How to bake normal map for subdivision model

Suggorath

I need advice on how to properly bake a normal map for a subdivision model (not LP) because, if I create a normal map from HP on SubD (0), when I later apply level (2) to the SubD model, the UV map changes and the texture doesn't fit, not to mention the influence of the model not being triangulated. The type of subdivision can be OpenSubD or Catmull-Clark or UV smoothing, etc.

ZacD

Probably going to need to lock the normals (not sure if that's even possible) or use an object/world space normal map.

I don't see that workflow working very well in either case. 

poopipe

Bake to the model you intend to render - anything else is guaranteed to give you incorrect results,

Suggorath

I'm asking because I don't know the procedure to create textures, since applying the Subdivision level changes the UVs and creates seams, not to mention that I can't triangulate such a mesh and the normal map will be baked incorrectly , so then how are textures created ? There must be a correct workflow, for example, when you have a head model, basic subdivision, rigged, and textures created for the basic subdivision level, but as soon as the model is subdivided, everything gets messed up.

EarthQuake

Generally, you should subdivide your low poly to the intended or target sub-d level for the final renders. So if you intend to use level 7, bake with that. When you preview it with other sub-d levels it will be slightly incorrect, but it should be optimal for the final use case.

This applies to other baked maps like height/displacement as well.