Terrestrial laser scanners and the investigation of positioning accuracy

By the development of the laser technology and variety of the usage areas by the aspect of many different application areas, a new technological dimension is supplied. With each passing day, for different investigations, this hopeful technology is to become an additional technic for the geodetic applications especially engineering surveys. The 3D terrestrial laser scanner technology which is called as a type of copying technology is to create nearly one to one of the real object from the scanned one and to model it by the help of the point clouds obtained from the scanned object or any surface. This technology is a solution for 3D model generation, using directly data collected by laser scanner however scanned area or object could be complex, unsystematic, big scale or standard type.In laser scanner technology, in the first stage of the process, the object is obtained by the 3 dimensional point cloud data which have density of reflection data in it. Secondly, this process have been completed by selecting point clouds and creating fitting patches of them, fill the blank of points, mesh generation registration, filtering, smoothing, surface triangulation surface wrapping, editing and visualization and digitization. All of 3D modeling process of the laser scanned object has been done by using different software. Finally from generated 3D model surface, area, volume, dimension of object?s information has known.Throughout of this thesis, firstly a literature review and technological aspects of the terrestrial laser scanner is investigated. Then, the surveying procedure of the terrestrial laser scanning, the procesing softwares of the 3 dimensional data, the error sources of this technology and finally the usage areas are cited. Detailed studies about this topics are given.The first case study in this thesis is to apply the scanning procedure for the KOSGEB building in YTÜ, which is scanned 3 sides of the building from two points with colliding the sides. The application is made with the Optech ILRIS 3D and Mensi GS 100 laser scanners. For joining the scanning parts which is scanned in different located points, the automatic registration and manual registration methods are compared in this case study and the detail drawings are made out of point clouds. In the second case study, Pembe Kösk in YTU is scanned within 3 sides. Obtained data from scanning is processed and the 3 dimensional model is formed. In the third case study, the objects which have simple geometric shapes are scanned and 3 dimensional models are formed. The horizontal and vertical sections are taken out of the model. Measured lenghts out of the model are compared with the lenghts which is measured by the stick tool equipment.