Thanks for that. I see your point about the HDR, as 256 discrete steps covering a large displacement can't be solved through interpolation.
I'll note an optimisation I don't know if you're aware of or not. In the given example the greyscale image ranges from 0 to something like 128. In your bump displacement you set bump amount to -0.24. Now because the image intensity is only halfway of the maximum range (all BMP's range 0 to 1 for 0 to 255 scale, the actual range of displament is 0 to -0.12. If you load the bmp into PS and histogram it to the full range of 0 to 255, then set the RS bump to -0.12, you get the same level of displacement but rendered much faster (alternatively you can load the texture and apply a curve in RS but the PS method has less overhead). That's because RS has to look for pixel displacements up to the maximum, whether you use that peak level or not. Setting a lower peak and ensuring your bumpmap covers the full spectrum makes a big difference. David Coombes [EMAIL PROTECTED] ... > Here's the project, including both textures (readjust the paths): > http://www.xs4all.nl/~ath8n0r/div/HDRdisplacement.zip > > -Mark H >
