SC 740 Presentation Review

 By Deborah Dent

Professor

University of Southern Mississippi

 October 8, 1997

Dr. Cobb presented a very interesting talk on using an expert system to handle the conflation of vector mapping data. She began the presentation with the definition of map conflation which is regarded as the combination of information from two digital maps to produce a third map which is "better" than either of its components sources. She then pointed out that most of the maps that are available through the National Imagery and Mapping Agency (NIMA) were manually entered and some of the maps date back to the 1800's.

The history of map conflation goes back to the early to mid-1980's and the many of the maps used are those produced and disseminated by NIMA that conform to the Vector Product Format (VPF) standard. This expert system (which used a rule-based approach) takes into consideration issues associated with the problem of matching features and maintaining accuracy requirements.

Dr. Cobb then presented a detailed example using 2 maps of a railroad line as an example. Some of the components needed to produce a single better map include:

• Feature Matching
• Position Alignment
• Feature Deconfliction

Some basic steps needed to achieve the new map include:

• the pre-processing step to unify logical feature parts segment during collection/production
• use of the hierarchical rule base system with matching criteria based on:
• distance measure
• cartographic representation
• FACC feature and attribute codes
• Neighborhood geometry
• Topology

Dr. Cobbs the presented an example of the stages of the user interaction and detailed examples of the matching of features and concluded information concerning potential problems. This appears to be a very interesting subject and research that can be used by both the federal government and private industry.