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ŠUMARSKI LIST 5-6/2018 str. 70     <-- 70 -->        PDF

Geometric distortions of historical forestry maps represent the main obstacle in process of map integration with other geospatial data. The effects of the practical applications of various methods for removing the map deformations were investigated thoroughly on the tested sheet of the old forestry map of Bosnia and Herzegovina. Software for the automatic computation of the rectangular coordinates of map grid ticks was developed by authors (figure 2). Significant improvement of transformation quality is achieved by the inclusion of all common points from the map coordinate grid (figure 3) in the base used in transformation (table 1 and figure 5). Regarding the ability to eliminate the nonuniform and unequally distributed distortions in the map content, the analysis of various geometric transformation methods revealed that the best results of the overall accuracy of map transformation were achieved by use of the complex polynomial and locally sensitive models (figures 6 and 7). Relationship between the Accuracyr values and the polynomial degree used, can be modeled by a polynomial function y = 0.502x2 – 5.483x + 22.17 (figure 8). A fifth-order polynomial transformation, based on 81 tie points, results in a 95% accuracy of 1.5 mm · M.
Key words: old forestry map, geometric distortions, common points, coordinate transformations