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Alexandria Digital Library Project Four Steps to Geospatial Enlightenment Greg Janée Additional text in “Notes” view
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Alexandria Digital Library Project 2 Greg Janée DLESE Developers’ Workshop February 19-20, 2003 Topics o A few things we’ve learned o Issues that affect all three roles producer broker/accumulator consumer o The ADL solutions
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Alexandria Digital Library Project 3 Greg Janée DLESE Developers’ Workshop February 19-20, 2003 Geospatial discovery o Can’t beat word search when it works I want a map of Boulder “Downtown street map of Boulder, Colorado” o But there are so many names for a place... Boulder, Arapahoe County, Colorado Chautauqua, Mapleton Hill, Pearl Street Mall Area code 303, ZIP code 80305, UTM grid 13S Flatirons, Rocky Mountains, Front Range Landers earthquake, hurricane Hugo
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Alexandria Digital Library Project 4 Greg Janée DLESE Developers’ Workshop February 19-20, 2003 If you’re still not convinced... o Remote-sensing imagery is nameless “AVHRR NOAA-13 2002-06-03 14:33 UTC” o Challenge: exactly which two words will find a USGS map of the Flatirons behind Boulder, Colorado? Eldorado Springs
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Alexandria Digital Library Project 5 Greg Janée DLESE Developers’ Workshop February 19-20, 2003 ADL approach o Coordinate-based representation and discovery generic lat/lon coordinates rich geometry –polygons, polylines spatial operators –overlaps, contains o Gazetteer content standard defines representation service maps placenames coordinates client gazetteer library coordinates placenames
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Alexandria Digital Library Project 6 Greg Janée DLESE Developers’ Workshop February 19-20, 2003 Gazetteers: necessary evil o Few (public) sources of gazetteer data o Lousy quality digitized from maps o Difficult problems conflation classification boundary determination change over time o Conclusion gazetteer-based spatial reasoning seems unlikely interaction will likely remain client-centric
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Alexandria Digital Library Project 7 Greg Janée DLESE Developers’ Workshop February 19-20, 2003 Implications of data types o Text is effectively typeless text byte string o Adding geospatial type (i.e., data types) has many implications: input validation internal structures, external representations query language and processing ranking user interface components
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Alexandria Digital Library Project 8 Greg Janée DLESE Developers’ Workshop February 19-20, 2003 ADL approach o Discovery: buckets extensible data type system for metadata –XML representations –search operations explicit metadata mappings foundation for collection-level statistics 9 Dublin Core-like standard buckets o Baby steps: spatial ranking user interface components –map-based result, item viewers –manual georeferencing tool
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Alexandria Digital Library Project 9 Greg Janée DLESE Developers’ Workshop February 19-20, 2003 Scalability o Easy to accumulate lots of data satellites image continuously o Text inverted indexes scale amazingly well o Geospatial R-trees scale... not so well –indexing becomes unwieldy at 10 6 items combining spatial, other constraint types is difficult –efficiently, that is
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Alexandria Digital Library Project 10 Greg Janée DLESE Developers’ Workshop February 19-20, 2003 ADL approach o Distributed library o Federated item-level search over buckets over individual metadata fields mapped to buckets o Centralized collection-level search/ranking over collection statistics –derived from bucket mappings
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Alexandria Digital Library Project 11 Greg Janée DLESE Developers’ Workshop February 19-20, 2003 Textual context o Effective context in text is easy to provide o Consider: poem software
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Alexandria Digital Library Project 12 Greg Janée DLESE Developers’ Workshop February 19-20, 2003 Geospatial context o Does this answer your question? Flatirons 1-5 Flagstaff Rd. Green Mountain
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Alexandria Digital Library Project 13 Greg Janée DLESE Developers’ Workshop February 19-20, 2003 Summary o Searching by placenames is unreliable must use coordinate system gazetteers are a necessary evil o Coordinates introduce the need for data types ease of text vanishes need validation, data type-specific tools o Scalability is a concern easy to accumulate lots of data difficult to combine spatial with other constraint types o Library must provide geospatial context to form queries to evaluate/use item
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