Hey everyone, here we are again with our high-poly to low-poly tutorial. In this section I will be giving you a few tips on how to use Zbrush effectively as well as how to export your high-poly model and import it into 3D-Coat to be retopologized.
To begin, we need to discuss the DynaMesh. DynaMesh is ZBrush’s newest base mesh generation tool. DynaMesh is a perfect solution for free-form sculpting because it removes all need for focusing on topological constraints. It’s possible to change the overall shape of any DynaMesh by pushing or pulling, adding various pieces of geometry to combine into one, or even removing geometry in a manner similar to what you can do with Boolean operations. DynaMesh has been designed to create low and middle resolution sculpting stages, making it a perfect way to create your base mesh before diving deeper into all the powerful traditional ZBrush sculpting and editing tools. DynaMesh is truly analogous of sculpting with traditional real-world clay. As you add volume to clay by stretching out details or laying on strips of new clay the actual consistency of the material remains exactly the same. So no matter how much volume you add, you still have the same capacity for sculpting. DynaMesh accomplishes the same thing, maintaining the uniform resolution and polygon distribution of your mesh. This is very unlike traditional sculpting methods which result in stretched polys if you push the surface too far – something that hampers your ability to do anything more with the surface in those areas. DynaMesh will truly free your sense of creativity.
I showed you how to create a DynaMesh in part 1 of this tutorial. I just felt that I needed to explain its purpose a bit more before I got too far ahead of myself. Remember, in order to maintain a good mesh geometry with dynamesh, you need to update the mesh as you go by pressing the ctrl button and right mouse clicking in the workspace. This will automatically retopologize your DynaMesh.
Now a word on masking, which is an absolute necessity if you do not want to ruin what you have already sculpted. With the Lambkin I created her face before I decided to pull he hair out of the mesh. If I did not mask her face I would end up pulling her face along with the hair. The mask prevents you from affecting the geometry it covers. In order to mask a portion of your mesh hold down the ctrl button and paint on the surface of you mesh. The darkness that will appear on you mesh is the mask. If you want to unmask your work simply hold down ctrl and right mouse click in the workspace.
Subtools are another valuable tool you should be aware of in ZBrush. Subtools are kind of like layers in Photoshop; they allow you to add more than one mesh to your project. Each subtool can either be affected on its own or if you select multiple subtools and sculpt on them all together. I like to use subtools for adding eyes, clothes, hair or other decorative elements that require detailed sculpting.
Once you complete your sculpt with all the individual subtools you may then merge the subtools if you wish into one mesh that you will then decimate and export. Merging should only be done if you are sure that you want your final mesh to be all together. If you have a piece you want to remain separate than leave it detached from the main mesh and export it on its own.
In order for your mesh to be able to import into another program you will have to decimate it so that there are far fewer polygons than you original sculpt. Decimation lowers the polygon level without harming the quality of the final sculpt. It can take you from literally millions of polygons down to a couple hundred thousand. This saves your computer a lot of trouble and will help it to run smoother while you are in 3D-Coat.
Once you have decimated your mesh you can export it as an .obj file and import it into 3D-Coat to begin to retopologize your mesh. We will get into that more in part 3 of this tutorial.