ZBrushCentral

Newbie Question - Wall Texture w/ Photographic Source?

Hi, I am a zbrush newbie so bear with me if this stuff seems obvious. I would like to take a photographic source - say a picture of a concrete wall, with cracks and pits and such - and turn it into a wall texture for use in a per-pixel-lighting game engine, with the photographic source as the diffuse channel and a normal map based on the photographic source for the normal map channel. While there are other methods of doing this (the nvidia normal map tool, etc.) I would really like to get some zbrush type action going on to see if it produces better results.

There are two ways I have tried this in Zbrush and neither has worked. I’ll describe the problems with each of them but if there is another way I have not considered please let me know!

1. Photograph -> Greyscale -> Z channel in Zbrush

I would like to use a greyscale version of the photograph (prepared in photoshop) as a basis for further tweaks in Zbrush but I can’t figure out how to get Zbrush to load the greyscale image into its Z channel. Essentially what I want to do is this:

a. import RGB image -> RGB channels in Zbrush
b. import greyscale image -> Z channel in Zbrush
c. edit the Z channel in Zbrush
d. export Z channel information as a normal map

I can’t figure out how to do b.

The other method I tried was this:

2. Greyscale image -> import as Alpha in Zbrush -> polymesh

but no matter what I do (various smoothing/resolution settings when generating the polymesh, etc.) the mesh always comes out pock-marked, with little spots where vertices are inexplicably much higher or lower than their neighbors, where no such micro-peaks or valleys exist in the image.

Even if I fixed that problem though, how would I align the mesh back up with the original photograph so I could see it as I made further edits, and so that it would export a normal map at the end that lined up correctly with the diffuse component?

Thanks for any help.

If you’re using ZBrush 2, I would import the greyscale image into the Alpha channel, then press Alpha>Crop and Fill. The layer will be filled with depth, as specified by the alpha. You can then adjust that depth by sculpting on it. Next, whatever material slot you used for the fill operation, make sure that it’s selected and load the NormalMapping material that’s included with ZBrush. It will overwrite the document, and you can then use Texture>Grab Doc to capture the canvas as a normal map.

That was it, thanks a bunch.