Programmable Non-Epipolar Indirect Light Transport: Capture and Analysis

Hiroyuki Kubo, Suren Jayasuriya, Takafumi Iwaguchi, Takuya Funatomi, Yasuhiro Mukaigawa, Srinivasa G. Narasimhan

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


The decomposition of light transport into direct and global components, diffuse and specular interreflections, and subsurface scattering allows for new visualizations of light in everyday scenes. In particular, indirect light contains a myriad of information about the complex appearance of materials useful for computer vision and inverse rendering applications. In this paper, we present a new imaging technique that captures and analyzes components of indirect light via light transport using a synchronized projector-camera system. The rectified system illuminates the scene with epipolar planes corresponding to projector rows, and we vary two key parameters to capture plane-to-ray light transport between projector row and camera pixel: (1) the offset between projector row and camera row in the rolling shutter (implemented as synchronization delay), and (2) the exposure of the camera row. We describe how this synchronized rolling shutter performs illumination multiplexing, and develop a nonlinear optimization algorithm to demultiplex the resulting 3D light transport operator. Using our system, we are able to capture live short and long-range non-epipolar indirect light transport, disambiguate subsurface scattering, diffuse and specular interreflections, and distinguish materials according to their subsurface scattering properties. In particular, we show the utility of indirect imaging for capturing and analyzing the hidden structure of veins in human skin.

Original languageEnglish (US)
Article number8877764
Pages (from-to)2421-2436
Number of pages16
JournalIEEE Transactions on Visualization and Computer Graphics
Issue number4
StatePublished - Apr 1 2021


  • Light transport
  • computational photography
  • indirect light
  • synchronized projector-camera system

ASJC Scopus subject areas

  • Software
  • Signal Processing
  • Computer Vision and Pattern Recognition
  • Computer Graphics and Computer-Aided Design


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