期刊名称：ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
印刷版ISSN：2194-9042
电子版ISSN：2194-9050
出版年度：2007
卷号：XXXVI-5/C55
出版社：Copernicus Publications
摘要：This article describes a very low cost terrestrial Mobile Mapping System (MMS) that was developed at the University of Porto. It incorporates a direct geo-referencing system with a single frequency GPS receiver board and the remote sensors are two progressive CCD colour video cameras with 640x480 resolution. Alternatively the system was used with a direct geo-referencing system previously developed at Porto University based on the integration of data from a dual frequency GPS receiver and an Inertial Measurement Unit. The image acquisition system works independently so it can be used with any direct georeferencing system. The system allows for the association of a position and attitude to each digital frame captured by the video cameras. Furthermore, upon pixel location of objects appearing in the video frames, their absolute geographical coordinates can be extracted. Several calibration steps have to be overcome before the system is prepared to do the survey operations, namely camera calibration, relative orientation between cameras and determination of rotation and coordinate offset between vehicle and cameras reference frames. Procedures were developed in order to guarantee the perfect synchronization between direct geo-referencing data and image data. A software tool was created to allow for an easy object coordinate extraction either in auto mode, where the conjugate coordinates are obtained using image correlation techniques, or in manual mode. Tools for integration with previously existent databases and communication with other GIS platforms were developed as well. Several surveying experiments are described in the paper. The videogrammetry system implemented is a low cost system that can achieve an accuracy in relative positioning of a few decimetres. The overall accuracy depends mainly on the direct georeferencing system used
关键词：Mobile Mapping System; Digital Photogrammetry; Correlation; Camera Calibration
