ANALYSIS OF THE ACCURACY OF VECTORIZATION OF ISOLINES ON TOPOGRAPHICAL MAPS OF OSH AND BATKEN REGIONS

Abstract

Relevance.       The modern development of geoinformation technologies and digital cartography has led to an increasing demand for high-precision digital elevation models (DEMs). In mountainous regions such as the Osh and Batken regions of the Kyrgyz Republic, the accuracy of spatial data plays a crucial role in solving tasks related to territorial planning, environmental monitoring, infrastructure design, and natural hazard assessment. One of the most important stages in DEM generation is the vectorization of contour lines from topographic maps, where errors may significantly affect the quality of the final model.

       The article presents criteria for assessing the accuracy of contour line representation on topographic maps of the Osh and Batken regions. For topographic mapping in hard-to-reach and mountainous areas, it is advisable to use navigation measurements and aerial survey data. The methodology for scanning source materials for use in geographic information systems is described. Particular attention is paid to the vectorization and segmentation of contour lines in the GIS “PANORAMA” environment. The results of digitization using the spline method, taking into account the polynomial degree, are graphically demonstrated. It is shown that digital elevation models of mountainous terrain can be generated more efficiently using large-scale maps. Research objective is to evaluate the accuracy of contour line vectorization from topographic maps of the Osh and Batken regions and to identify the main factors affecting the accuracy of the resulting DEMs. Vectorization was carried out using modern GIS software, applying both semi-automatic and manual digitization methods. Accuracy assessment was performed by comparing the obtained data with reference datasets, including SRTM and other digital elevation models. Statistical methods such as root mean square error (RMSE), mean absolute error (MAE), and spatial comparative analysis were used. The results showed that the accuracy of contour line vectorization depends on the map scale, the quality of source materials, the selected digitization method, and the operator’s qualifications. Large-scale maps provide higher accuracy, whereas small-scale maps lead to terrain generalization and increased errors. Optimal results are achieved by combining automated methods with manual verification and correction. The findings of the study can be used to improve GIS-based modeling and support decision-making in land management and engineering design.