I am receiving an error when trying to unwrap a model using UV master “Unwrap not performed because the mesh contains closed shells! Open them or disable ‘UseExistingSeams’.” Any idea how to fix this? And what is a closed shell? The mesh is a human made in Maya with UV’s made for face and eyeballs in maya only. I usually do this for characters and then auto wrap in Zbrush for the rest of the body and never have had this problem. When I hit “flatten” under uv master the uv’s for face and eyes are correctly imported, however they are flipped upside down, not sure if that is related. Any help would be greatly appreciated!
It sounds to me like you don’t have any seams for uv master to use to unwrap the model with, hence the closed shell error. Since you have use existing seams turned on uv master cant add any new seams to unwrap with. So simply take it back into maya and place all the seams where you want them and then try uv master again or uncheck use existing seams in zbrush and use uv master’s auto unwrap or protect/attract tools to try to control where the seams will placed.
Also, zbrush works with the uv space differently than most programs which is why you are seeing the uvs flipped. This is not a problem, but just keep in mind that you may have to flip the textures once you are back in maya/prior to export from zbrush. However, I believe with zbrush 4 it may take care of this for you already.