Digital sculpting is a powerful and creative way to model organic and hard-surface objects in 3D. But what if you want to use your sculpted models for animation or game engines? You need to export and retopologize them to optimize their performance and quality. In this article, you will learn how to do that in six steps.
The first step is to decide which format you want to export your sculpted model in. Depending on the software you use, you may have different options, such as OBJ, FBX, STL, or ZTL. Each format has its advantages and disadvantages, such as file size, compatibility, and level of detail. You should choose the format that best suits your target platform and workflow. For example, if you want to animate your model in Blender, you may prefer FBX over OBJ, because it can preserve more information, such as materials, UV maps, and rigs.
STL is for 3D printing also known as Standard Tessellation Language. It contains only the surface information/geometry of an object. If organic they need to require a higher poly count as smooth groups and other information are not present. OBJ can contain object oritantation, materials but is limited compared to FBX. A ZTL file is a format for ZBrush and is specific to Pixel Logics engine.
The second step is to reduce the number of polygons in your sculpted model. Sculpting usually creates very high-poly models, which can be too heavy and slow for animation or game engines. You need to lower the polycount to make your model more manageable and efficient. There are different ways to do that, such as using decimation, remeshing, or baking normal maps. You should try to preserve as much detail as possible, while eliminating unnecessary or redundant polygons. You can use tools like ZBrush's ZRemesher or Blender's Decimate Modifier to help you with this process.
ZBrush has Decimation Master which can lower the polys while maintaining the integrity of the mesh. Simplygon by Microsoft has a robust plugin for both MAX and Maya that can poly reduce and bake normal maps for your mesh. PiXZY can convert many CAD file format files, correct errors, preserve curvatures. Export FBX and OBJ file formats.
The third step is to retopologize your model. This means to create a new mesh with a better topology, or the arrangement of vertices, edges, and faces. A good topology is important for animation and game engines, because it affects how your model deforms, animates, and renders. You want to create a topology that follows the shape and flow of your model, with evenly distributed quads, clean loops, and minimal poles. You can use tools like ZBrush's ZSphere or Blender's Retopoflow to create a new mesh over your sculpted model, or use automatic retopology tools like Instant Meshes or ZRemesher.
The fourth step is to UV unwrap your model. This means to map the 3D surface of your model onto a 2D plane, so that you can apply textures and materials to it. UV unwrapping is essential for animation and game engines, because it determines how your model looks and interacts with light and shadows. You want to create a UV map that minimizes distortion, stretching, and seams, while maximizing the use of space and resolution. You can use tools like ZBrush's UV Master or Blender's UV Editing Mode to create and edit your UV map, or use automatic UV unwrapping tools like RizomUV or Unfold3D.
The fifth step is to bake your maps. This means to transfer the details and information from your high-poly sculpted model to your low-poly retopologized model, using different types of maps, such as normal, displacement, ambient occlusion, or curvature. Baking maps is important for animation and game engines, because it allows you to recreate the appearance and depth of your sculpted model, without using too many polygons or resources. You want to bake maps that are accurate, crisp, and seamless, while avoiding artifacts and errors. You can use tools like ZBrush's Multi Map Exporter or Blender's Bake Mode to bake your maps, or use external software like Substance Painter or Marmoset Toolbag.
The sixth and final step is to test your model. This means to import your exported and retopologized model into your animation or game engine of choice, and see how it looks and behaves. Testing your model is important for animation and game engines, because it allows you to check for any issues or improvements that you may need to make. You want to test your model for factors such as scale, orientation, rigging, skinning, animation, lighting, shading, and performance. You can use tools like Blender's Eevee or Cycles Renderers, or game engines like Unity or Unreal Engine, to test your model and adjust it as needed.