combines a compact material layer data structure and an implicit representation for sculpting and reconstructing the surface of the terrain. We have proposed several high level tools for authoring complex scenes.

2. Source: Arches: A Framework for Modeling Complex Terrains (#Y55KCV), A. Peytavie, E. Galin, J. Grosjean, S. Mérillou, p. 0
  Context:
    #9AB4SJ Arches: a Framework for Modeling Complex Terrains
      #U6R3DX Abstract
  Score: 0.023
  Related excerpt #BU5SKV:
      In this paper, we present a framework for representing complex terrains with such features as overhangs, arches and caves and including different materials such as sand and rocks. Our hybrid model combines a volumetric discrete data structure that stores the different materials and an implicit representation for sculpting and reconstructing the surface of the terrain. Complex scenes can be edited and sculpted interactively with high level tools. We also propose an original rock generation technique that enables us to automatically generate complex rocky sceneries with piles of rocks without any computationally demanding physically-based simulation.

3. Source: Arches: A Framework for Modeling Complex Terrains (#Y55KCV), A. Peytavie, E. Galin, J. Grosjean, S. Mérillou, p. 0
  Context:
    #9AB4SJ Arches: a Framework for Modeling Complex Terrains
      #RA5CYD 1. Introduction
  Score: 0.022
  Related excerpt #QAV44L:
      ing complex terrains with overhangs, arches and caves. Our goal is to propose a compact and efficient model that lends itself for real time editing. Therefore, our goal is not to focus on a physically based modeling system. Instead, we aim at generating physically plausible scenes in real time with physically inspired and phenomenological techniques. More precisely, the main contributions of this paper are as follows:

4. Source: Arches: A Framework for Modeling Complex Terrains (#Y55KCV), A. Peytavie, E. Galin, J. Grosjean, S. Mérillou, p. 1
  Context:
    #9AB4SJ Arches: a Framework for Modeling Complex Terrains
      #RA5CYD 1. Introduction
  Score: 0.02
  Related excerpt #SVQWPR:
      Terrain authoring tools We propose a framework that combines some high level terrain modeling and sculpting tools with a simplified physically inspired simulation kernel which automatically stabilizes layers of sand and rocks according to their repose angle. This architecture enables the designer to create complex scenes without the burden of finely editing details by hand.

5. Source: Arches: A Framework for Modeling Complex Terrains (#Y55KCV), A. Peytavie, E. Galin, J. Grosjean, S. Mérillou, p. 0
  Context:
    #9AB4SJ Arches: a Framework for Modeling Complex Terrains
  Score: 0.013
  Related excerpt #MWU99R:
      A. Peytavie 1 , E. Galin 2 , J. Grosjean 3 , S. Merillou 4 .

### 15. Assistant tool calls

#### Tool call: `get_document`

```json
{
  "id": "Y55KCV"
}
```

### 16. Tool result: get_document

DOCUMENT #Y55KCV
Title: Arches: A Framework for Modeling Complex Terrains

Outline:
  - 1 #9AB4SJ Arches: a Framework for Modeling Complex Terrains
    - 1.1 #U6R3DX Abstract
    - 1.2 #RA5CYD 1. Introduction
    - 1.3 #V5AWA5 2. Related work
    - 1.4 #C9XCC4 3. Modeling
      - 1.4.1 #N8TSTD 3.1. Architecture
      - 1.4.2 #X87JKF 3.2. Material layers
      - 1.4.3 #87NJTQ 3.3. Implicit representation
      - 1.4.4 #ZNNYUC 3.4. Stabilization simulation
    - 1.5 #T7UNZF 4. Editing process
      - 1.5.1 #84V9Z6 4.1. Bedrock sculpting
      - 1.5.2 #NYPHUG 4.2. Modeling cracks, fractures and tunnels by sweeping
      - 1.5.3 #H66BPQ 4.3. Adding granular material
      - 1.5.4 #DQQKSJ 4.4. Erosion
    - 1.6 #34UQCF 5. Modeling rock piles
    - 1.7 #BXJYQV 6. Rendering
    - 1.8 #RKFLXM 7. Results
    - 1.9 #5JW9F9 8. Conclusion
    - 1.10 #NY59JZ Acknowledgements
    - 1.11 #48RMMM References

### 17. Assistant tool calls

#### Tool call: `read`

```json
{
  "blocks": [
    "X87JKF",
    "ZNNYUC",
    "34UQCF"
  ],
  "expand": true
}
```

### 18. Tool result: read

DOCUMENT #Y55KCV
Arches: A Framework for Modeling Complex Terrains

SECTION #X87JKF 3.2. Material layers

EXCERPT #LK24UT p. 2
  A terrain is defined as a two dimensional grid of material stacks (Figure 3). A material stack is defined as a stack of material layers that are characterized by their thickness and the corresponding material type [BF01]. Our framework currently handles air, water, sand, bedrock, and rocks. Overhangs, arches and caves can be easily created by inserting an air layer between two bedrock layers (Figure 3).

EXCERPT #RD3GSF p. 2
  This data-structure is both computationally efficient and less memory demanding than a voxel decomposition of space [JFMC03, BFO*07]. It can store and process complex terrains with many different and complex geological features such as caves (Figure 20), cliffs (Figure 22) and arches (Figure 23) with an effective resolution exceeding 1000 \times 750 \times 8000 (6 billion voxels) with less than 21 megabytes. More statistics can be found in Section 7.

EXCERPT #FRGD5A p. 2
  Figure 3: Overview of material layer and material stack data-structures. The diagram shows a legend for material types: Air (white), Water (blue), Rocks (grey), Sand (yellow), and Bedrock (brown). It then shows a 'Material Stack' as a vertical column of these materials. To the right, an 'Array of Material Stacks' shows a grid of such stacks, with some stacks having different heights and compositions, illustrating overhangs and caves.

EXCERPT #ALTZPH p. 2
  Figure 3: Overview of material layer and material stack data-structures.

EXCERPT #Q7Z7NT p. 2
  For every material \mathcal{M} , we define a point membership classification function, denoted as g_{\mathcal{M}}(\mathbf{p}) , which returns 1 if the material at point \mathbf{p} is \mathcal{M} and 0 otherwise. Those functions will be used to define the potential function of the implicit representation.

DOCUMENT #Y55KCV
Arches: A Framework for Modeling Complex Terrains

SECTION #ZNNYUC 3.4. Stabilization simulation

EXCERPT #C55XGR p. 3
  The bedrock layer is always considered as stable, whereas other materials such as sand and rocks should stabilize into successive layers over the bedrock.

EXCERPT #57GG95 p. 3
  Simulating the complex behavior of different granular and continuous materials interacting and blending together is extremely difficult. The angle of repose between two materials is defined as the angle between the horizontal plane and the plane of contact between the two materials when the upper layer is about to slide over the lower. The characterization of the angle of repose of binary granular materials remains a challenging problem. Therefore, we process the different material layer separately.

EXCERPT #2QQXVF p. 3
  Figure 6: Layer merging and sorting process. The left diagram shows 'Merging' of layers and 'Ordering' of layers. The right diagram shows 'Inconsistent layers' being transformed into 'Consistently ordered layers'.

EXCERPT #THF6R7 p. 3
  Figure 6: Layer merging and sorting process.

EXCERPT #AX5Q22 p. 3
  For all material layers located between two stable bedrock layers, we first merge all the material layers of the same kind (Figure 6). While this prevents us from modeling successive strata of granular materials such as a rock layer between two sediment layers, it greatly simplifies our stabilization algorithm. Then, we sort the material layers above one bedrock layer in the following order: sand, rocks and air. Sorting enables us to use a single angle of repose for every material.

EXCERPT #LQKVMU p. 3
  Figure 7: Stabilization of the material layers according to the angle of repose. The left diagram shows 'Unstabilized layers' with a 'Fall' arrow indicating a layer sliding down. The right diagram shows 'Stabilized layers' with 'Sand slope' and 'Rock slope' labels indicating the angle of repose for different materials.

EXCERPT #JGQ2LT p. 3
  Figure 7: Stabilization of the material layers according to the angle of repose of the different materials.

EXCERPT #C375DM p. 3
  Eventually, we perform a stabilization simulation step for every material, starting from bottom layers to top layers (Figure 7). Our stabilization simulation is based on the displacement of material from one stack to its neighbors according to the repose angle \alpha of every material [MKM89, BF01]. In our implementation, we use 30 – 35 degrees for sand and 40 – 45 degrees for rocks.

EXCERPT #TADYEX p. 3

EXCERPT #CFCZ8J p. 4

EXCERPT #BBNRUW p. 4
  Let h denote the height of a given rock or sand material stack and h_i , i \in [1, 8] the height of its eight neighbors. We denote the height difference between the central stack and its neighbors by \Delta h_i = h_i - h .

EXCERPT #4YVKDP p. 4
  Figure 8: Diagrams illustrating notations for the stabilization algorithm. The left diagram shows a central stack of height h and its neighbors at heights h_{i-1} and h_{i+1}. The height differences are labeled Delta h_{i-1} and Delta h_{i+1}. The right diagram shows a similar setup but with a slope angle alpha indicated, and the height differences are labeled Delta h_{i-1} and Delta h_{i+1} sin alpha.

EXCERPT #YHCQJX p. 4
  Figure 8: Notations for the stabilization algorithm.

EXCERPT #LFRUYP p. 4
  Some material moves to a neighboring stack if the angle between the two stacks is greater than the angle of repose \alpha . Let s denote the size of the side of a material stack. We define \Delta \tilde{h}_i = 0 if \Delta h_i < s \tan \alpha and \Delta \tilde{h}_i = \Delta h_i - s \tan \alpha otherwise. The height of the pile of material to be moved is set as a small constant amount a so as to avoid oscillations in the algorithm. The height of material moving from the central stack to a neighboring stack \Delta z_i is defined as a weighted average proportional to the height difference:

EXCERPT #YYA985 p. 4
  \Delta z_i = a \frac{\Delta \tilde{h}_i}{\sum_{i \in [1, 8]} \Delta \tilde{h}_i}

EXCERPT #7RE7NF p. 4
  This process is repeated iteratively until all the material layers are stabilized.

DOCUMENT #Y55KCV
Arches: A Framework for Modeling Complex Terrains

SECTION #34UQCF 5. Modeling rock piles

EXCERPT #XPNS4H p. 6
  In this section, we present our method for efficiently generating a set of rocks into contact. Instead of modeling rocks separately and creating piles with physically-based collision detection techniques, we propose to directly generate rock models with contact points. Our method proceeds in three steps. First we generate a cubic tile containing Voronoi cells that can tile the entire space. Second, we create the geometry of rocks by eroding the Voronoi cells. The erosion if performed all over the surface of Voronoi cells but at some random contact points located on the faces so that rocks should nicely pack together. Finally, rock piles are created by instantiating some of the rock models in the cubic tile.

EXCERPT #QAXHWE p. 6
  Voronoi cell distribution Let \mathcal{C} denote a cubic tile. We first generate a Poisson sphere distribution [LD06] with radius r and whose centers will be denoted as \mathbf{p}_i over the cubic tile \mathcal{C} . Using a Poisson distribution of radius r enables us to control the minimum size of the created Voronoi cells, hence the size of the rocks. We consider that the cube \mathcal{C} virtually tiles space so as to be able to construct closed Voronoi cells, denoted as V_i for every center \mathbf{p}_i . The resulting set of cells periodically tiles space. Creating an aperiodic tiling of Voronoi cells over a set of Corner Cubes using a modified Poisson sphere distribution [LD06] should be possible but needs further investigations beyond the scope of this paper. In practice, we did not observe disturbing repetitive patterns in the rock piles generated with our method.

EXCERPT #NG2H5Z p. 6

EXCERPT #RCUPDV p. 7

EXCERPT #VZW6YQ p. 7
  Generating the rock geometry Rocks are created from the Voronoi cells by performing an erosion simulation step all over the surface of the cells but at some random contact points located on the faces. This method guarantees that rocks should collide and fake a stable arrangement. Recall that our goal is not to perform physically-based simulations but to generate realistic looking models. While we cannot guarantee that the piles are set in a stable configuration, our rock piles are still visually convincing.

EXCERPT #27GK99 p. 7
  Figure 17: Creation of rocks by smoothly eroding the geometry of the Voronoi cells and preserving contact points. The left diagram shows 'Generation of contact points' with a Voronoi cell structure and blue dots representing contact points. The right diagram shows 'Erosion simulation' where the cells are eroded towards these points, creating a more irregular, rock-like shape.

EXCERPT #HMDE9G p. 7
  Figure 17: Creation of rocks by smoothly eroding the geometry of the Voronoi cells and preserving contact points.

EXCERPT #GNZ92H p. 7
  Our method proceeds in two steps (Figure 17). We first create the contact points, denoted as \mathbf{c}_{ij} , by generating random points on the faces between the cells V_i and V_j . For every contact point \mathbf{c}_{ij} , we define a function denoted as \rho_{ij}(\mathbf{p}) representing the local resistance to erosion with respect to the distance \|\mathbf{p} - \mathbf{c}_{ij}\| . The resistance should be a smoothly decreasing function of the distance between a point in space and the contact point \mathbf{c}_{ij} . Recall that r is the Poisson radius, we propose to use the following Gaussian function:

EXCERPT #7BVQGB p. 7
  \rho(\mathbf{p}) = e^{-\frac{\|\mathbf{p} - \mathbf{c}_{ij}\|^2}{r^2}}

EXCERPT #6YA7TR p. 7
  For every Voronoi cell, we generate the corresponding rock geometry by simulating a uniform erosion weighted by the resistance functions (Figure 17). Our erosion simulation is based on the spheroidal erosion technique proposed in [BFO*07]. Note that this process is performed once and for all as a pre-processing step.

EXCERPT #JRPT5M p. 7
  Rock instantiation We generate rocks on the ground by analyzing every corner cube straddling a rock material layer. We instantiate rocks whose corresponding Voronoi center \mathbf{p} lies within a rock material layer (Figure 18). Although rocks on the ground may often intersect the ground mesh, those artifacts are rarely seen.

EXCERPT #RPQY4Q p. 7
  Figure 18: Rock instantiation process. The left diagram shows 'Rock tile localization' where a Voronoi cell is identified within a rock material layer. The right diagram shows 'Instantiation' where a rock instance is placed on the ground mesh, corresponding to the localized cell.

EXCERPT #6FJ8ZQ p. 7
  Figure 18: Rock instantiation process.

EXCERPT #3EJGRS p. 7
  In practice, for large rock piles, only the rocks on the top layers are visible and contribute to the final image. Therefore we eliminate rocks whose distance to the surface is larger than twice the maximum radius of Voronoi embedding spheres.

EXCERPT #D5LYKZ p. 7
  Figure 19: A closeup of rocks piled on the ground. Two side-by-side photographs showing a realistic-looking pile of rocks with varying textures and colors, rendered using the described method.

EXCERPT #CUD2SG p. 7
  Figure 19: A closeup of rocks piled on the ground.

EXCERPT #NX4C35 p. 7
  Our method creates convincing piles of rocks very efficiently by instantiating only a few different mesh models. While we cannot guarantee that the rocks are set in a stable configuration, they are into contact and the resulting arrangements look physically plausible and convincing (Figure 19).

### 19. Assistant tool calls

#### Tool call: `write_note`

```json
{
  "block_ids": [
    "Y55KCV",
    "LK24UT",
    "RD3GSF",
    "C375DM",
    "LFRUYP",
    "AX5Q22",
    "XPNS4H",
    "GNZ92H",
    "JRPT5M",
    "3EJGRS",
    "QAV44L",
    "C8BGUG"
  ],
  "text": "Skim of Arches (#Y55KCV), now imported. Key transferable mechanisms for terrain material boundaries:\n1. Material stacks: 2D grid of layered columns (bedrock/rocks/sand/water/air), thickness+type per layer (#LK24UT); very compact (#RD3GSF). Material boundaries = where a layer thins to zero.\n2. Angle-of-repose stabilization (#C375DM, #LFRUYP): move material to neighbors where slope exceeds repose angle (sand 30–35°, rocks 40–45°), amount weighted by height excess. Simplification: merge same-kind layers, sort sand<rocks<air (#AX5Q22). Gives emergent talus/beach transitions — concrete version of the \"boundary = process regime change\" idea in note #C8BGUG.\n3. Rock piles without physics (#XPNS4H): Poisson-sphere Voronoi cells in a tiling cube, eroded except at random contact points (Gaussian resistance #GNZ92H) so instanced rocks pack together; instantiate where Voronoi center falls in a rock layer (#JRPT5M), cull deep rocks (#3EJGRS).\nMoppe fit: treat gravel/sand as thin transported layers over bedrock height, sourced by flux field via Hjulström-style threshold, stabilized by repose rule as a materialization pass (not live sim — Arches is explicitly non-physical authoring, #QAV44L).",
  "title": "Arches skim: material stacks, repose stabilization, rock piles"
}
```

### 20. Tool result: write_note

NOTE SAVED #WYDTNT
IRI: https://m.sheaf.less.rest/WYDTNT

### 21. Assistant

Skim saved as note #WYDTNT. Suggested reading order within the paper: §3.2 #X87JKF and §3.4 #ZNNYUC first (the data structure and stabilization are the ideas you'd actually port), then §5 #34UQCF for the rock-pile trick; §4's sculpting tools and the implicit-surface reconstruction (§3.3) are skippable unless you want mesh-free overhangs.