One of the main problems with using IMD data is that it means using lots of polygons and when you try to load them in google maps they render very slowly and sometime you get a script error in your browser (IE and FF). This is something to do with the way it all works 'under the hood' but I've been trying to investigate ways to make rendering polygons quicker... We'll see. Here's an example I created quickly with google mashup editor for an area in North Liverpool:
http://jrf-googlemaps-test.googlemashups.com/ - see how polygons load slowly
I've been reading and listening and watching online and it seems once you get beyond about 100 polygons everything goes awry. The solution would appear to be image/tile overlays but then this has some limitations that go against what I'm trying to achieve (query clickability, for example). I know people at CASA have used similar approach with their Gmap creator (I've used this and it works very well) and I can understand why but I just wonder if there is another way...Since I'm on the subject of CASA, everyone with an interest in GIS/spatial analysis should go and see MapTube. This is really part of a much wider project about spatial literacy - which I am all for! I've said enough today. Will try a less technical post next time.
