Line Structured Light 3D Sensing With Synchronous Color Mapping

A line structured light measurement system is proposed which can obtain both the 3D geometrical and color information of objects. The profile sensor of the system is consisted of a black-and-white camera and an infrared laser line projector. A high precision calibration method is presented for the range sensor by use of a planar target. Then, the point coordinates of the measurement profile can be computed according to center coordinates of laser stripe and the calibrated sensor parameters. The wavelength of the laser projector is 850nm which is out of the spectrum response range of the color camera. Thus, the projected laser line would not affect the color acquisition. The transformation matrix between the two camera coordinate systems is determined and then optimized based on the invariance of cross ratio. By use of the transformation matrix, each point on the profile can be projected onto the image plane of the color camera, and the color information can be obtained synchronously. The measurement results show that the mean radius error of a ceramic ball can reach 0.009mm, and the mean mapping error of profile points on color image plane is 0.16pixel. The 3D measurement results of the textured objects further validate the proposed system.