Wednesday, May 6, 2009

Historic Topographic Maps of California--San Francisco Bay Area

University of California Berkeley Historic Topographic Maps of California--San Francisco Bay Area

1. Selection Decisions
This project digitized topographic maps of the San Francisco Bay area from 1895 to the present (although the front page says it was last updated in 2007). The front page has a link to "information about this project" that very usefully lays out the selection decisions in an upfront, clear manner. The Berkeley team that did the project used the U.S. Geological Survey's topographic quadrangles of the San Francisco Bay region for digitization because they are in the public domain and were believed to be of most use to the Cal Berkeley community and to offsite users. The project includes 15- and 7.5-minute USGS topographic quadrangles that cover over 100 years of mapping of the region. The maps' coverage includes Point Reyes to Half Moon Bay (North to South) and the Pacific Ocean to Antioch, Livermore and San Jose (West to East). The summary of the selection decisions also includes a few sentences of justification why topographic maps are valuable, useful and worth digitizing in general, and notes that first edition maps were always used when more than one edition was available. As well, the selection decisions paragraph notes that the collection includes some editions of quadrangles published by the Corps of Engineers, the Army Map Service, or the Defense Mapping Agency. In all, "350 maps were carefully selected to represent a historic perspective of the changing landscape of the region from rural to densely urban. "

There are some problems with organization of the project that make nailing down metadata somewhat more difficult than it needs to be. Links to metadata are jumbled up and it is hard to tell what goes with what. However, when specific needed links can be sorted out from the bad formatting, there are useful metadata features, including a pop-up table a lot like our metadata tables in GreenStone, that show the map title, date (when survey was done), alternate date (printed), dimensions, publisher, scale, and notes. However, these appear not to be offered for each and every map. There were many that I viewed where I could not find any metadata at all, but maybe this isn't terribly important to the people that they think will use the maps, in that they know the year from the object title, can reasonably assume that the army or USGS did the survey, and probably just want the information contained in the actual map. It would make any authentication difficult, though. One great feature they have on metadata is a link to the map's MARC record in the Berkeley online library catalog, which would make it very easy to go retrieve the physical copy. There is also more information about the digitization process than I have seen in maybe any other collection I have viewed this semester. The "information about the project" page has two great paragraphs about how the maps were scanned (what equipment was used) and where they did it, what resolution, how they migrated and backed up the data, how the project was funded, how the database was built and by whom, and even how they made the thumbnails. In all, a lot of information. This section also documents one particular librarian's insistence that the images be of very high archival quality, showing compliance with the good practice of "if you're going to digitize, do it as if you will only ever digitize that object once." Contact information for all of the staff responsible for the project is offered at the bottom of the page for people who have questions.

The objects are high quality scanned maps. Links to all of the maps from different years of the same quadrangle are offered on the same page as the particular map you're looking at, so it is quick and easy to do comparison. One downside is that they seem to have gone with some kind of proprietary option for publishing the zoom-view images, through a company called lizardtech. So, the images are all in .sid format, which does not seem to be at all interoperable. I had to download and install a plugin from lizardtech's website to view the zoomable maps. This seems like it could be a big problem if that company disappears and no one can get the plug-in to view the digitized maps in a useable way (ie. not thumbnail sized). There are directions for saving the images in a tiff, gif, or jpg format for later use, though. That said, the images are FANTASTIC. One can zoom in close enough to very clearly pick up stray fibers in the paper or variations in ink thickness in the text on the maps. They are very, very nice, and would probably stand in just fine for the real thing if all you needed was the topographic information they contain.

I would assume this is for people who know a thing or two about topographic maps. I do not, and so the site was a little hard for me to navigate, but for people who know the terminology and the uses, it's probably no problem at all. To me it seems like city planners, geographers, historians, college students, and possibly even high school or middle school students could make great use of these maps.

1 comment:

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