Active 3d triangulation-based imaging method and device

Abstract

Active 3D triangulation-based imaging comprises steps of: temporally modulating a radiant flux of a lighting unit beam by a binary modulation signal (ms); illuminating a scene (S), which is illuminated by an ambient lighting (AL), by said modulated lighting unit beam (mlub); splitting a ray (ir) imaging a scene point (SP) into two separate imaging rays (ir, ir); said first separate imaging ray (ir) forming an image in a first image sensor (is); temporally modulating a radiant flux of the second separate imaging ray (ir) by the modulation signal (ms) and said modulated second separate imaging ray (ir) forming an image in a second image sensor (is); normalizing a first scene image being an image of all points of the scene (S) formed in the first sensor (is) and a second scene image formed in the second sensor (is); and subtracting the first normalized scene image from the second normalized scene image. The proposed imaging using the random binary modulation signal distinguishes itself by a resistance to intentionally or unintentionally caused interferences. Hence the application is especially advantageous in machine vision appliances provided in an autonomous mobile robot or vehicle. The low radiant flux of the modulated lighting unit beam makes it possible to reduce the input power to a light source of the lighting unit hereby saving the energy and reducing lighting source costs.