Highgroove Hack Night: KML Heatmaps

Every month, Highgroove hosts a hack night where we order food, stock up on beer, and invite anyone and everyone to come hang out in our office to work on cool projects. Last night was a pretty busy one with a handful of open-source gems getting updated, and between helping out other people and building Space Cthulhu I played with turning GPS traces of bike rides into a heatmap.

First up was getting coordinate data for the heatmap out of Google Earth. I put together a quick script using nokogiri and ruby to grab the coordinates from a kml file and output them to CSV:

This gets run like:

ruby mykml2csv.rb > coords.csv

Then, I used heatmap.py in python to generate both an image and a KML overlay:

This gets run like:

python csv2map.py

For my 2007 kml this was only ~3000 points and worked pretty quickly, but for 2008 there are ~60k points and I had to shrink dot size and bump up output size pretty significantly to get it to finish. csv2map.py ran for ~12 hours and finally outputted a pretty neat image:

Looks like I rode to Stone Mountain a lot in 2008. This could probably be generated in a few seconds with a more performant heatmap library, so perhaps I’ll hack one of those together in the future. That said, this was a fun proof of concept and may be useful for people with smaller KML files than me! My entire my.kml has over 1 Million points, so it may never build a heatmap of all of them.

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