Computer - Assisted HILL - Shadding Generation from DEM for cartographic enhancement on thematic maps
Raiadika Mastra
National mapping of Indonesia
Hiroaki Kakihchi,Shunji Murai
Institute of Industrial Science
University of Tokyo, japan.
Abstract
There is no doubt that a good eartographic presentation on a map enhances the readability of the map itself. The benefits from the user of the computer as a tool for such enhancement is considerable. Especially in countries where the labor cost is high. Up till recently, the technique widely used to produce hill - shading presentation on a map has been hand drawing or air-brushing.
In this paper, the use of the computer to generate the hill-shading image from DEM data bank is introduced. Results show that this maps and other small scale maps. At the same time it. Can reduce drawing time and other cartographic works.
Introduction
Automation in cartography is not only involves a technical technological and scientific aspect. It also presents human aspects, which are essential to ensure its success and its transition from an experimental stage to an operational one. Also, automated cartography emphasizes the role to eartographers as designers.
Many parts of the cartographer's works can be automated. Hut discussions in this paper emphasizes more the creating of shading effect for the small scale maps or other thematic maps.
The 3-D effect on a map is very helpful to readers who have difficulties in sceing the general view of terrain. As for ordinary users, atlases, thematic maps and even to their Topographic maps. The most famous country to apply the hill-shading effect to their maps is the swiss. Most of cartographers will agree that the Swiss maps are one of the finest cartographic works in the world. Many countries which are applying this technique are still depending on their skilled cartographers who are trained to use air brushing or hand-drawing. To produces the hill - shading effect on one map sheet needs a lot of time. Patience and highly skilled cartographers. However, these can be replaced by using he computer as a tool to generate hill - shading image.
Result shows it is applicable to use this shading image to apply on maps and furthermore overlayed on other features to make a complete themachic map. Tesult shows it is applying layer-slicing with special assigned colours on each layers, the topography of the map itself will appear nicer and also will give a stronger effect.
The use of Hue ( r, g, b), Saturation and Intensity (HIS) instead ofR.G>B. colours only, for producing choropleth image and the combination of shade image with HIS to produce colored image for final use and CRT display is introduced. To give a general view, a brief example of costing aspects for producing this image is also discussed.
