Through our work with YANKEE, The Old Farmer’s Almanac and Elections PEI we’ve had to become adept at understanding the basics of GIS — Geographic Information Systems, or, more generally “maps on computers.” And we’ve had to become adept at finding sources of free GIS data.
The United States is much more enlightened about the public use of government information, and so a lot of U.S. Government generated GIS data is freely available online. Ironically, it’s often possible to get Canadian data for free from the U.S. too. Three excellent starting points are:
- The Map Layers Warehouse of the U.S. National Atlas has a great selection of base layers, running from basics like roads and state lines to magnetic field, zebra mussels infestations and time zones. I’m a particular fan of their Shaded Relief of North America. They make their data available for free download in ESRI Shapefile and SDTS formats.
- The AWIPS Map Database page, from the National Weather Service, is, as you would expect, weather-focused. But they do have some basic layers, like Canadian provincial and territorial boundaries, that aren’t available from the U.S. National Atlas.
- The Canadian GeoBase site is proof that Canada is catching up. In particular I’ve found their National Road Network is a useful resource (although, at least for PEI, it’s currently without street and road names attached; this is coming in a later revision).
Put the data you can get from those three sites together with an open source mapping application like MapServer and you can create powerful mapping applications (like this and this) at no capital cost.
What’s missing from the mix is, alas, an open source GIS editing application — something along the lines of MapInfo or ArcView. There is GRASS, but I have found its complexity so insurmountable as to be almost useless. I’m sure it can be very powerful if you are willing to mount an assault on its learning curve, but that would take the kind of time and dedication I can’t afford.
Even without a GIS app to create new layers, however, you can still, using MapServer and PHP or Perl, programatically create new layers — both points and polygons. Although this isn’t “point and click,” it does make it possible to map your own data on top of others’ base layers.
I’m pretty convinced that things are heating up inside the nexus GIS, GPS, telephony and the web: these tools, and this data, can drive a lot of interesting experimentation in people’s basements.