Comparison of an analogue and computer supported line generalisation following the concrete example of the Sitnica River system

摘要

Cartography is a science which most presents changes over ever increasing modern computer technologies. A computer supported generalisation of water flow sets its goal on the effects and achievements of modern cartography science, also showing the results and the levels of basic manual generalisation, comparing them with the effects of a digital computer supported generalisation. Every newly made map which represents the territory given sets the goal of comparing the data, showing the newly created ones in the best and most efficient way. As far as the very river flow is concerned, it is the very degree of generalisation that matters as it affects the quality of the map itself. Generalisation is only one of the methods which can be used for that purpose as the results can be applied to different forms of digital maps. Following the concrete example of the Sitnica River system, using the GeoMedia 6.1 software, by means of GeoMedia 6.1 professional programme, the whole Sitnica River system is presented through vectors on the grounds of topographic maps in proportion of 1:25000, 1:50000, 1:300000. Analyzing the apperance of drainage system of Sitnica, which is shown in both analog and digital, we notice that digital image presents all small meanders as straight lines, in both scales 1:100000 and 1:300000. They are all presented with lines of same thickness and it is impossible to distinguish the importance of watercourse, which river is rich in water or differentiate tributaries from main stream. We will have the results of an analogue and a digital generalisation compared so that only the map which has been properly generalised can be considered to be a map in its real sense.