www.philadelphiabuildings.org

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

Baxter’s Panoramic Business Directory, 1859

Rae’s Philadelphia Pictorial Directory & Panoramic Advertiser, 1851

D.J. Kennedy Watercolor, Historical Society of Pennsylvania, K.1-40.1

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

CentralData and App

Server(s)GIS

Maps

Demo-graphics

Arch.Drawings

Photos

ScannedMaps

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 Networkhttp://www.PhilaGeoHistory.org

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 Networkhttp://www.PhilaGeoHistory.org

Centralized Model

• Applications run on centralized servers

• Faster, but must be controlled in one place

Distributed Model

CML PAB

Dept. ofRecords

PACSCL

Demo-graphics

Arch.Drawings

Photos

ScannedMapsGIS

Maps

LandUse

HistoricalContext

PhotoArchives

Phila.Negro

Photos

Applications

Repositories

Data

Greater Philadelphia GeoHistory Networkhttp://www.PhilaGeoHistory.org

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 Networkhttp://www.PhilaGeoHistory.org

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 Networkhttp://www.PhilaGeoHistory.org

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 Networkhttp://www.PhilaGeoHistory.org

Data Distribution ApproachesMap-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 Networkhttp://www.PhilaGeoHistory.org

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 Networkhttp://www.PhilaGeoHistory.org

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”

Greater Philadelphia GeoHistory Networkhttp://www.PhilaGeoHistory.org

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 Networkhttp://www.PhilaGeoHistory.org