UCT CS Research Document Archive

Simplifying Character Skins with Analytic Error Metrics

Merry, Bruce, Patrick Marais and James Gain (2010) Simplifying Character Skins with Analytic Error Metrics. Computer Graphics Forum 29(1):13-24.

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Abstract

Traditionally, levels of detail (LOD) for animated characters are computed from a single pose. Later techniques refined this approach by considering a set of sample poses and evaluating a more representative error metric. A recent approach to the character animation problem, animation space, (AS) provides a framework for measuring error analytically. The work presented here uses the animation-space framework to derive two new techniques to improve the quality of LOD approximations.
First, we use an animation-space distance metric within a progressive mesh-based LOD scheme, giving results that are reasonable across a range of poses, without requiring that the pose space be sampled. Second, we simplify individual vertices by reducing the number of bones that influence them, using a constrained least-squares optimization. This influence simplification is combined with the progressive mesh to form a single stream of simplifications. Influence simplification reduces the geometric error by up to an order of magnitude, and allows models to be simplified further than is possible with only a progressive mesh. Quantitative (geometric error metrics) and qualititative (user perceptual) experiments confirm that these new extensions provide significant improvements in quality over traditional, na¨ıve simplification; and while there is naturally some impact on the speed of the off-line simplification process, it is not prohibitive.

EPrint Type:Journal (Paginated)
Keywords:character animation
simplification
Subjects:I Computing Methodologies: I.3 COMPUTER GRAPHICS
ID Code:642
Deposited By:Marais, Patrick
Deposited On:29 November 2010