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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