Accuracy Analysis of Geo-Referencing by Vehicle-Borne Position and Orientation System in Laser Scanning

The main objective of this research is to analyses the accuracy and calibrate the sensors to develop a mobile mapping system for automatic surveying of the 3D objects. This system has become quite popular in recent years due to it´s capability of providing information directly in three dimension. In our system, we have use laser scanners as the main data acquisition device, supplemented by line CCD cameras for texture information and as usual combination of GPS, INS and odometer for position and attitude information. Because every sensor and device has it´s own local coordinate system. For example, GPS output is based on WGS84 coordinates system, Laser data is based on it´s own local coordinate system, the origin of which lies at the laser scanning head and so on for other sensors and device. The major problem is to identify the spatial position of the objects scanned by the laser at any time while the vehicle is moving with reference to a common coordinate system. It involves the integration of all the sensors and devices to a common coordinate system, which is the local mapping coordinate system. The integration process mainly involves the computation of fixed rotation and shift vectors between the INS body and sensors. As the GPS and INS are physically located in two different places, we also need to know the shift vector between the GPS and INS.