Optically lightweight tracking of objects around a corner

TL;DR

This paper introduces a real-time method for tracking objects around corners using standard cameras and laser pointers, employing an analysis-by-synthesis approach to simulate light transport and determine object parameters.

Contribution

It presents a novel real-time tracking technique that does not require specialized ultrafast detectors or narrowband light sources, unlike prior methods.

Findings

Capable of tracking unknown object translation in real time

Able to track known object translation and orientation in real time

Uses standard 2D camera and laser pointer for indirect object observation

Abstract

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.