Hi everyone
i have an issue with xnormals and smooth groups
an image will explain everything
http://s2.noelshack.com/old/up/xnormalsucks-45758f2f14.jpg
I’ve used CreaseImport from Zbrush to import this mesh and subdiv it , but as you can see , on the circle polys , it generates a weird artefact , do you know how to fix that ?
your UV’s mesh don’t support a normal map of that type. You’re asking your normals to do more than they can. You’d want to bake that object using a cage and shrink the edge of that cylinder so it doesn’t over lap those areas. Or you can increase the number of edges so they better support the shape of the HP object.
I’ve studied how projection and normal map work, but it’s the first time i’m trying to generate normal map for this kind of shape => here is the last UVs
http://s2.noelshack.com/old/up/xnormaluv-12d361aa54.jpg
I’ve even tried with a cage , it didnt work better 
I’ve tried changing the UVs configuration
http://s2.noelshack.com/old/up/xnormalwtf-5a0ad9eb29.jpg
but it doesn’t work neither 
If it’s just impossible, please, tell me how you would do to generate a normal map for this kind of shape.
Normal maps only affects the way the “light” appears to be coming off the object. Like the light is bent on a hot day, only in a specific way to get the effect you want. It does not change the outline of a object or its number of polygons. So when you try to take a smooth tube and put its normal on a blocky tube the blocky tube will have the shadows of the smooth tube, but it will still have a blocky outline.
(Your seeing a weried shaddow at the end because of the difference in smoothness. Its checking the difference between the two, and drawing a “shaddow” to try to show the difference. Only the difference is to great for a “shaddow” to show.) So hide the ends of the tube, delete that part of the normal map on the ends of the tubes, or make the low polly smoother by adding more geometry.
That’s the best I can do.
:lol: I know that it’s fake bump thank you 
I know about tesselation too (which is real polys but my graphid card can’t handle DirectX11 and it’s still useless for GameArt)
And I know how to make complex shapes too (yes , I look like a noob with my tube , but it was just a test to show you clearly what’s going wrong :D)
But the issue is not about my skills , the issue is about how to fix this artefacts , thank you for your tips , im going to wait more for other answers that might be useful to everyone
The problem comes from the curve of the object and how normal maps are a raycast from a normal vector.
The proper type of cage is displayed in this image. In order to avoid the artifacts you need to ensure your mesh is going to cast and hit a surface.
I don’t understand why you’re trying to push a normal map on a cylinder anyway…but hmm, maybe I don’t see something you don’t.
Anyway…if you have any questions about the image just ask.
Nice picture, is there a way to increase the cage size in Zbrush anymore? (Zmapper got the boot, and the settings seemed to too.)