"Acquiring and Characterizing Plane-to-Ray Indirect Light Transport"
Hiroyuki Kubo, Suren Jayasuriya, Takafumi Iwaguchi, Takuya Funatomi,Yasuhiro Mukaigawa, Srinivasa Narasimhan,
IEEE International Conference on Computational Photography (ICCP) 2018,
May 2018.
Abstract
Separation of light transport into direct and indirect paths has enabled new visualizations of light in everyday
scenes. However, indirect light itself contains a variety of components from subsurface scattering to diffuse and
specular interreflections, all of which contribute to complex visual appearance. In this paper, we present a new
imaging technique that captures and analyzes these components of indirect light via light transport between epipolar
planes of illumination and rays of received light. This plane-to-ray light transport is captured using a rectified
projector-camera system where we vary the offset between projector and camera rows (implemented as synchronization
delay) as well as the exposure of each camera row. The resulting delay-exposure stack of images can capture live
short and long-range indirect light transport, disambiguate subsurface scattering, diffuse and specular
interreflections, and distinguish materials according to their subsurface scattering properties.
An image stack of varying delay on the x-axis and exposure on the y-axis, with values (td, te) in microseconds.
Epipolar images occur when |td| < te/2, and non-epipolar or indirect light otherwise. Notice how the specular
interreflections
of the disco ball move vertically as delay increases in one row corresponding to indirect light paths jumping from
illumination to received plane. The size of the interreflections band is controlled by exposure. All images are
brightened for
visualization.
Author's Preprint