Integrated multi-sensor systems, with their major progress in terms of sensor resolution, data rate and operational flexibility, have become a very attractive mapping tool over the last decade. In the aerial mapping application, for example, exterior orientation parameters (EO) of the imaging sensors are required. Using the measurements from a Differential Global Positioning System (DGPS) integrated with an Inertial Measurement Unit (IMU), the direct determination of the EO parameters can be obtained. This process is referred to as Direct Georeferencing (DG). On the other hand, conventional Aerial Triangulation (AT) uses a block of images with well distributed and sufficient number of Ground Control Points (GCP) for estimating the EO parameters. The DG provides substantial benefits over AT, which include the ability to map remote and inaccessible areas and significantly reducing the cost of the overall project, especially for corridor mapping, or orthophoto generation using existing Digital Elevation Models (DEM). However, the accuracy achieved when using DG is limited by the accuracy achievable by DGPS, IMU and any remaining residual camera/boresight/datum calibration errors. (Abstract shortened by UMI.)
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