I may sound stupid with this question but I hope you can answer it because I am confused. can we compair normal maps. like which normal maps or displacement maps give more details is it the one zbrush generates or Blender generates or are they the same or it depends on the details of the 3D sculpt
wel , in theory the disaplacement map will change the silhouette of your model after you have subdivided it quite a few times There is also the shader based version which does not need you to subdivide the model. Generally more used in CGI/VFX rendering. Normal maps do not change the shape of the model and work better with baking from a high poly model where the shape of the low poly matches the high poly quite well, more commonly used in games I tend not to bake normal maps from blender as the anti aliasing sucks, zbrush is ok, but I prefer xnormal
In an abstract sense a normal map is supposed to be unique for whatever mesh (I specify mesh rather than geometry to include the UVs and smoothing) it was baked from, and so is entirely dependent on the details in that mesh. However as stated above, programs can vary in the way they bake and render the normal maps, although often not enough to matter in my opinion. Certain metrics like bit depth, resolution and compression are quantifiable (see: https://polycount.com/discussion/148303/of-bit-depths-banding-and-normal-maps/p1 ). There are also best practices that contribute to better bakes (see some of the long running tech talk threads ). Ultimately however understanding the 'quality' of a bake is basically visual - you look at how it renders on your mesh and see if it looks gross or pretty.
For realtime engines, it's often the case that you need a normal map wherever you use a displacement map - Unreal for example does not recalculate normals when using World Position Offset, so you will need to provide the updated normals yourself, although this can be generated in shader.
Replies
There is also the shader based version which does not need you to subdivide the model. Generally more used in CGI/VFX rendering.
Normal maps do not change the shape of the model and work better with baking from a high poly model where the shape of the low poly matches the high poly quite well, more commonly used in games
I tend not to bake normal maps from blender as the anti aliasing sucks, zbrush is ok, but I prefer xnormal