Summary from Crydev Forum > Community > Tutorials > Texture Maps From Diffuse:
I was getting annoyed by generating normal map out of diffuses since they bend according to the color information I was getting unclean and plastic like normal maps ... This is useful if you want a really clean normal map and also the sad part it this tutorial works only for "some" diffuses, by "some" I mean the ones with simple surfaces.
Of course it works for all type of diffuse but that requires a digital pen and a lot of time to put in.
- Open it up in Photoshop (or other software).
- Make another layer on top of it, fill it with black and set the opacity to 50%.
- With the black layer activated you are now able to see the below layer which is our diffuse, now select the areas you want to bump up, and fill them with white color.
- Once you are done with it, set the opacity to 100% and save the image
- Save it and generate a normal map out of it.
- With the clean normal map, you can also simply generate a clean Specular map. (This if you NEED a clean specular, otherwise spec from original diff would be good).
- Remember to copy the black and white diffuse into the alpha channel and that'll simply be a Displacement map. (blur it according to your own surface type, rocks benefits from this, hard metal shapes probably not.).
- Specular maps shouldn't have strong AO or shadows in them, since when the light direction changes, it might look way off. Especially notable on the right-side (Opposite of the light direction) where the inwards-bending parts should be brighter than the surface itself. The normal-map should also contain some smaller details from the diffuse map, creating an more detailed outlook, you should try experimenting with creating an down-scaled normal layer and up-scaling it, blurring and overlaying on the main layer.
- Also, add a glossiness map to specular alpha, so that you can have dirty parts reflect light worse than clean parts.