Camera Calibration And Length Measurement Error Calibration In Digital Close-range Photogrammetry

Digital close-range photogrammetry is an important branch of photogrammetry. It is wide used in the field of industrial measurement for aerospace, auto, shipbuilding. Generally, a quantified result should be given by the photogrammetry system. Then this result must meet with in the tolerance. There are no a unique standard or method to evaluate the accuracy of a photogrammetry system. Though there are a few standards have been established in developed countries, but there is no one in our country. The photogrammetry system was studied. In the same time the evaluation method was studied.According to the different method of image acquisition, digital close-range photogrammetry can be classified into several categories. For clarifying their difference and relation, understanding the feature of photogrammetry and establishing the calibration approach, a digital close-range photogrammetry system was founded. The system consisted of low distortion lens, high resolution CCD camera, high performance workstation,1-D motion guide and high precision rotary etc. can work with different operating model.The distortion of camera will lead to measurement error, so the photogrammetry system has to calibrate the camera. The method based on a plate pattern was selected among all calibration methods. A glass standard was designed and fabricated. The special route was coded to calibrate a single camera and dual-camera system.The measurement error of a photogrammetry can be obtained by measuring a space frame with digital close-range photogrammetry and then calculating the difference between the normal length and the measured length. In order to improve the measurement range and accuracy of space frame, new approach using LaserTRACER was promoted. The principle and composition of multilateration system, the coordinate solving, and the self-calibration of system were given. The two kinds of frames with two materials and two structures were measured by the multilateration system. The preliminary experiments reveal that this approach is feasible.