Historical Maps Online
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We decided to use the most readily available source of current map data: the United States Geological Survey (USGS). In addition, we faced another technical limitation in not being able to integrate current data with the thousands of maps on the site all at once. As a result, we decided to develop the web GIS on a city-by-city basis, then move on to regional, state, and county levels.
We focused on the San Francisco Bay Area first, obtaining digital orthophotos, topographic map sheets, digital elevation models (DEMs), and satellite imagery from the USGS Bay Area Regional Database.
We quickly learned that just having the data wasn't sufficient. We needed to rectify the digital images of the historical maps to an accurate geographic basemap so that they had common reference frames. This process of "warping" historical maps to modern geographic reference data was challenging. Many historical maps were created before the availability of modern mapping and surveying technologies, and some of the items were tourist maps that were visually surveyed or based on an artist's rendering.
Figure 5. The GIS Quad Viewer showing the same part of San Francisco's Golden Gate Park. Clockwise from lower left: a 1915 map, a modern USGS map, an 1869 map, and a modern aerial photo.
By December 2001, we had completed integration of eleven different maps of the San Francisco Bay Area, from the mid-1800's through early 1900's. Soon thereafter, we added Boston, Massachusetts, Washington, D.C., New York City, and a special Lewis and Clark GIS.
The site has a basic and professional GIS interface intended to allow people of various skill levels to move easily through a series of visualization processes and create, save, and print their own custom maps. Users can also download new image products with complete georeferencing information (world files) for integration into their preferred desktop GIS package.
Adding the GIS feature to the online collection is giving mapping professionals a unique opportunity to learn from the past. Stephen Skartvedt, a GIS specialist for the Golden Gate National Recreation Area, sees many advantages of the new GIS site for his organization. Because Golden Gate Park is now, to a large extent, an island surrounded by development, Skartvedt says the historical maps provide visual confirmation of the value of protected land and show the pace of development in a typical urban setting.
Being able to share historical maps across the web in an interactive environment has proven more rewarding then initially imagined. Response from cartographers, geographers, and GIS professionals has been very enthusiastic.
The latest new dimension to the online GIS experience is three-dimensional viewing and fly-through sequences. Visitors can now fly-through parts of California in the late 1800's such as Yosemite Valley and Los Angeles in 1883, and Lake Tahoe in 1876.
Expansion of the current GIS data sets will continue, adding more cities and more historical detail, such as fire and insurance maps and hand-drawn land parcel/ownership maps, along with more current satellite and aerial imagery, topographic map data, and detailed street information.
We also plan to increase the level of interoperability between the site's Luna Imaging browser and the GIS service, so that users can click on a spatial feature in the GIS view and immediately launch the image browser to see a corresponding map or drawing with more detail.
Figure 6. Images showing the creation of a 3D Map of Yosemite Valley. Clockwise from lower left: a modern digital elevation model (DEM) of the valley, the 1882 Wheeler survey of the valley, a 3D image resulting from combining the DEM and the historic map, and a detail of the 3D historic map.
Soon people will browse multiple map collections at once, comparing maps from widely dispersed institutions in a common internet space. Currently, I am working with several major public map collections interested in achieving this broad goal. One of these joint ventures is with the University of California at Berkeley.
My collaboration with the University of California's East Asian Library has made their collection of rare and fragile historic maps of Japan, some of which date back as far as four centuries, available. More than two hundred maps, including examples of rarely seen woodblock print maps of the ancient city of Edo, modern-day Tokyo, are now available online. Thirteen of the Tokyo maps, dating from 1680 to 1910, were also added to the GIS browser. Additional historic maps of Osaka, Japan, and Kyoto, Japan, have been added to the site as well.
The technology of mapping has changed radically with the advent of computers and the Web. Maps are no longer static items, limited to print-on-paper. Now they are dynamic displays of geospatial and temporal information, assemblies of complex layers of data and image, created by technology-enabled systems. Most significantly, the new maps are embedded into all aspects of our work and play: they are incorporated into office systems and consumer products, working behind the scenes.
Drawing on his personal collection of over 150,000 historical maps as well as his work with geographic information systems, David Rumsey shows how information of all kinds has been mapped and will be mapped in the future.
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I am also working to establish many different ways that the online map collection can be found and accessed by users. We have contributed most of our records to the Open Archive Initiative. Several OAI based search engines are developing, an example being the University of Michigan's OAIster, where our maps can be found along with millions of other documents and images. Our records and images can also be found on popular search engines like Google. We create automatically an individual web page for each of our records, and the Google data "spiders" catalog and index these records. Google currently has over ten thousand record pages from my site. We contribute our data to the ESRI Geography Network, a shared GIS database, and have provided over five thousand georegistered historic maps to the ECAI Meta Data Clearinghouse, a GIS database for historians. With the help of the University of California, my map librarian, Phil Hoehn, is putting all our records with links to the map images into the OCLC catalog, where they can be downloaded and added to library OPACs--UC Berkeley has added over sixty-three hundred of our records to their Pathfinder online catalog, Stanford University has added over fifty-five hundred to their Socrates online catalog, and many other libraries have downloaded and use the records.
I will continue to add new ways for people to find and use our information via the Web. We have recently created a new flash tour of the site in five languages to explain all the site viewers and functions, as well as 360 degree panoramic views of the actual map library space in QuickTime VR. We have also added a TimeViewer to the GIS browser that allows overlaying multiple map layers and then creating an animation that will move through the layers at user-selected speeds.
Figure 7. The TimeViewer, showing six maps of San Francisco from 1861, 1869, 1873, 1890, 1915, and 1995 Digital Orthophoto. The maps blend or swipe from one to the other in sequence.
As the online collection grows in size, it becomes more difficult for users to discover all the content on the site. So, in collaboration with Ideum, I created a Collections Ticker that displays the entire content of the map database, in random or ordered sequence, as a stream of passing thumbnails - dispaying the whole collection in about 8 hours. If someone sees a thumbnail they want to explore further, they can click on it to open it in the Insight viewer. The Collections Ticker provides an alternative to structured searching.
Figure 8. The Collections Ticker, with a stream of thumbnails passing by, provides an alternative to stuctured searching.
In order to allow my historical maps to be searched and combined with other map collections, as well as other cultural and special collections (paintings, photographs, architecture and more), I have launched a portal site called Visual Collections with over 300,000 images from more than 30 collections. All these collections can be viewed individually or combined using the Insight software. This allows historical maps to be seen in a context that enhances our understanding of their meanings and significance. Six map collections in addition to my own are shown, from Stanford University, the East Asian Library at UC Berkeley, Edinburgh University, and the University of South Florida.
Figure 9. The new Visual Collections portal site provide access to over 300,000 images from more than 30 collections of historical maps, paintings, photographs, architecture and more.
Historical maps reveal amazing tales about towns, boundaries, politics, geographic features and early landscape values, and how they changed or vanished with modern development. The very existence of high-resolution map imagery on the Web will bring these beautiful and important materials to the attention of the general public and scholars in ways that have not been possible before. Thanks to the Web and GIS, historians, artists, geographers, cartographers, and others can reconsider their understanding of history.
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