The GIS Lens
Sanjay Gangal is the President of IBSystems, the parent company of AECCafe.com, MCADCafe, EDACafe.Com, GISCafe.Com, and ShareCG.Com.
Reading Historical Maps Digitally: How Spatial Technologies Can Enable Close, Distant and Dynamic Interpretations.
January 18th, 2012 by Sanjay Gangal
Article source: davidrumsey.com
This is the opening keynote given by David Rumsey at the Digital Humanities 2011 (DH 11) conference on June 19th at the Stanford University.
The David Rumsey Map Collection was started over 25 years ago and contains more than 150,000 maps. The collection focuses on rare 18th and 19th century maps of North and South America, although it also has maps of the World, Asia, Africa, Europe, and Oceania. The collection includes atlases, wall maps, globes, school geographies, pocket maps, books of exploration, maritime charts, and a variety of cartographic materials including pocket, wall, children’s, and manuscript maps. Items range in date from about 1700 to 1950s.
Digitization of the collection began in 1996 and there are now over 27,000 items online, with new additions added regularly. The site is free and open to the public. Here viewers have access not only to high resolution images of maps that are extensively cataloged, but also to a variety of tools that allow to users to compare, analyze, and view items in new and experimental ways.
Maps are uniquely suited to high-resolution scanning because of the large amount of detailed information they contain. In their original form, maps and atlases can be large, delicate, and unwieldy. Digitization increases their accessibility, and when combined with online catalogs, they can be searched in a variety of ways. The site allows public access to rare maps that have been hidden or available only to a few.
With Luna Imaging’s Insight® software, the maps are experienced in a revolutionary way. Multiple maps from different time periods can be viewed side-by-side. Viewers can also create their own collections of maps that hold particular interest by saving groups of images. Complete cataloging data accompany each image, enabling in-depth searches of the collection.
Materials created in America and that illustrate the evolution of the country’s history, culture, and population distinguish the collection. Close inspection of the maps often reveals the growth and decline of towns, mining excavations, the unfolding of the railroads, and the “discovery” of the American West by European explorers. The collection also includes European imprints containing maps of the Americas that were influential to American cartographers, as well as maps of other parts of the world distinguished by great craftsmanship, significance, and beauty.
A more detailed description of the evolution of the physical collection into the online collection can be found in “State of the Art“, an article that originally appeared in Mercator’s World Magazine.
About the technology
The collection on the Internet brings together the finest optical equipment and digital scanners, cutting edge viewing technology, the latest image processing software, powerful wavelet compression, and reliable long-term storage of digital images. The digitized maps are very high resolution images scanned at at least 300 pixels per inch, as measured against the original map’s dimensions. The larger maps generate files frequently approaching two gigabytes in size; the average file size of images in the collection is 200 megabytes.
The following hardware and software is used in the process of creating and distributing the images over the Internet: