My colleagues and I were thrilled with the arrival of Terraserver. Think back with me to 1998. While maps and images for use in GIS on the web today are commonplace, back then it was revolutionary. Suddenly, thanks to an agreement between the USGS and Microsoft, the GIS community had access to USGS topographic maps and aerial photographs down to 1 meter spatial resolution for the entire USA. Two additional features made this service extra special. First, these images were georeferenced, meaning that they could be easily used within a GIS environment. Second, these images were online: No CD-ROMs or other physical media were required! After downloading the maps and aerials for our area of interest, we could read these maps and images into our ArcInfo or ArcView GIS software. True, the header files often needed to be edited first, but this resource gave us a huge leap forward because we had terabytes of data at our fingertips via http://www.terraserver-usa.com, later becoming http://msrmaps.com. Even better was when some enterprising folks at Esri wrote programs to automatically stream these images to ArcGIS.
Now, 14 years later, Terraserver was recently retired. As the National Atlas recently wrote, “We note its passing and salute all those who developed the service. Many people were involved in this groundbreaking effort. […] The National Atlas switched over to services provided by Esri so that Atlas users can continue to link from our maps to large-scale topo maps and aerial views. This takes us full circle. The National Atlas Map Maker was the first on-line, interactive mapper offered by the Federal government. It was partially developed under a joint research effort by the USGS and ESRI in 1997.”
A plethora of base maps, topographic maps, satellite images, and aerial photographs are now available to the GIS user and the general public such as via ArcGIS Online. Times have changed but the need for good base data lives on. While I don’t long for those days of tinkering with header files, I salute the early pioneers who made it all happen. The evolution of GIS data, and discussion about data sources, quality, and related issues are ones Jill Clark and I discuss our book The GIS Guide to Public Domain Data.
I and my colleagues frequently need old aerials for land use change studies, however, and therefore, I wish Terraserver had remained online. Why couldn’t it have done so? What are now the best sources for old aerial photographs?
In Feb 2012 Frank Jacobs wrote an article in the opinion pages of the The New York Times about The First Google Map Wars. The article recalled a day in Nov. 2010 when a Nicaraguan official strayed into neighbouring Costa Rica’s territory. When asked to defend his actions, the official simply replied he wasn’t trespassing according to Google Maps, which did indeed appear to indicate that particular piece of ground belonged to Nicaragua. In an attempt to settle the subsequent dispute, Google agreed to adjust the border.
We reported a similar incident in The GIS Guide to Public Domain Data about a dispute between India and Pakistan over the misrepresentation of the border between Pakistan and the disputed territory of Kashmir. Following threats of action from the Indian Government, Google again agreed to adjust their map of the region and tensions were, for the time being, diffused.
Many of us have become accustomed to using Google, Bing and other on-line mapping resources for many of our quick location-related queries. However, good as they are these resources are not infallible and mistakes do happen. As Jacobs comments, the boundaries depicted by Google Maps remain an unauthorised representation of borders and place names and ‘…popularity does not bestow authority’.