Temporal frequency probing for 5D transient analysis of global light transport

Matthew O'Toole, Felix Heide, Lei Xiao, Matthias B. Hullin, Wolfgang Heidrich, Kiriakos N. Kutulakos

Research output: Contribution to journalConference articlepeer-review

99 Scopus citations


We analyze light propagation in an unknown scene using projectors and cameras that operate at transient timescales. In this new photography regime, the projector emits a spatio-temporal 3D signal and the camera receives a transformed version of it, determined by the set of all light transport paths through the scene and the time delays they induce. The underlying 3D-to-3D transformation encodes scene geometry and global transport in great detail, but individual transport components (e.g., direct reflections, inter-reflections, caustics, etc.) are coupled nontrivially in both space and time. To overcome this complexity, we observe that transient light transport is always separable in the temporal frequency domain. This makes it possible to analyze transient transport one temporal frequency at a time by trivially adapting techniques from conventional projector-to-camera transport. We use this idea in a prototype that offers three never-seen-before abilities: (1) acquiring time-of-flight depth images that are robust to general indirect transport, such as in-terreflections and caustics; (2) distinguishing between direct views of objects and their mirror reflection; and (3) using a photonic mixer device to capture sharp, evolving wavefronts of "light-in-flight".

Original languageEnglish (US)
Article number87
JournalACM Transactions on Graphics
Issue number4
StatePublished - 2014
Externally publishedYes
Event41st International Conference and Exhibition on Computer Graphics and Interactive Techniques, ACM SIGGRAPH 2014 - Vancouver, BC, Canada
Duration: Aug 10 2014Aug 14 2014

All Science Journal Classification (ASJC) codes

  • Computer Graphics and Computer-Aided Design


  • Coded illumination
  • Computational photography
  • Light transport
  • Photonic mixer devices
  • Time-of-flight imaging


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