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Category: Modeling

Modeling topics:

• Polygon Count

• Subdivision Surface Modeling

Topology

• Shoulder Topology

• Limb Topology

• Face Topology

Why is topology important?

Good topology is essential if you want fast framerates (realtime) and good deformation (both realtime and pre-rendered).

For realtime rendering, bad topology can create rendering problems. Long thin triangles can cause slower rendering. T-vertices can cause gaps or seams. A ton of vertex-splits can cause vertex cache misses. Etc.

What are the main principles of topology?

• Silhouette (triangles define the outer shape of the model, don't waste triangles where they don't add to the silhouette, depending on the requirements of the other priniciples...).
• Deformation (vertices and edges need to be in certain places to give good bending/compressing/stretching when the model is skinned or morphed).
• Triangle density (add more triangles where there's curvature, less where it's straight, but balance this by the needs of the other priniciples).
• Manifold surfaces (avoiding T-vertices, doubled faces, gaps, flipped faces, internal unseen faces, floating vertices, etc.).

• Splits (see this).

• Vertex normals for tangent-space normalmaps. Most game engines require a bit more geometry near areas that have a lot of change in angle (hard corners, etc.) otherwise the vertex normals fight with the normal map and create shading errors. Careful topology can minimize or avoid these errors altogether.

• Poles can create dimples or bumps in a subdivided surface, they should be placed away from areas that deform a lot.

What areas are the most important topologically for accurate animation?

Animation topology is the most important where the model has to deform the most. Crotch/hips/butt, shoulders/armpits, mouth corners/cheeks, knees, elbows, hands/fingers.

Are there any secrets for studying topology?

Not really. Just like any other discipline, learning about good topology usually requires making the mistakes yourself in order to experience first-hand what the results are, and how important it is to avoid them next time. Most people learn by doing. Reading and research is very important, but after all the reading, make sure you attempt to do it. Nothing beats hands-on learning, and patience.

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