hi I have to deliver a normal map based on a mesh I may not change 
It is quite low res, and has sharp edges. The sbrush version looks fine, but exported the map is screwd and almost useless, I have to manually paint the problems away.
I would say it is based on the sharp edges of the model, but maybe not.?
thanks
When you actually apply the map to the model in your renderer, how does it look?
If it doesn’t look good when rendered, please provide information about the steps and settings that you used when importing, dividing, detailing and then creating the normal map. The more info you can provide, the more likely it will be that a solution can be found.
render has sharp edge (looks quite different than in zbrush)
steps:
import obj
split into polygroups by uv sets
store morph target
divide to lvl 9
sculpt with stencils mainly
low res version, switch to morph target
create 4k 32 bit normal map via multi displacement 3 from lowest level morph
difference between 4 and 0 subsamples is visible, burt the sharp edges stay
rendering set up with smooth uvs off (XSI Mental ray)
Try xNormal (www.xNormal.net.) (yeah, I know, not Zmapper.) You may be able to fiddle with the how the scan that is generating the normal from base mesh to high-freq detail. It’s free.
I would look into my UV’s in the region on the base mesh to see if there is anything funny there that might be inducing the odd edges when Zmapper raycats to the base mesh.
-K
I will have a look at that…
For the Uvs: I checked them twice, I still suspect the edgy low res mesh, butu I may not change it…