Document Type : Research Paper

Author

Master of Geography, University of Tehran

Abstract

One of the main tasks of spatial information systems such as GIS is the aggregation of various data sets and their preparation for communication and analysis in various applications.
 The aggregation of data in spatial information systems requires collection of different types of data drawn from multiple sources, which would in turn necessitate complete alignment among these data sets and the similarity of features and phenomena in them. For example, it is possible that spatial information be extracted in several forms and from several sources, that is, the GIS data sources can be maps from land surveying, photogrammetry and remote sensing on different scales or with different resolution or at different times. In addition, there is a risk of data being obtained in ways that are incompatible and different in terms of validity. Some details may also be omitted or not defined. The incompatibility among various data is likely to come from an incompatibility among spatial information of the data recorded, including differences in dimensions (size), shape, composition, position accuracy or orientation.

1- Abdelmoty,A.I.and El-Geresy,B.A.,1994,An intersection-based formalism for representing orientations in relations a geographic database. In proceedings of the 2nd ACM Workshop on Advances In Geographic Information Systems,(New York: ACM press),PP.44-51.
2- Cui,Z., Chon,A.G. and Randell,D.A., 1993, Qualitative and topological relationships in spatial databases, In Design and Implementation of Large Spatial Databases,SSD 93, LNCS 692,(Berlin: Springer Verlag),pp.396-315.
3- Cohn.A.G., Randell,D.A., Cui,Z. and Bennet,B., 1993,Qualitative spatial reasoning and representation, In Qualitative Reasoning and Decision Technologies, edited by Carrete,P.and Singh,M.G.
4- Egenhofer,M.J.and Sharma,J.,1993,Topological relations between regions in R2 and Z2, In Desing and Implementation of Large Spatial Databases,SSD 93,LNCS 692, (Berlin:Springer Verlag),PP.316-336.
5- Glasgow,J.and Papadias,D.,1992, Computation imagery, Cognitive Science, 16, PP.355-394.
6- Hernandez,D.,1994, Qualitative Representation of Spatial Knowledge, (Berlin:Springer Verlag).
7- Lundell,M.,A qualitative model of physical fieds, In Proceeding of the 14th National conference on Artificial Intelligence,AAAI-92, (Cambridge:AAAI Press,The MIT Press).PP.1016-1021.