英文摘要 |
LiDAR Mapping System (LMS) integrates precise integrated positioning and orientation system, LiDAR, with high flexibility, which can fill the gap in aerial data acquisition and speed up the spatial data acquisition process. National Land Surveying and Mapping Center (NLSC) completed the construction of LiDAR Mapping System (LMS) in 106 and 107, hoping to update the map rapidly and provide timely and correct basic map for the promotion of national economic construction policy planning and the field of disaster prevention. In order to improve the quality of the results of the LMS, this research focuses on the issue of LMS calibration. The information about each kinds of mobile mapping system in our country has been reviewed, and the references that discussing about the calibration methods are also be collected. A calibration procedure for LMS is proposed in this research. The sensors contain positioning and orientation system and LiDAR. This research focuses on the issue of boresight and lever arm calibration. According to the principle of calibration field selection, the transmittance of the calibration field should be more than 50 degrees, which is suitable for GNSS reception and can reduce the effect of GNSS signal blocking and multipath effect. A good calibration field is an open space with hard surface ground and without disturbing objects such as cars or trees. At least on one large building without many detailed structures is recommended in the field. The calibration route includes two drive paths in opposite direction parallel to the vertical surface, two drive paths in opposite direction perpendicular to the vertical surface, and two diagonal drive paths towards or away from the vertical surface. TerraMatch program is suggested for the boresight and lever arm calibration procedure. NLSC LiDAR Mapping System and RIEGL LiDAR Mapping System are calibrated in the pilot region, the outdoor calibration field located in NCKU Kuei-Jen campus in Tainan. LMS with proposed calibration procedure can get the boresight angle and lever arm results successfully. The preliminary results about point clouds of positioning accuracy in direct georeferencing mode show that the 2D precisions of NLSC and RIEGL LiDAR Mapping System are 0.141 and 0.044 meters respectly, and 3D precisions are 0.204 and 0.073 meters. The relevant results can be applied to land use surveys and map updates of Taiwan Electronic Map. |