SPIE Proceedings, Videometrics II, September 7-10, 1993., Boston, Massachusetts, USA
This paper presents a calibration procedure adapted to a range camera intended for space applications. The range camera, which is based upon an auto-synchronized triangulation scheme, can measure objects from about 0.5 m to 100 m. The field of view is 30 degrees by 30 degrees. Objects situated at distances beyond 10 m can be measured with the help of cooperative targets. Such a large volume of measurement presents significant challenges to a precise calibration. A two-step methodology is proposed. In the first step, the close-range volume (from 0.5 m to 1.5 m) is calibrated using an array of targets positioned at known locations in the field of view of the range camera. A large number of targets are evenly spaced in that field of view because this is the region of highest precision. In the second step, several targets are positioned at distances greater than 1.5 m with the help of an accurate theodolite and electronic distance measuring device. This second step will not be discussed fully here. The internal and external parameters of a model of the range camera are extracted with an iterative nonlinear simultaneous least-squares adjustment method. Experimental results obtained for a close-range calibration suggest a precision along the x, y and z axes of 0.2 mm, 0.2 mm, and 0.25 mm, respectively, and a bias of less than 0.1 mm in all directions.