I have two triangled meshes -- the one (say, A) at a higher resolution, the other (say, B) at a lower resolution.
I know normal and vertices coordinates for both (and texture coordinates as well).
I'd like to extract a normal map from the latter on the basis of the former.
I already have a mapping from the points of B's surface into the uv space.
I guess I have to calculate a tangent space for every * pixel * of B's map (on the basis of the corresponding point on
B's surface -- am I correct here?)... And ok, I know how to do it.
Then, for assegning each pixel of the map a color... How should I use the information I've got about A's geometry?
Just want to ensure, that you know, that there are already (free) tools available which do exactly this, like xnormal or blender. No need to reinvent the wheel. If you really want to reinvent it, then take a look at xnormal/blender documention for some hints or at the blender source code (it is open source).