Lichti, Derek D.Glennie, Craig L.Al-Durgham, KaleelJahraus, AdamSteward, Jeremy2019-06-262019-06-262019-08Lichti, D. D., Glennie, C. L., Al-Durgham, K., Jahraus, A., & Steward, J. (2019). Explanation for the seam line discontinuity in terrestrial laser scanner point clouds. ISPRS Journal of Photogrammetry and Remote Sensing, 154, 59-69. doi:10.1016/j.isprsjprs.2019.05.0120924-2716http://hdl.handle.net/1880/11053010.11575/PRISM/46021The so‐called seam line discontinuity is a phenomenon that can be observed in point clouds captured with some panoramic terrestrial laser scanners. It is an angular discontinuity that is most apparent where the lower limit of the instrument’s angular field‐of‐view intersects the ground. It appears as step discontinuities at the start (0° horizontal direction) and end (180°) of scanning. To the authors’ best knowledge, its cause and its impact, if any, on point cloud accuracy have not yet been reported. This paper presents the results of a rigorous investigation into several hypothesized causes of this phenomenon: differences between the lower and upper elevation angle scanning limits; the presence of a vertical circle index error; and changes in levelling during scanning. New models for the angular observations have been developed and simulations were performed to independently study the impact of each hypothesized cause and to guide the analyses of real datasets. In order to scrutinize each of the hypothesized causes, experiments were conducted with seven real datasets captured with six different instruments: one hybrid‐architecture scanner and five panoramic scanners, one of which was also operated as a hybrid instrument. This study concludes that the difference between the elevation angle scanning limits is the source of the seam line discontinuity phenomenon. Accuracy assessment experiments over real data captured in an indoor test facility demonstrate that the seam line discontinuity has no metric impact on the point clouds.Unless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.journal articleRGPIN-2018-03775https://doi.org/10.1016/j.isprsjprs.2019.05.012