Thu, 17 Mar 2005


I've been doing a lot of work lately on mapping. If you go look at the bicycling category, you'll see some of it. I need to improve the programs that make those maps, but once I'm satisfied with them I'll publish them here. Most generally I want to do GIS-style analysis of maps, only without using a GIS package. The most capable open source GIS package is GRASS, but it has an incredibly steep learning curve. I've tried to learn to use it twice now, and can't get up the slope. It's easier to write my own software than to learn to use GRASS. So that's what I'm doing, and you'll find all of my Python GIS software at pygps.

In particular, today I'm releasing the LatLonUTMconversation library. It converts (predictably enough) between latitude and longitude and UTM coordinates. A GPS receiver will give you lat/lon, but UTM (Universal Transverse Mercator) coordinates are more useful. For one, you can compute distances using them, since each integer UTM tick is one meter. For another, you can locate a point on a map by simple subtraction and division by the scale of the map.

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