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Projects – 216,978. Architects – 20,653. Images – 84,293. Institutions - 31. Hits – 42,000 a day. Hits since 2000 – over 11 million. www.philadelphiabuildings.org. All Philadelphia Register Buildings. All PA State Inventory Buildings. All National Register Buildings.
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Projects – 216,978 Architects – 20,653 Images – 84,293 Institutions - 31 Hits – 42,000 a day Hits since 2000 – over 11 million www.philadelphiabuildings.org
All Philadelphia Register Buildings All PA State Inventory Buildings All National Register Buildings All HABS-PABuildings Geographical Coverage All 50 States 57 Countries www.philadelphiabuildings.org
Rae’s Philadelphia Pictorial Directory & Panoramic Advertiser, 1851
Green’s Hotel, from Philadelphia Pa., the Book of its Bourse, 1898, p. 67
New Masonic Hall, Wainwright Lithograph Collection, Library Company of Philadelphia
702 Chestnut Street Archival Tiff Format with Color Control, Caption Information and Scale
Detail of 1858 Hexamer & Locher, illustrating georeferencing with current Philadelphia street centerlines
Centralized Model Athenaeum (PAB) CML, US Census, research projects Arch. Drawings Demo- graphics Central Data and App Server(s) Photos GIS Maps Scanned Maps Athenaeum, Library Company, HSP, Phila. Dept. of Records Phila. Dept. of Records, City Planning, Water Dept. Athenaeum, Free Library
Centralized Model • Data stored in one place • Does not meet local institutional requirements (thus duplicated systems) • Difficult to plan and scale • Difficult to agree on standards: • Metadata • Data refreshing • Access control, use agreements
Centralized Model • Applications run on centralized servers • Faster, but must be controlled in one place
Distributed Model Scanned Maps GIS Maps PACSCL Dept. of Records Photos Land Use Photos Phila. Negro Photo Archives Historical Context PAB CML Applications Data Arch. Drawings Demo- graphics Repositories
Distributed Model • Data stored by each institution (or small group of institutions) • or in a distributed set of centralized systems • Can be built using existing systems, or systems designed for other purposes • Scales by institution • Need to agree on only basic standards: • Metadata (Dublin Core + Geographic Info) • Protocols for data harvesting
Distributed Model • Applications run from anywhere • Applications can be built as needed for particular projects and by different groups • Slower (retrieving data from different sources takes time) • But needed data can be cached (like Google) to provide faster responses
Data Distribution Approaches • Entirely map-based, GIS systems • Open Geospatial Consortium (OGC) Web Map Service (WMS) • Proprietary options (SDEs, ESRI, Google Earth) • Entirely data-based systems • Open Archives Initiative (OAI)Protocol for Metadata Harvesting (PMH) • XML gateways, Z39.50, and the rest
Map-based systems Easier application development Wider compatibility with existing map client software Significant entry barriers (cost/server speed) for providers Data-based systems Application/network provides geocoding Wide support by existing data server software Lower entry barriers for data providers Data Distribution Approaches
The Solution? • Mixed Network Models • Distributed resources, with centralized systems where appropriate • Mixed Data Distribution Approaches • For image-rich base maps (atlas plates, aerial photography, etc.) – WMS • For data-rich collections (historical photos, city directories) – OAI + spatial + temporal.
Challenges • Metadata Standards – Dublin Core? • Geospatial and Temporal Metadata • Map extents, feature points • Date and time, both instant and spanned • Precision, Specificity, and Uncertainty • “702 Chestnut St.” vs. “7th & Chestnut” vs. “Chestnut St.” vs. “Philadelphia” • “1902” vs. “c. 1900” vs. “Early 20th Century”
Challenges (cont’d) • Aggregation / Correlation / Change • Changing place names, boundaries, addresses, and uncertain correlations (city directories) • Re-aggregating data sets (e.g., census data) to provide useful comparisons over time • User Interface • Providing useful interaction both to experience GIS experts, but also to scholars and hobbyists, and even tourists.