In the span of the last ten years a major spur of evolution has occurred in the area of obtaining object spatial data. The range and form of spatial data are subject to constant technical evolution, and what comes with that - the possibilities and effectiveness of their computation rise. Terrestrial laser scanning, which is the basis for obtaining 3D data, is also a subject of constant innovation. Currently, manufacturers of terrestrial laser scanners offer a wide range of advanced measurement devices; their precision and efficiency fulfill the need of geodesic monitoring. The scientific research in this article is a comparative analysis of the application of two terrestrial laser scanners used in the measurement of a water dam in Rożnowo. The results of the comparison present the ability to compare the influence of the type of measurement device used on the results of a periodical measurement of water dams. ...