DETERMINATION OF FIELD CHARACTERISTICS BY THE HELP OF DEFINED FEATURES
Y.S. Sengun, S. Aslan, B. Cetinkaya, O.N. Cobankaya
General Command of Mapping, Cartography, Ankara, Turkiye
In topographic maps elevation related line features are index, intermediate and supplementary contours. Index and intermediate contours are continuous in a map. But not all supplementary contours are drawn on a map, they might be discontinuous.
Production of derived dataset by the help master dataset, index and intermediate contours of derived dataset exist in master dataset by some interval. Therefore these contours can be taken to derived dataset directly. If supplementary contours exist in master dataset, they can be taken directly from it, if not, produced by Digital Elevation Model. Supplementary contour lines are not drawn completely on maps. Only the ones represent specific field characteristics are selected. Supplementary contours are used to represent hills and their correspondence, sudden changes in slope, low slope areas and defiles. These characteristics defined by supplementary contours are not defined features in a dataset. As these characteristics are not present as a feature, the selection of supplementary contours is accomplished by cartographers interactively.
Triangulated Irregular Network (TIN) represents any surface by triangles which are constructed by connecting irregularly dispersed points. By the help of TIN created by index, intermediate and supplementary contours, supplementary contours which constitute a hill and their correspondence are determined automatically. By this way, interactive editing time is shortened, errors made by cartographers are reduced and more accurate maps can be produced.