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After differences are found, a spatial conflation program (to be 
developed) will be used to process all these datasets and generate 
a new, consistent dataset. Spatial conflation is the technology 
that allows us to take two datasets (Di and D») representing 
elements of the same geographic area and generate a new dataset 
(D3), which contains a unique representation of all elements in 
the two datasets. Combination of these two datasets is done 
based on a set of cartographic and geometric rules. Map 
conflation has been in use by the Bureau of the Census of the 
U.S. Department of Commerce for several years and several 
commercial programs are available. In our case, the two datasets 
to be considered are the digital dataset representing the out-of- 
date terrain and the dataset representing the changes on the 
terrain (collected from digital orthophotos, GPSVan™, and other 
sources). This portion of the research has just begun. 
Finally, we have found that automation tools must be developed 
to make the revision process cost-efficient. We are developing 
some of these automation tools on PCs. 
6. CONCLUSION 
Spatial data revision is a field of great importance for GIS. It 
offers many challenging problems that need to be understood and 
solved in a cost-efficient fashion. The Center for Mapping is 
committed to their study and is making major progress in their 
understanding and solution. 
References from Books: 
Bertin, J., 1983, Semiology of Graphics, Madison: The Univer- 
sity of Wisconsin Press, pp. 4-19. 
Thompson, M.M., 1987, Maps for America, U.S. Depart- 
ment of the Interior Geological Survey. 
References from Other Literature: 
Decker, K.M, 1996, Revising Digital Cartographic Products, 
Unpublished technical paper, The Ohio State University 
Department of Geodetic Science and Surveying, p. 7. 
Ramirez, J.R., 1996, Spatial Data Revision: Current Research 
and its Influence in GIS, Proceedings PLANS'96 Symposium. 
Ramirez, J.R., 1995a, Revision of hypsographic data: a 
conceptual framework, Proceedings 1995 Mobile Mapping 
Symposium, The Ohio State University Center for Mapping and 
Department of Geodetic Science and Surveying, pp. 153-162. 
Ramirez, J.R., 1995b, Map revision and new technologies: a 
general framework and two proof of concepts", Proceedings 17th 
International Cartographic Conference, pp. 924-932. 
Ramirez, J.R., 1991, Development of a Cartographic Language, 
Proceedings COSIT'91. 
Ramirez, J.R., 1988, A Map Representation Theory for the 
Evaluation of Digital Exchange Formats, Columbus: The Ohio 
State University, Department of Geodetic Science and Surveying, 
Report No. 389, pp. 32-75. 
683 
Ramirez, J.R. and Fernandez-Falcon, E., 1994, Development of a 
Cartographic Communication Theory for the Transfer of 
Meaningful Information: Feasibility Study, Office of Research-The 
Ohio State University, Seed Grant No. 221551/93. 
Ramirez, J.R and Lee, D., 1991, The Development of A Cartographic 
Model for Consistent and Efficient Map Production, Final Report 
USGS Grant No. 14-08-0002-G1884, The Center For Mapping, The 
Ohio State University. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996