ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS", Bangkok, May 23-25, 2001 
ISPRS, Vol.34, 
24 
out spatial relation represent some constrains among spatial 
relations. Obviously, ordering information is less constraining 
than metric information. It may be less clear though, that 
ordering information yields stronger constraints than topological 
information (Christoph Schieder, 1995). At present the 
formalization description and reasoning model of spatial relation 
lack the integrated consideration of these three kind of spatial 
relations. Combine these three spatial relations together, 
analysis the potential influence among each other, and build an 
integrated description and reasoning model of them, it will 
enhance the uniqueness of spatial description and the accuracy 
of spatial reasoning. The discussion in section 3 and 4 show that 
the integrated description and reasoning of topological, direction 
and distance will bring manful results. 
Direction is an important spatial relation. Because of the different 
need in small-scale space and large-scale space, direction 
relations need to be described at different levels of detail. In this 
paper we propose a three level hierarchical qualitative direction 
description model and present a unified topological 
representation of spatial objects for directions. In different level it 
should build different description and reasoning models, these 
models combine and complement each other. In this way, 
direction relation description is extended. 
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[2] Frank Andrew U. Qualitative spatial reasoning about 
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[3] Frank Andrew U. Qualitative spatial reasoning: cardinal 
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[6] Shekhar Shashi, Liu Xuan and Chawla Sanjay. An Object 
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[8] GOYAL Roop K, and Egenhofer M. J. Consistent Queries 
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[10]Schlieder Christoph. Reasoning about Ordering[A], Andrew 
U. Frank and Werner Kuhn. A Theoretical Basis for GIS 
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341-349. 
THE APPI 
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