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CSE 681 Texture mapping - other methods Environmental mapping Bump mapping.

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Presentation on theme: "CSE 681 Texture mapping - other methods Environmental mapping Bump mapping."— Presentation transcript:

1 CSE 681 Texture mapping - other methods Environmental mapping Bump mapping

2 CSE 681 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

3 CSE 681 Environmental Mapping Reflect the environment off an object Procedurally Reflection_color = f(R(u,v)) Table look-up Reflection_color = table(R  (u,v),R  (u,v)) Use normal to index into texture that represents the environment

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

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

6 CSE 681 Environmental Mapping table construction by projection

7 CSE 681 Hemi-cube projection construction method

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

9 CSE 681 Hemi-cube reflectance look-up

10 CSE 681 Examples

11 CSE 681 Examples

12 CSE 681 Examples

13 CSE 681 Examples

14 CSE 681 Examples

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

16 CSE 681 Bump Mapping 1.Use grey-scale image to define height field 2.Compute gradient of height field 3.Use gradient vectors to modify normal Don’t really modify surface geometry – just pretend we do by modifying normal

17 CSE 681 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) + =

18 CSE 681 Bump Mapping Normal Vector O(u,v) B(u,v) O’(u,v) + = Display:

19 CSE 681 Bump Mapping

20 Bump Mapping Normal Vector

21

22 CSE 681 Bump Mapping Normal Vector Assume B is small - too small to deal with

23 CSE 681 Bump Mapping Normal Vector = N = 0= D(u,v)

24 CSE 681 Bump mapping examples

25 CSE 681 Bump Mapping Example


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