The article presents the research study of the current state and condition of the geodetic base (polygonometric) network for Kaunas city and region as well as the aspects of its compiling. The geodetic base compiled in the post-war years is considered to be of high quality and is used nowadays. The still existing polygonometric network is seldom studied and thus it remains little known. For the purpose of defining the current state of the geodetic base networks, the search for the points in Karmėlava neighbourhood of Kaunas region has been provided. From the total number of 22 points to be searched, five (i.e. 22 percentage) were determined, but only four points (i.e.18 percentage) were appropriate for measurements. The majority of the points has been destroyed during the construction of the residential buildings or roads, or after the reconstruction works. The measurements have been taken by Trimble R6, by RTK method, 10 times for each point. The most reliable value of the measured geodetic points X and Y were defined as well as the errors of the mean square for one measurement and of the average. The results of the survey (100 respondents) showed that the majority of the professionals apply the points of the polygonometric network when making measurements. However, the problems related to a rather rear usage of the network and the aggravated search of the polygonometric points were encountered. A significant part of the professionals suggested the restoration of the polygonometric network.

In the study, creation of 3D surface relief model in Jelgava, for southern part of the Castle Island is depicted. Information about remote sensing, its historical development, as well as directions of remote sensing, development of photogrammetry and laser scanning is summarized and analysed. Principles of work and methods of photogrammetry and laser scanning are viewed. Information about creation of surface relief model from planning of unmanned aircraft, data capture and alignment to the end product – surface relief model are described. Application of evaluation of data obtained. The purpose of the study – to create 3D surface relief model in Jelgava, for the southern part of the Castle Island. Tasks of the study – to consider development and improvement of photogrammetry and its processes, as well as development of laser scanning and principles of its work; to research, analyse and describe technological processes of laser scanning; to create 3D surface relief model in Jelgava, for the southern part of the Castle Island; to perform comparison of surface models obtained and describe application of laser scanning. Preparation of surface relief model is time-consuming process, which includes flight planning and preparation of end-product. End-products obtained in data processing of laser scanning have very broad usage in many sectors related to geodesy and construction.

Spatial data is constantly evolving, and the accuracy of spatial data is constantly changing. The latest GRPK and orthophotographic map were used in the study. Accuracy is also affected by technological advances, which are driven by improvements in working methods, which include the development of work tools and the development of data sets that contain structured data. The data contained in the data sets are determined by a variety of methods, such as field measurements (GPNS receiver or tacheometer) and analysis of digital photographic images, which are determined using aircraft or satellite systems. The determined data is processed with the help of specialized software, which is selected depending on its functionality and capabilities, and with the help of which the determined data is processed as accurately as possible. Accurate spatial data in densely populated areas makes it easier to carry out planning and design work correctly. The study is performed to determine the accuracy of the coordinates of the selected structures using remote methods. The more similar studies are conducted, the more confident the GRPK data generated remotely will be of the required accuracy, reliability, and applicability to planning, forecasting, and other important tasks. The article compares geodetic measurements and GRPK data and geodetic measurements and ORT10LT data, identifies coordinate differences, the size of the discrepancy and its average, and calculates the root mean square error. The object of the research is spatial and cartographic data of different buildings. The aim of the research is to determine and evaluate the accuracy of the coordinates obtained using remote sensing methods.