Building an accurate range finder with off the shelf components

We present an active triangulation range finding system composed of an independant laser system generating a plane of light projected on an object placed upon a rotary table driven by a personal computer. This computer includes a video digitizer board connected to a camera looking at the scene. Besides its low cost, this system has other advantages over the comparable existing systems. First, we have designed a simple, fast and accurate calibration procedure which does not require any knowledge about the camera parameters or the relative position of the camera with the laser plane. Furthermore, this calibration procedure is performed only once, authorizing stable and accurate results. The result of the scanning of a given object is given in cylindrical coordinates, that is the range image R(0, h) where 0 is the angle of rotation of the rotary table and h the height along its axis of rotation. Choosing different viewpoints, Cartesian range images 2 = j ( X , Y ) of the same object are computed in order to show, with shaded and perspective views of the scanned object, the quality of the results.