Multi-station Network Adjustment of Terrestrial LiDAR Data with GPS Positioning

Abstract

Terrestrial LiDAR is the state of the art technology of collecting 3D spatial data Point clouds delivered by a terrestrial LiDAR are referenced to a local coordinate system defined by the laser scanner For most applications raw point clouds should be transformed into a global coordinate system i e geo-referencing of point clouds to match the need for practical applications The geo-referencing of terrestrial LiDAR data is currently relied on known control points However the acquisition of control points for geo-referencing is often troublesome and laborious since the field surveying is usually required for obtaining very high accuracy control points A direct geo-referencing system which is necessarily employed in a mobile LiDAR system is certainly too expensive to the use of a terrestrial LiDAR However it is quite common for a modern terrestrial LIDAR to have a mount for GPS antenna It means that the precise position of a scan station can be obtained in the field Under this circumstance geo-referencing of terrestrial LiDAR data can be achieved by combining several (at least three) overlapping point clouds scanned from multiple stations This is the idea motivates this study This paper presents a methodology to achieve geo-referencing with few or even no control points In our strategy we utilize the observation equations based on the geometric relationship between the center of GPS antenna terrestrial LiDAR and point features to perform multi-station adjustment For the experiments there are two test field involved one is a well-controlled test field in the Tzu-Chiang Campus of National Cheng Kung University and the other case is Eternal Golden Castle in Tainan city The test data of these two cases were processed with the manufacture software and the proposed network adjustment model In the Tzu-Chiang Campus case we tested three conditions of network adjustment which are adjustment with control points only with GPS positions only and with both of them The results show that the accuracy of check points in network adjustment with GPS observations only can achieve about 2 centimeters in E and N directions and about 7 centimeters in H direction In the Eternal Golden Castle case where the landscape is much more complicated The accuracy of check points in network adjustment with GPS observations only can achieve about 4 centimeters in E and N directions and about 7 centimeters in H direction The results show that the accuracy of network adjustment with GPS observations only are quite well enough for applications

Date of Award	2014 Aug 16
Original language	English
Supervisor	Yi-Hsing Tseng (Supervisor)