A comparative study on the influence of generalization algorithms on the shape and position of linear features in topographic maps

Map generalization is the Selection and simplified representation of detail appropriate to the scale and/or the purpose of a map. The process involves the use of different operators which runs during one of the Cartographic or modelGeneralization. During the process of digitizing, cartographers face two main problems which are; quality of presenteddata and the file size. Generalization quality assessment is a major issue in contemporary cartography. Besides theevaluation of generalization results, it supports the research for the amount of generalization. Evaluating Generalization algorithms, needs to determine the differences created between the original and th e generalized object. This paper presents a comparative study of two simplification algorithms and their influence on three elements: the firstone is the amount of data volume reduction and the second and third are the elements inherent to linear feature s whichare shape and positional changes of the input line. A number of quantitive measures for the assessment of these changesdue to generalization algorithms are identified. These measures provide a posteriori evaluation of generalizationalternatives, which results from the application of generalization algorithms in different tolarance values . For this reason, after modelling the process of the research and presenting the fundamentals of the theory, in the implementation stage, after the implementation of the two algorithms in different tolerance values, values of eight indicators of quality assessment estimated. The results of evaluation of two algorithms, Lang and Angle , showed that in all measures the Lang algorithm, has a better performance.

Keywords:

Geospatial information system (GIS) , Cartography , Generalization , algorithm , linear feature