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6. CONCLUSION AND FUTURE WORK 
Within the GIS community, emergence of the object-oriented technology is paving 
a new direction. With some advantages of object-oriented technology, some of the 
shortcomings of relational databases may be overcome. OVPF is a sample prototype of 
what object-oriented technolgy can do for VPF databases. Modeling of complex object is 
manageable and maintainable since object pointers are used to reference other objects 
instead of primary and foreign keys as in the relational databases 
Other spatial indexing schemes can be investigated to improve the current 
implementation. Spatial analysis techniques can be incorporated in OVPF based on the 
topological relationships defined by Egenhofer (1989). Complete build and clean processes 
need to be implemented to insure the integrity of topology changes. Also, an use of expert 
or knowledge-based systems can facilitate deconfliction and automation of other 
maintenance and manageabilty concerns. 
7. ACKNOWLEDGMENTS 
We wish to thank the U.S. Defense Mapping Agency and Defense Modeling and 
Simulation Office for supporting this work. 
8. REFERENCES 
D. Arctur, M. Chung, M. Cobb, and K. Shaw, “Comparison and benchmarks for 
import of vector product format (vpf) geographic data from object-oriented and relational 
database files.” In Proc. Fourth Symposium on Spatial Databases, SSD 95, Springer- 
Verlag, pp. 368-384, 1995. 
M. Christiansen, ’’Persistent Object Management using ParcPlace Binary Object 
Streaming Service.” In Smalltalk Report, SIGS Publishing, pp. 4-10, October 1994. 
Chung M., M. Cobb, K. Shaw, D. Arctur, “ An object-oriented approach for 
handling topology in VPF products.” In Proc. GIS/LIS 95, Vol. 1/2, pp. 163-174. 
Cobb M, M. Chung, K. Shaw, D. Arctur, “ A self-adjusting indexing structure for 
spatial data.” In Proc. GIS/LIS 95, Vol. 1/2, pp. 182-192. 
Defense Mapping Agency, Military standard: vector product format Draft 
Document No. MIL-STD-2407, DMA, Fairfax, Virginia, 1993. 
M. J. Egenhofer, Spatial Query Languages, Ph.D. Dissertation, University of 
Maine, Portland, Maine, 210 p, 1985. 
ParcPlace Systems, Inc., VisualWorks Reference Guide, Release 2.0, PPS, 
Sunnyvale, CA, 1994. 
Samet, Hanan, 1995, Spatial databases: tutorial SSD’95, Portland, Maine.