Baking normal map from one UV to another

Victorcg

Hello. I have a question.
I have 2 UV layouts and I need to bake normal map from one UV to another. I can't bake it like simple color, of course. Any suggestions?
Any 3D software.

Scruples

1. Put the normal map texture into the color channel
2. ????????????
3. Profit?

...oh wait, that won't work I am an ass, I forgot how dependent tangent space normal maps were on UV orientation.

The only way I could imagine doing this is by converting the tangent space normal map to object space before transferring it to the other UV set. Xnormal is the only software I know of with this feature.

tristamus

It doesn't matter what the UV Layout is of the low-poly....If you have 1 model with 2 different UV layouts, the normal map will bake to them the same regardless.

As long as the uv's are laid out properly.

Neox

i think there was someone here who did that for maya, recalculating the normals based on uv rotations, not sure anymore who it was - maybe Brice?

Scruples

Result in Maya's viewport...without first converting to object space normals, just rotated UV and Texture 90 degree's.
At this point I have to point out baking from high poly is probably easier.

Victorcg

tristamus wrote: »

It doesn't matter what the UV Layout is of the low-poly....If you have 1 model with 2 different UV layouts, the normal map will bake to them the same regardless.

As long as the uv's are laid out properly.

I need to bake tiled normal map into another UV. I can't bake it from high poly.

ablaine

Use xNormal.

1. Set the lowpoly you're baking the existing normal map from as a high definition mesh, then right-click in the next column over and add a "base texture to bake." Select your normal map texture as the bake texture, and click OK. Ensure that "Base Texture is a tangent-space normal map" column is checked.

2. Set the lowpoly you want to bake the normals to (with the new uv layout) as the low definition mesh.

3. Under Baking Options, choose "Bake Base Texture."

4. Set the size of the output file and pick a name to save it as and then click the "Generate Maps" button.

xNormal rules!

cptSwing

^ awesome, always wondererd whether xNormal could do this.

S_ource

I think you can do something like this in max put the normal map in some map slot on one model and bake the information to another models texture?

cptSwing

The real trick is to recalculate the normal map shells that are being rotated. Pretty sure Max doesn't do that.

Noors

http://www.polycount.com/forum/showpost.php?p=1366692&postcount=7

Yeah it only works if you RTT a copy of your object with the normal in the bump channel.

Mark Dygert

S_ource wrote: »

I think you can do something like this in max put the normal map in some map slot on one model and bake the information to another models texture?

yea RTT will capture bump/normal data on the source model (normally the high poly) and project it onto the target (normally the low poly).

If you only have low poly to work with you apply the normal map and treat that as the high poly, you then copy your model and treat that as the low poly and bake.

The results are going to be slightly degraded and rebaking from the high poly source will always be better but sometimes you have no choice.


Side note: Your baked details don't always have to be geometry. Adding a bump or normal to your high poly can be a good way to bake out extra details that can be hard to model, like chunky text that has been chipped up or worn down, scratches and scuff marks, some channels or groves ect...

Victorcg

Thank You for such great answers!