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  • Always model the simplest control cage possible.
  • Always view your model with smoothing or render it using PxrVisualizer.
    • You can even model in a live PxrVisualizer render !
  • Use creases to make sharp or semi-sharp edges without adding extra edge loops.

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    Creases

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    titleSubdiv Crease demo

    We selected all the edges of an isocahedron and animated their crease value from 0.0 to 5.0.

    All edges can have different crease values and still keep smooth transitions accross the final surface.

  • Corners work like creases for vertices.

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    Corners

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    titleSubdiv Corner demo

    In this animation, 3 edges of a triangular face have a crease value of 5.0.

    We increase the triangle's vertices corner values from 0 to 5.0.


    Note the very smooth transitions around the tightened areas.

  • There are 3 type of subdivision surfaces.
    • Catmull-Clark is the most flexible and popular one.
    • Loop is a triangle-based subdivision surface.
      • No creases or corners
      • useful for cloth simulations
    • Bilinear is like a catmull-clark with infinitely hard creases on all edges

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titleSubdiv vs. Polygon Dicing demo

This is We compare a creased displaced catmull-clark subdivision surface with an equivalent polygon mesh.

Increasing the micropolygon length is equivalent to making the object's size smaller in the image.

  • When the object is large, it is finely tesselated into milions of micropolygons, showing fine displacement detail.
  • When the object becomes smaller than a pixel, only the control base mesh remains.

This Micropolygon Length works a bit like an "automatic level of detail" and preserves memory when an object is so small in screen that it doesn't need an fully detailed representation.

Info

Notice that the subdiv degrades to a much lower number of faces, preserving memory and speeding up raytracing.

This is what we call Data Amplification, when a compact geometric representation can be augmented to create more detail on demand.

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