Terrain Rendering

Deployed Application: https://vouillon.github.io/mountains/

A Web-based terrain rendering application capable of visualizing landscapes from Digital Elevation Models (DEMs), currently covering the French Alps. It features atmospheric rendering, triplanar detail texturing, mobile device support, and a comprehensive data pipeline for processing CORINE Land Cover (CLC) data.

Key Features

• Web Client (Primary): Written in OCaml, compiled to JavaScript/WASM via js_of_ocaml / wasm_of_ocaml, utilizing WebGL for high-performance rendering in any modern browser.
• Native Client (Legacy): Support for a desktop application using SDL2 and OpenGLES 3.0 (available for testing/debugging).
• Advanced Terrain Rendering:
  • Radial clipmap geometry for seamless level-of-detail.
  • Cascaded shadow maps for realistic lighting.
  • Specialized material system for CORINE Land Cover.
  • Ambient occlusion
  • Atmospheric fog with sun glow (Mie scattering / halo)
  • Triplanar detail texturing (rock, grass, forest, ice)
• Mobile & PWA:
  • Device orientation sensor control (quaternion-based)
  • Touch input with pinch zoom and double-tap
  • Geolocation for automatic positioning
  • URL-based state sharing (?lat=…&lon=…&alpha=…&beta=…&zoom=…)
  • Installable PWA with service worker for offline support
• Data Processing Tools:
  • Tile Extraction: Pipeline to extract and regularize map tiles from GeoPackage databases (Corine/extract_tiles.exe).
  • Polygon Processing: Robust clipping, splitting, and triangulation of complex land cover polygons.
  • OSM Integration: Augments land cover data with high-precision water bodies from OpenStreetMap.
  • Static R-tree: Spatial index integration for accelerating polygon triangulation operations.
  • Custom WASM modules: Performance-critical data decoding (decompress_tile.wat, decode_clc.wat), offloaded to a web worker pool.

Project Structure

The codebase is organized into modular components:

• src/lib (Core): Platform-agnostic core logic, math libraries (Matrix/Vector), IO abstractions, and terrain algorithms.
• src/web (Web Client): Primary browser-specific implementation using Brr, managing WebGL state, input, and networking.
• src/sdl (Native Client - Legacy): Desktop implementation using Tsdl and Tgles3 (legacy support).
• Corine (Tools): A suite of command-line tools for processing geospatial data, polygon validation, and generating tile assets.
• assets: Terrain detail textures in PNG and KTX2 compressed formats.
• data: DEM tiles, CLC tiles, points of interest.

Build Instructions

The project uses dune as the build system. OCaml is compiled to both JS and WASM via js_of_ocaml / wasm_of_ocaml.

Build all targets:

dune build

Web client specifically:

cd src/web && dune build

Data Sources

1. DEM: 30m resolution Copernicus Digital Elevation Models.
2. DEM: 10m resolution RGE ALTI.
3. Land Cover: CORINE dataset processed into triangulated optimized tiles.
4. Water: OSM water polygons fetched and merged for higher precision coastlines and lakes.

License

This project is licensed under the MIT License - see the LICENSE file for details.