Costa Rica & Openstreetmap

January 8, 2009 in Computers | 3 comments

I got some days ago GPS traces from Costa Rica. I’ve been there and know the roads but at the time I was there I wasn’t interested in Openstreetmap and didn’t have a GPS so I didn’t have any tracks to use to draw roads there until now. This is a short story of what these valuable tracks helped me to do. Sorry for the large images – you have to click to see the full size and quality.

GPS tracks on Google map

All GPS tracks on Google aerial map

Openstreetmap is a community generated map that’s open and free, you can use it as you want with almost no limitations: the same data can be used for a bike, hike or ski piste map and used both for commercial and private use. For more information, see Openstreetmap Wiki. Drawing a map is fun and useful! You record a GPS track, upload it to the server. Draw roads on the GPS track  (or a free map layer – you don’t have to have a GPS!) and tag the roads and points so that they can be generated to be part of the final map. Check the Beginners’ guide for map making.

Before

The capital San Jose and other cities of the Central Valley are quite well covered in Openstreetmap but only very little of other roads. Below you can see the OSM roads in Costa Rica and the province Guanacaste before the new tracks. As you see not much there outside the cities and I tell you, there are more roads than these :)

Costa Rica in Openstreetmap before the new tracks

Northern Costa Rica in Openstreetmap before the new tracks

Tracks

I got two OziExplorer .plt files from two Garmin GPS devices. All together there were 84 saved tracks. Gpsbabel command gpsbabel -i ozi -o gpx inputfile.plt outputfile.gpx converted the files to .gpx tracks with 15606 points of Costa Rican roads and tracks. See the image below.

Process

Viking

I opened the gpx files with Viking to clean, compare to old Openstreetmap data and so on. In the end I found seven longer tracks that were missing from OSM, and exported one gpx file for each of these new roads. The ‘Carratera Interamerican’a highway earlier looked like it was drawn with a ruler and it didn’t have all the curves that are there when you drive it (check the image below and compater the green road and the GPS trace). I also exported all cleaned data to two gpx files that I also uploaded to OSM (see gpx1 and gpx2)

JOSM

Then I opened JOSM and opened all gpx files there. I converted the seven gpx files to OSM tracks, downloaded the OSM data for those areas and edited the new roads to join the roads that already were there. Then I replaced the Interamericana highway with the GPS data with all the curves and also draw some smaller roads mostly from Guanacaste according to the GPS tracks and saved it all to a local OSM file (just in case the upload fails or something like that..). Then I uploaded all the new nodes and roads with JOSM – it took a long time.

The seven new tracks covered 92km (1062 GPS points) of new road and the ‘Carratera Interamericana’ highway track that I used to replace an old route was 69km long (481 GPS points)

I confirmed with Potlatch (the online OSM editor) and informationfreeway (that lets you generate new tiles in minutes instead of waiting until next Thursday for the OSM to be redrawn) that everything looked OK.

GPS tracks on Openstreetmap

All GPS tracks on Openstreetmap

After

It took two days for the OSM cycle to reach the end of the ‘once-in-a-week’ redraw cycle so that I was able to see the results. Click the image below to see an animation of the new roads. It’s not a radical change but still, almost 100km of new busy road and 70km of fixed highway! So just carrying a GPS device with you and recording tracks might make a difference to some others. You can see the current situation behind this link – I’m hoping to get some more tracks from Costa Rica soon to draw more roads.

Guanacaste animation before and after

Guanacaste animation before and after

So now all you have to do is get your GPS and have a look at the Beginner’s Guide. And you don’t even need a GPS device, you can still draw missing roads and buildings with the help of the map layer!

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  1. Harry Wood’s avatar

    Harry Wood on January 8, 2009 at 5:28 pm

    Good stuff. This definately looks like a pretty unmapped area so your contributions are very valuable to OpenStreetMap. Check out the cycle map view of the area which shows contour lines. This gives a feel for the lie of the land in all the blank patches. As for the missing roads, we’ll need your help for that! Guess there’s a lots of rivers in amongst these mountains too.

  2. Risto H. Kurppa’s avatar

    Risto H. Kurppa on January 8, 2009 at 9:20 pm

    Thanks! I’ll see what I can do.. It’d be a lot easier if one could travel there to see, record tracks and update the same day but there are some limitations around, you know :)

  3. Risto H. Kurppa’s avatar

    Risto H. Kurppa on January 10, 2009 at 3:13 pm

    If you have a new enough phone that supports java, has gps/bluetooth and so on, try this: http://www.substanceofcode.com/software/mobile-trail-explorer/ – can be used to record tracks for Openstreetmap and if I read correctly, it’s also able to show the actual Openstreetmap map.