Optically lightweight tracking of objects around a corner
This enables non-line-of-sight tracking for applications like surveillance or rescue, but it is incremental as it builds on prior indirect imaging methods.
The paper tackled the problem of tracking objects hidden around corners by using indirect diffuse light reflections, achieving real-time tracking of unknown object translation and known object translation and orientation with a standard 2D camera and laser pointer.
The observation of objects located in inaccessible regions is a recurring challenge in a wide variety of important applications. Recent work has shown that indirect diffuse light reflections can be used to reconstruct objects and two-dimensional (2D) patterns around a corner. However, these prior methods always require some specialized setup involving either ultrafast detectors or narrowband light sources. Here we show that occluded objects can be tracked in real time using a standard 2D camera and a laser pointer. Unlike previous methods based on the backprojection approach, we formulate the problem in an analysis-by-synthesis sense. By repeatedly simulating light transport through the scene, we determine the set of object parameters that most closely fits the measured intensity distribution. We experimentally demonstrate that this approach is capable of following the translation of unknown objects, and translation and orientation of a known object, in real time.