Cartometric investigation of the accuracy plan of Lviv in 1894

Ancient maps and plans are important sources of information for multifaceted knowledge of the past. In many studies, the accuracy parameters of spatial data are in demand. The purpose of our work is to study the geometric accuracy of the Lviv plan 1894 by Józef Khovanec. The methodology for studying the accuracy assessment is based on the transformation and geometric analysis of sets of identical points in the ancient plan and the modern reference one. For such a transformation, the Helmert transformation with four parameters and multiquadratic interpolation methods are used. The obtained results make it possible to graphically visualize the inaccuracies of the old plan in the form of displacement vectors, scale and rotation isolines, which clearly territorially diversify the distortions of the cartographic image. Using the method of least squares, a value was obtained that characterizes the positional accuracy of the ancient plan. All calculations and illustrations were made in the MapAnalyst software package, which specializes in the cartometric analysis of old maps. The results of cartometric analysis are influenced by a number of different factors, the decisive ones for the study were the following: the quality of the original; selection of a set of identical items; interpolation technique. When choosing identical points, the main attention is paid to their uniform distribution over the entire area of the plan at a constant position in time. The results obtained represent only one of the possible mathematical models built on the basis of the input data. However, we consider the achieved results to be valid. The processed technique significantly speeds up and simplifies the study of the accuracy of old plans and can be used for similar studies of other cartographic works, and the obtained numerical results and graphic visualizations can be used to compare old plans with each other.