AMCW lidar systems such as the ones used in Microsoft Kinect for Xbox One, Microsoft HoloLens or Google Tango smartphones provide affordable full-field range imaging at high frame rates. They rely on indirect measurements of the time of flight of light. However, the assumption of a single time of flight per pixel is inadequate in reality. Global illumination effects lead to light paths of varying length which interfere and lead to strong, systematic distortions in range images. To handle this problem correctly, a full reconstruction of the time-dependent impulse response of light is needed per pixel. Such images of impulse responses are known as transient images. Reconstructing them from AMCW lidar measurements is a non-trivial inverse problem. We demonstrate that a specific measurement procedure turns this problem into a trigonometric moment problem. These problems are well-studied and powerful closed-form solutions exist. The resulting techniques serve to reconstruct complex impulse responses from measurements at few (e.g. three) modulation frequencies. The approach scales well from interactive capture of range images with reduced multipath interference to capture of high-quality transient images. Good transient images enable a more complete understanding of light-transport in the captured scene. The research further opens up new ways to analyze the reconstruction problem itself. Most of the presented work has been published at SIGGRAPH Asia 2015.
09:30 - 10:00