Abstract:
Digital terrain models are used in wide variety of domains and applications, of which the most important are:
orthorectification of aerial and satellite images, space object modelling, passageways designing, achieving slopes
exhibition maps, hydrological modeling, etc. There are several techniques for data acquisition in order to create digital
terrain models, such as photogrammetry, radargrammetry, interferometry, airborne laser scanning, surveying and
geodetic and cartographic digitization. By using cartographic digitization, digital terrain models are created based on the
digitized contour maps on existing maps, which were brought in digital format by scanning process, this method
involving low costs and being reach of a large number of users. It must therefore assess the vertical accuracy of digital
terrain models created by this method. To achieve results, first were created the digital terrain models based on contour
maps and points of known elevations manually digitized on plans at 1: 1000 scale and maps at 1: 25000 scale, using an
interpolation grid side of 5m and spline bicubic interpolation method. Then, were determined with precision, by GNSS
technology, the coordinates of 18 control points. Based on the grid nodes elevations, using the spline bicubic
interpolation method, were calculated the elevations of the 18 control points and then the differences between them and
those accurately obtained by GNSS technology. By performing a statistical analysis of these differences, the vertical
precision of digital terrain models created from contour maps was determined.
