Episcan360: Active Epipolar Imaging for Live Omni-directional Stereo

Abstract

Active epipolar imaging simultaneously illuminates and images a scene along epipolar planes. The recent devices based on this principle, such as Episcan [1] and EpiToF [2], significantly reduce the effects of indirect light transport and ambient light, resulting in live capture of high resolution 3D at longer ranges indoors and outdoors. However, these devices are designed for narrow fields of view where lens distortion can be ignored and epipolar plane/line constraints are satisfied. In this work, we extend active epipolar imaging to obtain live-omnidirectional stereo for the first time. Instead of using a 2D sensor/projector, we use a 1D sensor and 1D light sheet source that are placed in a rectified configuration. We observe that when the lens center axis and the sensor are aligned, the distortion is mostly along that axis and epipolar plane constraint remains satisfied. This allows us to use small wide-angle lenses resulting in a compact 1D Episcan. This 1D Episcan is then spun quickly to obtain an near-spherical field of view. Based on this design, we demonstrate a custom-built hand-held working prototype for live capture of omni-directional active stereo images.