By Dana Wormer

Bringing historical map data into GIS is breathing new life into centuries-old maps that have long been set aside and overlooked despite the valuable details of history they contain. Through a new interactive GIS Web browser, map and history enthusiasts, along with GIS novices and professionals, can access maps from the 18th, 19th, and 20th centuries and combine them with digital aerial photos, satellite imagery, and other raster-based data. Representing a cross section of the renowned David Rumsey Historical Map Collection, the Internet site (www.davidrumsey.com) features more than 6,500 high-resolution digital images from one of the largest private map collections in the United States.

With a strong interest in history and a curiosity for software tools, Rumsey was first attracted to GIS as he was bringing his initial collection online. Working with MrSID technology from Esri Business Partner LizardTech, Inc., Seattle, Washington, to compress the first 2,300 high-resolution digital images, Rumsey learned about GIS and ArcIMS, and soon partnered with Telemorphic, Inc., Berkeley, California, an Esri Business Partner and ArcIMS developer, to design the new Web browser for his Internet GIS service. The resulting Rumsey Internet GIS mapping service, which is the first of its kind, is the latest step in this map collector's dream to make available his extensive private map collection to as many people as possible.

The new GIS service enables interaction and visualization of historical maps along with digital orthophotos, topographic map sheets, digital elevation models, and satellite imagery from the U.S. Geological Survey. Roads, lakes, parks, and state boundary data sets are also part of the service. Initially launched with maps of California's San Francisco Bay area from the mid-1800s through early 1900s, Rumsey's online GIS service now includes Boston and Washington, D.C., and will soon include New York City, Los Angeles, Chicago, and ultimately, states, and continents.

"When you combine historical maps with modern data, you can visualize the flow of history over several centuries," said Rumsey, president of Cartography Associates, San Francisco. "GIS brings these historical maps into a common, visual language so that we can better understand the context of our history. Integrating geospatial data allows GIS professionals, cartographers, and anyone who loves maps and history to further investigate and visualize historical change."

The collection of 150,000 physical maps is considered one of the largest private collections in the United States. The online collection has been recognized as Yahoo's Pick of the Week; Best of the Net from About.com; Site of the Day from USA Today; Editor's Choice from Netscape, Lycos, America Online (AOL), and other search engines and featured in Wired and Mercator's World magazines and on TechTV. Rumsey also earned a First Prize at the Map Gallery during Esri's 2001 International User Conference for his integration of historical maps and GIS.

The historical maps are scanned with a high-resolution digital camera stabilized to eliminate vibration and designed to capture depth of field, critical for the many three-dimensional objects in the collection. The resulting TIFF files are imported and rectified with ArcGIS and ERDAS IMAGINE software products, compressed using MrSID, then incorporated into the new Internet GIS service.

Building upon their Maplicity Internet GIS and image visualization software, Telemorphic added a new QuadView feature for Rumsey's GIS service, which allows people to display and analyze the old and new map data in four separate views. People of all skill levels can move easily through a series of interactive visualization processes to blend/fade/merge and overlay/swipe multiple image layers, as well as create, save, and print their own custom image products and maps.

"We'll continue to build out each city over time, adding more historical detail such as fire and insurance maps and land parcel/ownership maps that were hand drawn, along with more current satellite imagery, topographic maps, and detailed street information," said Todd Helt, president of Telemorphic, Inc. "Using a Web browser-based application will connect many new people to the capabilities of GIS and image analysis, while helping them gain a better understanding of our history."

Maplicity is a Java 2-based browser that seamlessly integrates with the capabilities of ArcIMS Internet GIS server software. Because the application is built with pure Java, online access is available through a wide variety of industry-standard Web browsers and operating systems (Internet Explorer, Netscape Navigator, and AOL browsers running on Windows, UNIX, Linux, and MacOS X operating systems). Lightspeed Technologies, Inc. (Bakersfield, California), provides the ArcIMS Internet GIS hosting services for the collection.

For more information about the new Internet GIS browser for the David Rumsey Historical Map Collection, please visit www.davidrumsey.com Dana Wormer writes on GIS subjects.