Light stage

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A light stage or light cage is an instrumentation set-up used for reflectance, texture and motion capture often with structured light and a multi-camera setup.

Reflectance capture[edit]

The reflectance field over a human face was first captured in 2000 by Paul Debevec et al. The method they used to find the light that travels under the skin was based on the existing scientific knowledge that light reflecting off the air-to-oil retains its polarization while light that travels under the skin loses its polarization.[1]

BSSRDF: BRDF + Subsurface scattering
BSDF: BRDF + BTDF

Using this information and the simplest, yet most revolutionary to date, light stage was built by Paul Debevec et al. and it consisted of

  1. Moveable digital camera
  2. Moveable simple light source (full rotation with adjustable radius and height)
  3. 2 polarizers set into various angles in front of the light and the camera
  4. A computer with relatively simple programs doing relatively simple tasks.

[1] The setup enabled the team to find the subsurface scattering component of the BSDF over the human face which was required for fully virtual cinematography with ultra-photorealistic digital look-alikes like seen in the Matrix Reloaded and Matrix Revolutions and numerous other movies since the early 2000s.

Following great scientific success Debevec et al. constructed a further 5 newer more elaborate versions of the light stage at the University of Southern California Institute for Creative Technologies and Ghosh et al. built the USC light stage X, the seventh version.

See[edit]

References[edit]

  1. ^ a b "Debevec", "Paul"; "Tim Hawkins, Chris Tchou, Haarm-Pieter Duiker, Westley Sarokin, Mark Sagar" (2000). ["http://dl.acm.org/citation.cfm?id=344855" "Acquiring the reflectance field of a human face"]. ACM. doi:10.1145/344779.344855. Retrieved 2013-07-21. 
  2. ^ Paul Debevec animates a photo-real digital face - Digital Emily 2008
  3. ^ Debevec, Paul (2013). "Digital Ira - A real-time animatable face demonstration". His web site. University of Southern California. Retrieved August 10, 2013.