Three-line Array Stereometry Camera Software System Design

With the application of GIS technology and the demand for digital mapexceeding supply, photogrammetry by satellite has obtained rapid development. Thecore equipment required is a photogrammetric camera when the photogrammetry withthe help of satellite is put into use. At present the advanced photogrammetric cameramainly comprises a film type frame stereo mapping camera and transmission typethree line array stereo mapping camera.Three line array stereo mapping camera is consist of three line CCD cameras.When the three cameras simultaneously sweep to the ground, three images withdifferent visual angle and overlapping are obtained. Each image is obtained by a linearray CCD camera at a certain moment, which corresponds with exterior orientationand interior orientation elements of the camera at imaging moment. According to thephotogrammetry theory, the group coordinate can be solved by the intersectionprinciple when the exterior elements with adjacent time strip image and the imagepoint coordinates are available.Three line array stereo mapping camera spans multiple professional disciplinesin the technical category. The most important disciplines include optics, mechanical,electronics, thermal, software engineering etc... Three line array stereo mappingcamera software systems are located in the top drawer of the three line array stereomapping camera hierarchy, which act as a direct interface between the camera and theuser. The quality of the software system directly affects the user experience and thesuccess or failure of the camera.Four important control algorithms are proposed in this paper, which are neededby three line array stereo mapping camera software systems. The four algorithmsinclude the three line array stereo mapping camera control algorithm, three line arraycamera time synchronization algorithms, three line array camera image motioncompensation algorithms and three line array stereo mapping camera focusing controlalgorithm. The CCD configuration structure of three line array stereo mapping camerathree line array is described in Stereo mapping camera photography control algorithm,the photography baseline of three line array camera and area array camera interval aredefined. Based on the principle of configuration and photogrammetry of three linearray stereo mapping camera, mathematical modeling is carried out and the baselength of photography and area array camera interval are calculated. Three line arraycamera time synchronization algorithms analyze the time synchronization principlesof three line array stereo mapping camera image, design and realize the three linearray stereo mapping camera image time synchronization algorithms, record accurate photography time for three line array stereo mapping camera line array CCD imageand provide necessary conditions for solving the exterior orientation elements of anyline array CCD image and for further calculating all kinds of mappingelements.Three line array stereo mapping camera image motion compensationalgorithm establishes the calculation method of image motion which is based onWGS84coordinate system, devices processing algorithm when the digital elevationmap is in the process of the calculation of image motion and analyzes the influence ofimaging quality caused by the error of image motion. The focusing control algorithmof the three line array stereo mapping camera proposes strategy for the temperaturefocusing and probe focusing and provides concrete process of the realization ofclosed-loop control and open-loop control.In this paper, the external interface of software system of three line array stereomapping camera is designed, including CAN bus interface, GPS second pulseinterface and image data interface. The internal interface of software system of threeline array stereo mapping camera is designed as well, including the RS485interfaceand the interface line cycle. In this paper, the function of four software configurationitems in their respective environment is designed in detail. The implementation of thethree line array stereo mapping camera software system has passed the orbitvalidation, the functionality and performance of the software meet the needs ofphotogrammetry.