Chapter 3: Methodology

3.1 Overview

• FlatBuffers overview
• File structure
• FlatBuffer schema
• Header
• Spatial index
  • Hilbert sort
  • Packed Hilbert R-tree
• Attribute index
  • requirements for attribute index
  • Eytzinger layout
  • Static B+Tree
  • Payload and offset byte management
• Feature encoding
  • Geometry encoding
    • Boundaries
    • Semantic surfaces
  • Attribute encoding
  • Appearance/Material/Texture encoding
  • Geometry template/instance encoding
  • Extension encoding
  • Feature
• HTTP range requests
• Works on browser (WASM build)

3.2 FlatBuffers Overview

• Brief introduction to FlatBuffers and zero-copy parsing
• General workflow of FlatBuffers schema and compilation
• Data types and restrictions

3.3 File Structure

• Magic bytes
• Header
• Spatial index
• Attribute index
• Feature encoding

3.4 Spatial index

3.4.1 Hilbert sort

3.4.2 Packed Hilbert R-tree

3.4.3 Attribute index

• requirements for attribute index
• Eytzinger layout
• Static B+Tree
• Payload and offset byte management

3.5 Feature encoding

• Geometry encoding
  • Boundaries
  • Semantic surfaces
• Attribute encoding
• Appearance/Material/Texture encoding
• Geometry template/instance encoding
• Extension encoding
• Feature

3.6 HTTP range requests

• Partial fetch with HTTP range requests
• Works on browser (WASM build)