1. Texture mapping - other methods
CSE 681

2. Review Surface Texturing
u,v mapping: map 3D point within 3D surface
Quadrilateral: inverse bi-linear mapping
Spherical: e.g. lattitude-longitude
Triangulated: barycentric coordinates
Mip-mapping: pre-filter texture map
Average texels, reduce resolution
Index into appropriate map based on projected pixel size
CSE 681

3. Environmental Mapping
Reflect the environment in on an object
Use normal to index into texture
Procedurally
Reflection_color = f(R(u,v))
Table look-up
Reflection_color = table(Rq(u,v),Rf (u,v))
CSE 681

4. Procedural Environmental Mapping
Simple: ray up is blue, ray down is brown
Medium: use sinusoidals to interpolate between gray and silver for a chrome effect
Complex: compute fractal intersection
CSE 681

5. Environmental (table-based) Mapping
Use pre-constructed enclosing volume containing projected environment
Hemi-cube or hemisphere
Mip-mapping possible
CSE 681

6. Environmental Mapping table construction by projection
CSE 681

7. Hemi-cube projection construction method
CSE 681

8. Hemi-cube image construction method
Use pictures - of sky, mountains, buildings, etc.
CSE 681

9. Hemi-cube reflectance look-up
CSE 681

10. Examples
CSE 681

11. Examples
CSE 681

12. Examples
CSE 681

13. Examples
CSE 681

14. Examples
CSE 681

15. Bump Mapping
Modulate normals over surface to create visual effect of geometric detail
CSE 681

16. Bump Mapping Use grey-scale image to define height field
Compute gradient of height field
Use gradient vectors to modify normal
Don’t really modify surface geometry – just pretend we do by modifying normal
CSE 681

17. Bump Mapping
Surface is displaced in direction of normal according to displacement in bump table, B(u,v)
O(u,v)
B(u,v)
O’(u,v) + =
B is height field
O is original surface
O’ is bumped surface
Need normals of bumped surface
CSE 681

18. Bump Mapping Normal Vector+ =
B(u,v)
O’(u,v)
O(u,v)
B is height field
O is original surface
O’ is bumped surface
Need normals of bumped surface
Display:
CSE 681

19. Bump Mapping CSE 681 B is height field O is original surface
O’ is bumped surface
Need normals of bumped surface
CSE 681

20. Bump Mapping Normal Vector
B is height field
O is original surface
O’ is bumped surface
Need normals of bumped surface

21. Bump Mapping Normal Vector
B is height field
O is original surface
O’ is bumped surface
Need normals of bumped surface

22. Bump Mapping Normal Vector
Assume B is small - too small to deal with
B is height field
O is original surface
O’ is bumped surface
Need normals of bumped surface
First term is N, last term == 0
CSE 681

23. Bump Mapping Normal Vector
B is height field
O is original surface
O’ is bumped surface
Need normals of bumped surface
First term is N, last term == 0
= N
= D(u,v)
= 0
CSE 681

24. Bump mapping examples
CSE 681

25. Bump Mapping Example
CSE 681