Dear Dr. Cabell,
perhaps the papers and the information below may clarify the process of motion capture without markers:

- "Combining 3D Flow Fields with Silhouette-based Human Motion Capture for Immersive Video" - pdf file
Christian Theobalt, Joel Carranza, Marcus A. Magnor, Hans-Peter Seidel
MPI Informatik - Saarbrücken, Germany - 2004

- BioMotion Laboratory - Stanford University

- "Capturing and Animating Skin Deformation in Human Motion"
Sang Il Park, Jessica K. Hodgins
School of Computer Science Carnegie Mellon University
The Carnegie Mellon Graphics Lab

commercial systems:
- The Captury

- Dari Motion

- zFlo Motion
Motion Metrix system

I hope this information is useful.
Best Regards,