Interference Model of Two Time-Of-Flight Cameras

The last decade bore witness to increased development of time-of-flight (ToF) camera hardware, algorithms, and applications, particularly 3-D measurement in the fields of human-robot collaboration. Their advantage is in faster digital 3-D image target representation from efficient signal computations. ToF cameras emit modulated light, measuring the round-trip time from its illumination source to its sensor, deriving a distance image. A disadvantage of using multiple ToF cameras is light interference with other cameras’ 3-D measurements. Commonly, adopting an access protocol called frequency division multiple access (FDMA) minimizes interference-related errors but does not eliminate them. The quantification of this distance error has remained a challenging research problem. This paper presents an interference model for two time-of-flight cameras, quantitative analysis, and mathematical modeling to determine the interference-related distance error when using FDMA.