Just thought I’d share a cool looking old map overlay I found digging through the BC Map Services. I enjoy the very detailed, yet simple look. I’ve also superimposed the City of Prince George Flood Plain 1997 layer, which I think is the digitized version of the scanned BC map. Kinda scary to see how far up Patricia/Winnipeg/17th/Massey it would flood, but I guess the City’s got it figured out.
If you’ve used WMS, you’re probably familiar with GetCapabilities (retrieves metadata) and GetMap (retrieves map tiles) requests. GetFeatureInfo is another type of request which retrieves attribute information at a given location, provided the server (e.g. GeoMet) has been configured to provide this information (look for “queryable=’1′ ” in the layer metadata).
One stumbling block I encountered (and likely handled poorly) was overcoming the issue of cross-origin resource sharing (CORS). No matter what I tried, I was blocked from retrieving the request response because, of course, my webpage resides on a different server than the WMS. I got around this by calling a PHP script that copies the text response from the request locally and reads that version. Honestly, I’m not sure why that works and reading the original request doesn’t, but it does and that’s good enough for me. If you have a simpler solution (I’m sure it’s out there), I’d love to learn about it!
Here‘s a super-quick map of Canadian grain elevators, using the Government of Canada’s Grain Elevators of Canada WMS.
The City of Prince George recently unveiled the new City Open Data website, providing access to an impressive selection of spatial (and some non-spatial) datasets. Although these datasets have been available for some time on the old open data catalog, they are all now also available as GeoJSON, GeoService, and OGC WMS.
Here‘s an example of how you can load a Prince George GeoJSON layer through the Google Maps API.
Here’s a map I’ve been picking away at for a little while – the distribution of G20 countries who accused and condemned the Syrian government for chemical weapons attacks against civilians.