1. “Perspective Based Level of Detail Management of Topographic Data” By: Morten Granlund Supervisor: Gunnar Misund http://www.ia-stud.hiof.no/~mortengr

2. Level of Detail “Easing the burden of the 3D renderer…”

3. The basics of Level of Detail GOAL: Render 3D graphics fast! GOAL: Render 3D graphics fast! SOLUTION: Several levels of detail. SOLUTION: Several levels of detail.

4. More on LoD One square has a fixed data-size A model is more accurate if: a)T he model has more squares. b)E ach square covers a smaller area.

5. Tree Structure Level 0Square covers >200 km Level 1Square covers 100-200 km Level 2Square covers 50-99 km   zoom

6. Rez… …is an Open Source framework for translating terrain data. …is an Open Source framework for translating terrain data. …creates Level of Detail hierarchies. …creates Level of Detail hierarchies. …creates two parallel hierarchies: …creates two parallel hierarchies: TilesTiles TreesTrees model tiles trees

7. Tiles Tree containing VRML data. Each node is called a tile. Each tile contains a matrix with heights (elevation grid). 0 1 2 3 4 Wo rld.wr l tiles

8. Trees The Trees hierarchy contains the structure. The trees structure consists of a file hierarchy parallel to the tiles. A trees node is a “wrapping” around each tile. 01234 Wo rld.wr l 01234 trees Wo rld.wr l

9. A “Trees”-node has: Reference to Parent node Reference to Children nodes (x4) Reference to the terrain data (tile node) 01234 tiles Wo rld.wr l 01234 trees Wo rld.wr l