Texture baking is grabbing some textures from the wrong areas

Question

I'm currently trying to bake my textures onto a model for exporting it to Unity3D. Lighting is set up as normal, and a joined copy of the model has been created via duplication, in the exact position as the original version.

However, it seems that during the bake process, the roof texture is being flipped with the chimney texture;

https://i.stack.imgur.com/sDPDT.jpg

It looks like it's almost baking the texture map that's looking down the chimney, rather than a straight flip? Following this then, the side of the chimney is displaying the roof tiling texture.

The above is with a ray distance of 1. Setting ray distance to 2 seems to magnify the effect, while setting it to 0.5 seems to make it slightly better. However, going much lower than this results in a lot of artifacting.

Would anyone have any ideas on how you can work around this?

Answer 1

You can add a Split Edge Modifier (for hard edges) and a Displace Modifier with a very small Strength value so that your target mesh will be slightly above your source. Now you should get a better result with a low ray distance.

If you still get artefacts on your bake you will probably need to split the chimney from the house. You can just make copies, move the chimney on both the source and target, bake, and remove the copies. The drawback is that you wont get the correct shadows.

Hope that this was helpful.

Answer 2

I am not very experienced with texture baking, but it sounds like your problem is due to the pieces intersecting each other when the rays are traced.

If I understand correctly, baking a texture basically creates virtual cameras a certain distance away from the mesh and renders from them, onto the object. This is only because you are trying to bake detail from one mesh to another. If the meshes are the same poly count there should be no reason to do this, so that might be an easy way to fix your problem.

However, in your case, Blender is using the face normals to determine the direction of the rays. This could be inaccurate and it can be more precise if you create a cage mesh so that it can draw a ray from the cage mesh through the vertex of the master mesh, until it hits the low poly mesh to determine where detail should be draw.

It is also possible that the UVs overlapped or were messed up when you joined objects.

Sorry that this isn't a direct answer, but I hope I gave you some ideas.