The highpoly mesh doesn't have to be unwrapped. It does have to fill the same space that the lowpoly mesh does and be the same size, as there is no way to align or resize the 2 meshes in zbrush.
This is how you use zmapper to create a normal map assuming that the mesh you brought into zbrush in the3 first place is not the low poly mesh you wish to generate a normal map for. Load high detail ztool Open Zmapper Go to the "projection" tab "Capture current mesh" Load low poly ztool/import lowpoly mesh (unwrapped…
As another zbrush newb, I would be interested in the answers as well. I can share one discovery of my own.. Finish COMPLETELY your current sub-d level before going to the next. Going back and forth too much can start to ruin your details at higher levels. (Yeaa, you have the target mesh already unwrapped).