Fig. 2.

Markerless motion tracking algorithm. For a given input sequence of 3-D scans (blue), a template (T₀) is created for the first frame of the scan (S₀) to remove noise along edges and fill holes in the 3-D surface. During surface registration, template surfaces (red) are matched to subsequent input scans using a pairwise nonrigid registration optimization technique. Once optimization is complete, a new template is produced that aligns with the input scan. This process is repeated sequentially through all frames of interest.