An interactive WebGL terrain visualization maps grayscale heightmap data onto a 3D plane, displacing vertices via a custom Three.js `ShaderMaterial` and `vertexShader`. The fragment shader blends repeated textures (ocean, sand, grass, snow) using elevation-based `smoothstep` intervals, while D3 loads CSV height values. Users can orbit, zoom, and pan with `OrbitControls`, and the scene exports geometries through `GLTFExporter` or `OBJExporter`.