CREATION OF A BIM ENVIRONMENT FOR THE HYDRAULIC STRUCTURES OF ŠIRVĖNA LAKE

Abstract

The study was conducted in Biržai district municipality, Biržai town, Astravo Street, on the territory of the hydraulic structures of Širvėna Lake. Photogrammetry and 3D laser scanning measurements were performed to create an accurate digital representation of the hydraulic structures and to analyze the current condition of the hydraulic structures based on the available data. The analytical part of the work was conducted by applying the analysis of available online scientific sources, collecting statistical information, systematic organization of databases, interpretation and modeling of graphical data, summarizing, and utilizing geodetic, photogrammetric, 3D laser scanning technology, and CAD data from real measurements using specialized instruments. The processing was carried out using licensed software packages and methods. A high-quality orthophoto map covering an area of 6,78 ha with a resolution of 5472x3648 and a pixel density of 1.21 cm/pix, along with a point cloud containing 81 million spatial points in the LKS-94 and LAS-07 coordinate systems, was created using photogrammetry technology. Additionally, a topographic plan of the Širvėna Lake dam area at a scale of 1:500 was drawn. Subsequently, an extremely accurate high-quality 3D point cloud consisting of 339.5 million individual spatial points was created by processing data obtained through 3D laser scanning technology with the coordinates of planimetric contour lines. Based on the available 3D point cloud, a 3D model of the Širvėna Lake hydraulic structures was created in the national coordinate system LKS-94 and the height system LAS-07. When comparing point clouds created using different technologies, the root mean square error of the differences in the horizontal position of control spatial points is 0.0006 m, and for the vertical position, it is 0.0721 m. The standard deviation in the XY axis is 0.2489 m, and in the Z axis, it is 0.2686 m.