90 likes | 200 Views
“Perspective Based Level of Detail Management of Topographic Data”. By: Morten Granlund Supervisor: Gunnar Misund. http://www.ia-stud.hiof.no/~mortengr. Level of Detail. “Easing the burden of the 3D renderer…”. The basics of Level of Detail. GOAL: Render 3D graphics fast!
E N D
“Perspective BasedLevel of Detail Managementof Topographic Data” By: Morten Granlund Supervisor: Gunnar Misund http://www.ia-stud.hiof.no/~mortengr
Level of Detail “Easing the burden of the 3D renderer…”
The basics of Level of Detail • GOAL: Render 3D graphics fast! • SOLUTION: Several levels of detail.
One square has a fixed data-size A model is more accurate if: The model has more squares. Each square covers a smaller area. More on LoD
Tree Structure Level 0 Square covers >200 km zoom Level 1 Square covers 100-200 km zoom Level 2 Square covers 50-99 km
Rez… • …is an Open Source framework for translating terrain data. • …creates Level of Detail hierarchies. • …creates two parallel hierarchies: • Tiles • Trees model tiles trees
World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl Tiles • Tree containing VRML data. • Each node is called a tile. • Each tile contains a matrix with heights (elevation grid). tiles 0 1 2 3 4
tiles trees 0 1 2 3 4 0 1 2 3 4 World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl 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.
tiles trees 0 1 2 3 4 0 1 2 3 4 World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl World.wrl A “Trees”-node has: • Reference to Parent node • Reference to Children nodes (x4) • Reference to the terrain data (tile node)