Generating Bump-Map Textures for PVR

[PH3NOM]

Mainly directed towrads BlueCrab, but anyone feel free to add your input.
There is a KOS example pvr/bumpmap/ showing how to use the Bump-Map feature of the PVR ( thanks BlueCrab for adding that ).

My question is how do we generate the Bump-Map textures from the base texture?
It seems to be a greyscale version of the base texture, but I am not quite able to get the same results by playing with the base texture in Photoshop.

Thanks in advance.
-Josh

[BlueCrab]

The image used for the bumpmap is not just a greyscale version of the input texture. It is more a representation of the change in surface normals for the input texture. The best suggestion I can give is to take a look at the dcbumpgen code in the utilities. I didn't actually write that code, nor did I create the images used as the example data. They were both submitted to the KOS mailing list more than 10 years ago!

The texture that dcbumpgen generates (and that is fed into the hardware) represents the surface normals for the texture. Specifically, it represents the S (elevation angle of the surface normal 0-90°) and R (rotation angle of the normal 0-360°). The patent document for the bumpmapping hardware is also somewhat useful to look at here, and I've attached it to this post.

Also, for reference, this is the original post on the KOS mailing list where the information was posted.

[Dev]

http://www.crazybump.com/

[bogglez]

Isn't the input just a heightmap? In blender you can put the base texture on a quad, turn the quad into a grid of the appropriate resolution, change the height of vertices and export the geometry as a heightmap which you can then use as input for dcbumpgen I think