Bump mapping

[leigh]

Filters aren't going to work. They add in fake lighting effects, which are absolutely not going to give you a proper bump map. I've never used Crazy Bump so I can't comment on that.

The fact is that you can't always expect a diffuse map to work as a bump map easily. This is because bump maps work by making light areas appear raised, and dark areas appear indented. You can't be sure that your colour map is going to do this without some touching up work. It's a common fallacy that you can simply desaturate a colour map and use it as a bump map, because it assumes that all the dark areas of your colour map should be indented, and all the light areas raised. Occasionally, this may happen by pure coincidence, but you can't rely on it for sure. In the image you're showing, simply desaturating it is going to make all those light splotches raised, which isn't actually the case on the real wall at all.

Having said that, your bump map should always have some relationship to your colour map, so the colour map is a good place to start. I usually take it and then use the High Pass filter in Photoshop. This evens out the grey values nicely. I then do any inverting and painted touch ups that are required.

[leigh]

Here's a rough two minute example from your image. As you can see, the drips and such shouldn't affect the bump map, as the surface is a rough concrete of some kind. As such, simply ensure that the surface retains the roughness (I cloned it around a bit), but doesn't have the details that only affect the colour (and specular) of the surface.

http://www.leighvanderbyl.com/temp/bumpMap.jpg

[IRAFK]

wow, thanks leigh for that mini tut. you helped me out. :buttrock:

[mernor]

leigh, this was just amazing I really appreciate your help with that. So basically what you are saying is that each bump map is really individual and the best case is to consider the nature of the matterial when creating it. BTW How did you accentuate the bricks in the bump ?!?

[leigh]

leigh, this was just amazing I really appreciate your help with that. So basically what you are saying is that each bump map is really individual and the best case is to consider the nature of the matterial when creating it.

Yup, that's it. As I said, sometimes you can get away with minimal work, but generally some touching up/cloning/painting is required.

The High Pass filter is very useful though, especially with the slider more on the left hand side. It creates crisp details that work really well for bump maps, and even displacements.

BTW How did you accentuate the bricks in the bump ?!?

I used the Burn tool a bit on the dark lines, to ensure their shape was represented correctly.

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