For the past three years this map has run as an old-school MapServer-based application. It worked well for the time, but in the age of slippy-slidy interactive maps, it was showing its age.
The challenge was to somehow leverage our existing foliage infrastructure (yes, we have foliage infrastructure) that is based on collecting foliage reports on a county-by-county basis across New England as the basis for generating a colour-coded map.
The week started with some experimenting with generating county polygons, an effort aided greatly by this helpful PHP script that converts census county boundary files into sets of Google-friendly vertices.
I thought about doing some work to come up with a simplified set of county polygons, but decided to look elsewhere before launching into that.
The idea here, in essence, is that the WMS server becomes an additional “tile making engine” for the Google Map, generating graphic images of the same sort that Google itself generates for the map and satellite layers. Because the hard work is being done server-side, and is bolstered by Google’s pre-fetching algorithms (that fetch neighbouring map tiles before you need them), it all appears quite magical when it’s working.
Moving forward, the ability to drop any WMS layer on a custom Google Map — just look at the variety of WMS layers from Natural Resources Canada, for example — opens up a lot of interesting doors for cool map mashups.
The Interactive Foliage Map is a beta testing right now, and is scheduled to go live next week; you’re welcome to take it for a ride.