A comparison study of shaded relief effect
Date Issued
2009
Date
2009
Author(s)
Yang, Su-Ming
Abstract
Shaded relief is a common way to represent terrain relief for allowing readers to identify topography intuitively. Before the development of computer mapping, only very few professional cartographers can perform shaded relief illustration. Thanks for the advancement of computer applications, analytical shaded relief maps are becoming popular using digital elevation model (DEM) and computer mapping packages. Analytical shaded relief usually relies on the calculations of slope and aspect and simulates the shadows of light shinning on the surface. It is based on calculation of terrain analysis in local terrain, and results in great difference with manual shading. Furthermore, the underneath algorithms of various mapping packages are different, so as their results. How to make analytical shading compatible to manual shading is worthy of investigation. The factors affecting analytical shaded relief effect are algorithm (software), landform classification and DEM resolution. This research starts with comparisons of algorithm (software) and landform classification. It is anticipated to find out the characteristics of several available algorithms. MDOW hillshade and Swiss-style hillshade are new algorithms which improves the shortcomings of previous analytical shaded relief methods. The gray value contrast is very strong in four algorithms of Surfer software with rather high standard deviation. Although Lambertian Reflection algorithm has the highest gray value contrast and very detailed relief presentation, it is a good choice to use Lambertian Reflection algorithm if clear and subtle representations of topographical features are desired.
Subjects
landform mapping
shaded relief
map communication
gray value
Swiss-style hillshade
Type
thesis
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