Bundle Block Adjustment of Tilt-Shift-Based Multidigital Camera System by Rigorous Orientation Model

Thorough application research of multidigital camera system (MDCS) based on tilt-shift technology has commenced since its prototype system was finished. This letter aims to study mapping applications of tilt-shift-based MDCS with inertial measurement unit and differential global positioning system (IMU/DGPS) data. A rigorous orientation model with equivalent inner orientation elements (IOEs) and digital distortion model (DDM) is proposed to be used in the IMU/DGPS-assisted bundle block adjustment (BBA) for improving geometric accuracy. In this letter, the indoor control field and calibration devices developed by our research team were directly applied to construct equivalent IOEs and DDM of a virtual camera. Two sets of IMU/DGPS-assisted BBA experiments with and without our proposed model and ground control points (GCPs) are presented in this letter, as well as the positioning accuracies. The experimental results illustrate that the positioning accuracies of 53.9 and 46.2 cm in planimetry and height are separately improved to 24.9 and 37.5 with the use of our proposed model in the IMU/DGPS-assisted BBA process at a flight height of 1000 m, ground sample distance of about 20 cm, and no GCP, and the higher accuracies of 19.0 cm in planimetry and 13.6 cm in height are achievable with the help of few GCPs. Therefore, the BBA by the proposed rigorous orientation model is considered practical and feasible for improving mapping accuracies of tilt-shift-based MDCS.