Projects – 216,978 Architects – 20,653 Images – 84,293 Institutions - 31 Hits – 42,000 a day Hits since 2000 – over 11 million

All Philadelphia Register Buildings All PA State Inventory Buildings All National Register Buildings All HABS-PA Buildings Geographical Coverage All 50 States 57 Countries

Baxter’s Panoramic Business Directory, 1859

Rae’s Philadelphia Pictorial Directory & Panoramic Advertiser, 1851

D.J. Kennedy Watercolor, Historical Society of Pennsylvania, K

Green’s Hotel, from Philadelphia Pa., the Book of its Bourse, 1898, p. 67

New Masonic Hall, Wainwright Lithograph Collection, Library Company of Philadelphia

Philadelphia Contributionship fire insurance survey, number 9521

McElroy Directory, 1857

Optical Character Recognition Process

Spreadsheet made from OCR Text

Hexamer & Locher Atlas, 1858, Free Library of Philadelphia

Archival Tiff Format with Color Control, Caption Information and Scale 702 Chestnut Street

Detail of 1858 Hexamer & Locher, illustrating georeferencing with current Philadelphia street centerlines

Centralized Model Central Data and App Server(s) GIS Maps Demo- graphics Arch. Drawings Photos Scanned Maps Phila. Dept. of Records, City Planning, Water Dept. Athenaeum, Library Company, HSP, Phila. Dept. of Records Athenaeum (PAB) Athenaeum, Free Library CML, US Census, research projects

Greater Philadelphia GeoHistory Network 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

Greater Philadelphia GeoHistory Network Centralized Model Applications run on centralized servers Faster, but must be controlled in one place

Distributed Model CML PAB Dept. of Records PACSCL Demo- graphics Arch. Drawings Photos Scanned Maps GIS Maps Land Use Historical Context Photo Archives Phila. Negro Photos Applications Repositories Data

Greater Philadelphia GeoHistory Network 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

Greater Philadelphia GeoHistory Network 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

Greater Philadelphia GeoHistory Network 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

Greater Philadelphia GeoHistory Network Data Distribution Approaches 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

Greater Philadelphia GeoHistory Network 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.

Greater Philadelphia GeoHistory Network 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. “7 th & Chestnut” vs. “Chestnut St.” vs. “Philadelphia” –“1902” vs. “c. 1900” vs. “Early 20 th Century”

Greater Philadelphia GeoHistory Network 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.

Greater Philadelphia GeoHistory Network