|
During the last few years the Center for Sensorsystems (ZESS) develops an image guided 3D measuring system consisting of a 3D laserradar scanner and a CCD camera. The field of application are all kinds of industrial inspection and surveillance tasks where it is necessary to detect, measure and recognize 3D objects in distances up to 10 m with high flexibility. One main problem, which has to be solved during the development phase is the calibration of the single sensors and the multisensor arrangement for such a large working volume. This paper presents a flexible calibration procedure for the 3D multisensor system which makes it possible to determinate separately the outer and inner parameters of the camera and the laserradar scanner. Using the outer parameters which describe the position and orientation of the sensors, it is feasible to integrate the single sensors into a multisensor system. The calibration procedure for the image guided 3D measuring system is based on the method of bundle adjustment. For this we use a 3D arrangement of 3D calibration points which could be detected optimally both by the CCD camera and the laser scanner. It is necessary to known the position of all calibration points. We set store by examining the dependence between the accuracy of the calibration and the expense for providing the calibration normal and the accuracy of detecting the 3D points during the calibration. Beside the use of real sensor data, it is possible to work with data from a system model, which considers the sensors as well as the calibration normal and possible measuring errors. Because of the opportunity to simulate the complete calibration procedure it is practicable to find out an ideal arrangement of calibration points and sensor views as well as estimate the accuracy of the calibration and the steps which lead to a worthwhile improvement of accuracy. This paper gives a survey over the multisensor concept and outlines the mathematical models which are used to describe the single sensors and the complete multisensor system. Further we explain the calibration procedure and the relevant influences in detail.
|
