40 
An Object-Oriented Approach for Handling U.S. Defense Mapping Agency 
Vector Product Format Databases 
M. J. Chung, M. A. Cobb, K. B. Shaw 
Naval Research Laboratory, Code 7441 
Stennis Space Center, MS 39529-5004 U. S. A. 
(chung, cobb, shaw} @nrlssc.navy.mil 
D. K. Arctur* 
Laser-Scan, Inc. 
45635 Willow Pond Plaza 
Sterling, VA 20164-4457 
U. S. A. 
arctur@acm.org 
ABSTRACT 
This paper presents an object-oriented approach for handling Vector Product 
Format (VPF) mapping databases as produced by the U.S. Defense Mapping Agency. 
This approach is implemented in the Object Vector Format Product (OVPF) Smalltalk 
prototype developed by the U.S. Naval Research Laboratory and the University of Florida. 
OVPF provides an integrated framework for VPF products, including capabilities for 
adding and deleting features, modifying feature locations, and exporting to VPF format 
from the internal object representation. Additionally, “winged-edge” topology as given in 
the VPF specification is fully maintained upon feature updates. 
The use of the relational database model for large geographic databases has 
significant manageability and performance drawbacks due to the use of many tables and 
table joins. The VPF family of geographic databases has not escaped these problems. One 
area that has been critically affected by these issues is that of updating. DMA needs to be 
able to update information on existing databases. However, updating of information in 
relational tables is a very complicated process, especially considering the issue of 
referential integrity. This paper will address the OVPF implementation and some benefits 
of using object-oriented technology for modeling complex objects, such as VPF data. 
1. INTRODUCTION 
The use of the relational database model for large geographic databases has 
significant manageability and performance drawbacks due to the use of many tables and 
complex table joins. The Vector Product Format (VPF) family of geographic databases 
produced by the U. S. Defense Mapping Agency (DMA 1993) has not escaped these 
problems. One area that has been critically affected by these issues is that of updating. 
DMA needs to be able to update information on existing databases. However, updating of 
information in relational VPF tables is a very complicated process, especially considering 
the issue of referential integrity. At this time, there is no simple way to handle feature 
updates in VPF products using the relational approach. 
With the emergence of object-oriented technology, these concerns can be addressed 
since the data is represented and stored in a much more maintainable and manageable 
fashion. A prototype application with an object-oriented representation of VPF(OVPF) 
' During the course of this work. David Arctur was with University of Florida at Gainesville. 
Florida. 
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