Reading 21: Coordinates and Cages

by Mike Gleicher on April 21, 2013

(note: this reading is for Monday, April 29th – it might appear out of order)

We learned about “regular” skeletal skinning, but here’s an alternative: using a space deformation (usually controlled by a cage) to deform the rest-skin shape. This is a also called a coordinate approach, since the way the deformation works is by pre-computing a “coordinate” for each point in the space, that gets changed based on the controls.

While I would really like you to read all the technical details of how this works, and the different choices for doing coordinates, I realize that you’re too busy with your projects. So the required reading is pretty light:

If you want to learn more, you can read the actual SIGGRAPH paper:

  1. Joshi, et al. Harmonic Coordinates for Character Articulation SIGGRAPH 2007.
  2. Ju, et al. Reusable skinning templates using cage-based deformations. SIGGRAPH Asia 2008.

But, to be honest, you’ll get the most out of the magazine article above.

You need to answer the question on Moodle (and the AMS article will be sufficient).

Here’s a really nice student project from last time comparing some of the approaches to coordinates:

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