ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci., II-5/W2, 139-144, 2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
16 Oct 2013
High precision target center determination from a point cloud
K. Kregar, D. Grigillo, and D. Kogoj Department of Geodesy, Faculty of Civil and Geodetic engineering, University of Ljubljana, Ljubljana, Slovenija
Keywords: Terrestrial laser scanner, planar target, target detection, point cloud, calibration, registration Abstract. Many applications of terrestrial laser scanners (TLS) require the determination of a specific point from a point cloud. In this paper procedure of high precision planar target center acquisition from point cloud is presented. The process is based on an image matching algorithm but before we can deal with raster image to fit a target on it, we need to properly determine the best fitting plane and project points on it. The main emphasis of this paper is in the precision estimation and propagation through the whole procedure which allows us to obtain precision assessment of final results (target center coordinates). Theoretic precision estimations – obtained through the procedure were rather high so we compared them with the empiric precision estimations obtained as standard deviations of results of 60 independently scanned targets. An χ2-test confirmed that theoretic precisions are overestimated. The problem most probably lies in the overestimated precisions of the plane parameters due to vast redundancy of points. However, empirical precisions also confirmed that the proposed procedure can ensure a submillimeter precision level. The algorithm can automatically detect grossly erroneous results to some extent. It can operate when the incidence angles of a laser beam are as high as 80°, which is desirable property if one is going to use planar targets as tie points in scan registration. The proposed algorithm will also contribute to improve TLS calibration procedures.
Conference paper (PDF, 1156 KB)

Citation: Kregar, K., Grigillo, D., and Kogoj, D.: High precision target center determination from a point cloud, ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci., II-5/W2, 139-144, doi:10.5194/isprsannals-II-5-W2-139-2013, 2013.

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