Rotate a tangent space normal map?

malcolm

Is there a tool for this yet, one of our artists wanted to repack a normal map uv island without having to rebake the asset, is there any way to rotate a high to low tangent space map in Photoshop?

m4dcow

Maybe this thread might help:
http://www.polycount.com/forum/showthread.php?t=103926

EarthQuake

In max you can apply a tangent space normal map, and bake it onto a new uv set. Though this will "bake in" any smoothing errors etc that you would get from say, loading an xnormal baked map and applying it in max. So probably not a good idea unless your source content is baked in max.

You can bake it as a diffuse map from one uv to another uv set in most apps and then use the scripts in m4dcow's link above.

Though really, if your source content is the same resolution, and you've repacked for a more efficient UV layout, the only thing that makes any sense is re-baking it. If you've got 2x2x or 4x4x res source bakes, then it won't be an issue I guess.

Rebaking the normal shouldn't be that time consuming though really, right? I mean it takes time to set up a bake to transfer the uvs, and it takes time to make selections and run the scripts and double check it was all done correctly. Maybe not that much time, but really rebaking a normal map shouldn't be that time consuming either, and usually it would be less hassle, ie: set up the bake, if its a super dense mesh or something do another task while its actually baking.

If doing a rebake is a huge time sink, the better Q to ask might be why does it take so long for us to set up bakes?

cptSwing

If you dig around the wiki, there are some photoshop actions for rotating normal maps if I'm not mistaken. And I seem to remember nDO being able to recalculate the normal maps from within PS if you rotate pieces.