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An experimental evaluation of various approxiate watershed algorithms on triangulated terrains
| Content Provider | Semantic Scholar |
|---|---|
| Author | Koopal, Sonja |
| Copyright Year | 2013 |
| Abstract | Modelling how water flows on landscapes in order to predict floods and other environmental phenomena, has always been of major importance in hydrology and ecological sciences. Today, flow modelling on landscapes is performed in a computer-based environment using digital representations of real-world terrains. One of the most popular digital terrain representations are the so-called Triangulated Irregular Networks (TINs) which are piecewise linear surfaces that consist of triangles. A natural way to model water flow on a surface is to assume that, at any point on the surface, water follows the direction of steepest descent (DSD). However, even this simple flow model has been proven computationally infeasible when applied on TINs. On the other hand, there exist many methods that compute flow paths on TINs approximately, that is without following strictly the DSD on the surface. Such methods do not suffer from the computational problems of the exact flow model. However, flow structures that are produced using these methods may provide a poor approximation of the structures that would be generated by the exact flow model. In this thesis we present various approximate algorithms for computing an important type of flow structure on TINs, namely watersheds. We evaluate these algorithms both in terms of efficiency and approximation quality in comparison to the exact flow model. We consider two different categories of methods; the first category involves methods that use exact arithmetic, and they can introduce new vertices on the TIN with coordinates of possibly large bit-size. The methods of the second category can only perform computations that use floating-point numbers. Among other results, we show that a widely used method provides the least quality of approximation in practice. We introduce methods that present a very good quality of approximation. Furthermore, we show that some methods do well on mountainous terrain whereas others do better on nearly flat terrains. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://alexandria.tue.nl/extra1/afstversl/wsk-i/koopal2013.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
