A novel laser vision sensor for omnidirectional 3D measurement

Abstract

The combination of omnidirectional imaging and structured-light vision technique provides an efficient solution for omnidirectional 3D measurement. However, the existing omnidirectional structured-light vision sensors are constructed on the basis of curved mirrors, such as parabolic mirrors and conic mirrors, which inevitably generate two obvious problems: first, the difficulty of camera calibration is undoubtedly increased because the camera mathematical model becomes nonlinear and the traditional camera model is no longer applicable in those cases and second, the measurement accuracies of those sensors are far worse than those of traditional structured-light sensors since the captured images are severely warp-deformed. To solve these problems, we developed a novel omnidirectional laser vision sensor by adopting plane mirrors instead of curved mirrors so that the simple traditional camera model can still be used, and more important, the measurement accuracy can be maintained at the same level with the traditional structured-light vision. With respect to the sensor designing, the omnidirectional camera is constructed by a traditional perspective camera and a pyramid reflector, which is made up of four identical plane mirrors of isosceles triangular shape. Moreover, four laser projectors are used to project structured-light to the surrounding scene by the way of splicing. The sensor is calibrated by a 2D planar target and a quasi-3D target. The experimental results show that the relative calibration and measurement errors of the sensor are less than 0.08% and 0.16% respectively. It is proved that complete omnidirectional 3D measurement with high accuracy is feasible with the proposed sensor system.