Exploitation of photogrammetry measurement system

A digital photogrammetry measurement system (XJTUDP) is developed in this work, based on close range industry. Studies are carried out on key technologies of a photogrammetry measurement system, such as the high accuracy measurement method of a marker point center based on a fitting subpixel edge, coded point design and coded point autodetection, calibration of a digital camera, and automatic image point matching algorithms. The 3-D coordinates of object points are reconstructed using colinear equations, image orientation based on coplanarity equations, direct linear transformation solution, outer polar-line constraints, 3-D reconstruction, and a bundle adjustment solution. Through the use of circular coded points, the newly developed measurement system first locates the positions of the camera automatically. Matching and reconstruction of the uncoded points are resolved using the outer polar-line geometry of multiple positions of the camera. The normal vector of the marker points is used to eliminate the error caused by the thickness of the marker points. XJTUDP and TRITOP systems are tested on the basis of VDI/VDE2634 guidelines, respectively. Results show that their precision is less than 0.1 mm/m. The measurement results of a large-scale waterwheel blade by XJTUDP show that this photogrammetry system can be applied to industrial measurements.