Sunday, January 23, 2011

Temporal Imagery Comparison Technique

I was recently made aware (thanks Minfeng) of a cool infographic put together by ABC News in Australia showing a slick interface for comparing two pictures of the same location. You can see the pages here and here. In this case they are using the overlay technique to allow users to evaluate the impact of the Brisbane flooding by comparing aerial imagery taken before and immediately after the flood event.

The imagery comparison technique was so compelling to me that I thought I would see if I could do it in Magik. My scenario was to use imagery available via Web Maps Connector to compare imagery supplied by Bing with imagery supplied by NearMap. What I came up with was a class called a canvas_comparer. It could be used to take two snapshots of the same canvas with different contents and then easily compare the two snapshots dynamically as sliding overlays.

This video demonstrates how it works. I'm wondering if there are other temporal-type applications that this might work for. (I threw this canvas_comparer together in about 1 hour using Graham's very cool Dialog Designer. If you haven't tried the tool yet, you should!!).

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