As is shown above ,I used UV master but it is not the thing that I want.For topology,each one of a single scale is barely a cylinder and I know how to unwrap a cylinder,but apparently I have no idea of how to unwrap a set of cylinders. I know there must be a very eazy and handy way to achieve it.
Hopefully someone would help me with this .Thank you very much!!!
1- You have to unwrap one of the scales before turning it into an IMM brush. Once you have a mesh with proper UVs, you can turn it into a new IMM, and a NanoMesh Brush.
2- Then you also have to unwrap the UVs of the surface you will apply the NanoMesh to. You can use UV Master for that job.
3- Once both of your meshes have UVs, you should apply your NanoMesh on the surface.
4- In order to preserve all the UVs you had on the mesh, you have to go to the NanoMesh menu on the right and hit “Edit Mesh.” Once you’re in edit mode, go ahead and apply a random texture to it via the “Texture Map” menu on the right. Then go back to the “Nano Mesh” menu and exit the edit mode via turning off the “Edit Mesh” option.
(I know that this is a bit weird operation. Normally textures have no relationship with UVs of a mesh in the 3D pipeline, but ZBrush works a bit differently. So we have to assign a texture to it in order to keep the UVs)
5- Adjust your NanoMesh in whichever fashion you want.
6- If you want all of your nanomesh instances to share the same UV coordinates, you don’t have to do anything else. Just press the (One to Mesh) button under NanoMesh => Inventory.
But if you want the polygons to occupy the same UV areas with the polygons of the placement(surface) mesh in the UV map, use the “Use Base Mesh UVs” option under NanoMesh => UV.