ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001
5. Applying HOOM Representing the Connectivity of
Multiresolution terrain Model
HOOM stands for Hypergraph-based Objected-oriented Model.
HOOM has many advantages, such as its semantics features,
its visualizing relationship among spatial objects or classes,
and solving the general drawback of HBDS(Hypergraph based
data structure),namely lacking math analyzing methods or
theories. According to research results, we can find that the
K-section can simplify relationships between feature classes or
objects. The representation graph of Hypergraph can help
transforming the viewpoint between the feature object and
feature object relationship. Viz. the feature object relationship
is transformed as a feature object and the feature object as a
kind of relationship.[ Jin ZHANG,2001]
Applying HOOM, we can describe the many terrain feature that
is very difficulty to describe in other model. Such as, terrain
connectivity. Terrain connectivity is very important feature in
DEM applications.
North bank
Fig. 15 Terrain DEM
6. Conclusions and Suggestions
Multiresolution terrain model is a very important research
project and also a very difficulty studying topic in GIS. This
paper overview the situation in this area. For HTIN model,
consistency is key issue in practice applications. So we
introduce the technologyof the tile-to-tile edge matching. In fact,
it is a good idea to solve consistency problem. For
Constructive mutiresolution model based on Delaunay rule, if
we fixed the terrain feature points, the algorithms efficiency
may discount. So we use HOOM represent full terrain
information. For Hierarchical Dynamic Simplification(HDS),
also other key issue exists in applications. That is how to
divide the spatial data. We divide area into tiles. In every tile,
we use quadtree divide tile into next hierarchy, also we use
HOOM establish the feature associations.
The knowledge in the HOOM can be more efficiently to search
for plausible solution loci by finding a subgraph of all the
possible traversable regions. In such a subgraph certain
vertices and edges incident on them, would be excluded such
as “Peak 1”, “Peak 2”, “Cliff 1”,” Cliff 2", “Cliff 3”,” Cliff 4”, “Cliff
5” and “Flat”. A constrained shortest path algorithm can then
be applied to this HOOM to find possible solutios. Fig 16
illustrates the traversable path segments( in solid thock ;ines)
and excludeed graph vertices and edges (in thin dashed lines).
7. Acknowledgement
This paper is funded by Open Research Fund Program of
LIESMARS under grant No.(98)0301 and Nature Science
Fund of Shanxi Province.
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