Abstract
Abstract. In recent years, the requirements in the industrial production, e.g., ships or planes, have been increased. In addition to high accuracy requirements with a standard deviation of 1 mm, an efficient 3D object capturing is required. In terms of efficiency, kinematic laser scanning (k-TLS) has been proven its worth in recent years. It can be seen as an alternative to the well established static terrestrial laser scanning (s-TLS). However, current k-TLS based multi-sensor-systems (MSS) are not able to fulfil the high accuracy requirements. Thus, a new k-TLS based MSS and suitable processing algorithms have to be developed. In this contribution a new k-TLS based MSS will be presented. The main focus will lie on the (geo-)referencing process. Due to the high accuracy requirements, a novel procedure of external (geo-)referencing is used here. Hereby, a mobile platform, which is equipped with a profile laser scanner, will be tracked by a laser tracker. Due to the fact that the measurement frequency of the laser scanner is significantly higher than the measurement frequency of the laser tracker a direct point wise (geo-)referencing is not possible. To enable this a Kalman filter model is set up and implemented. In the prediction step each point is shifted according to the determined velocity of the platform. Because of the nonlinear motion of the platform an iterative extended Kalman filter (iEKF) is used here. Furthermore, test measurements of a panel with the k-TLS based MSS and with s-TLS were carried out. To compare the results, the 3D distances with the M3C2-algorithm between the s-TLS 3D point cloud and the k-TLS 3D point cloud are estimated. It can be noted, that the usage of a system model for the (geo-)referencing is essential. The results show that the mentioned high accuracy requirements have been achieved.
Highlights
Terrestrial laser scanning (TLS) is a well established method for an efficient acquisition of 3D point clouds of arbitrary objects
The 3D point clouds are typically captured by means of staticTLS (s-TLS)
To quantify the influence of thereferencing the processing was made without a motion model and by linear interpolation
Summary
Terrestrial laser scanning (TLS) is a well established method for an efficient acquisition of 3D point clouds of arbitrary objects. Examples of recently developed k-TLS based MSS with external (geo-)referencing by a total station are given in (Leica Geosystems AG, 2016) and (Keller, 2016) It can be noted, that both mentioned (geo-)referencing methods are not sufficient enough to reach an total accuracy of ±1mm for the captured point cloud. In case of the external (geo-)referencing an improvement in terms of higher accuracy and faster tracking of the mobile platform can be achieved by using a laser tracker and thereby a more highly accurate determination of the pose with a maximum frequency of 1000 Hz is possible (Hexagon Metrology, 2015). For a high accurate point wise (geo-)referencing the movement of the platform between the laser tracker measurements must be considered This can be realized by a Kalman filter. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume IV-4, 2018 ISPRS TC IV Mid-term Symposium “3D Spatial Information Science – The Engine of Change”, 1–5 October 2018, Delft, The Netherlands of the (geo-)referencing process
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