Sunday, August 30, 2015

OpenStreetMap



When skiing or hiking at a new place, suitable maps are essential. These maps can be hard to come by, however, and most GPS maps do not contain information about walking paths, ski slopes or lifts. OpenStreetMap, however, has a lot of good information, and I have been using it in off-piste skiing, finding ski areas, and hiking around the world.

OpenStreetMap is a community-driven project, with contributions from people with local knowledge. My friend Tero is one of the thousands of contributors to OpenStreetMap. His goal is to add information about the out-of-the-way ski areas that we often visit. The existence of the ski area itself can be marked, making finding the place easier. Ski lift positions help general navigation in the area for the purposes of off-piste skiing, etc.

In this article Tero explains how to make contributions to OpenStreetMap. The basic idea is quite easy: mark waypoints or tracks on your GPS and then upload these to the OpenStreetMap website.

For instance, at Los Arenales Tero marked the endpoints of the two ski lifts, and then added the lifts to the database. Here is how Los Arenales looked like (overlaid with our GPS tracks from the climb) before the change:



And then after the change the ski lifts are visible:


Here are the more detailed instructions.

First, you need a GPS device. Tero uses Garmin eTrex devices (such as eTrex 30x) that support OpenStreetMap formats natively. Second, you need to register at openstreetmap.com to be able to submit additions.

While on the mountains or on the hike, keep the GPS on and let it save your track. It may also be useful to mark specific points, such as the beginning or end of a ski lift or trail.

After the the trip, do the following:
  1. Connect your GPS to your computer using a USB cable. Mount the device, if needed on your operating system.

  2. Copy the GPS tracks from the device to your computer. For instance, on a Garmin the tracks are in the Garmin/GPX or Garmin/GPX/Archive directories.

    If necessary, you may need to combine multiple GPX files. There is a handy script for doing this at end of this blog post.

  3. Go to openstreetmap.com, log in, zoom in to correct area, and click edit.

  4. Open map data tab from the right, and click on the magnifying glass next to the "local GPX file" text and select your track. You can only have one track loaded at one time.

    Now you have map and your track overlaid.

  5. Check if there is errors in the existing slopes, lifts, or other features. If there are, fixing those errors is useful. See http://wiki.openstreetmap.org/wiki/Piste_Maps for information what information slopes and lifts should have.

    For example in another ski area we visited in Chile, Araucarias, there are several ski lifts. But only one of them was listed in OpenStreetMap. And even that one had missing information. Make sure the name is correct, or if there is no name, keep the name empty. Make sure the lift direction is correct, i.e. from down to up.

  6. For the lift at Araucarias, Tero changed the type from generic aerialway to Chair Lift, added Occupancy, and marked that it is not heated, and does not have bubble.

  7. To add a lift, select a line, clicking in the bottom of the lift, and then at the top twice (first to mark the point, second time to finish making the line).


  8. Then fill in the information. To use the Araucarias lift as example, first write "T-bar" in the search text, and pick "T-bar lift" from the list. That is it, unless the lift has a name in which case you should add that as well.



  9. To add pistes do the same, i.e. add lines for it. You can normally use multiple clicks, there is no point of trying to make them too accurate, as this is just the approximate center line of the slope. Like lifts, slopes have a direction, from top to bottom.

  10. Once the lines are added, search for Piste, and select "Piste/Ski Train", and then change Type to "Downhill".

    Add name is if the slope is named, and try to be accurate with the spelling. If there is numbers or letters for the lifts, add them as "Ref", by scrolling down on the left, and clicking "+" after the All tags menu, and then writing "ref" on the left side, and writing number/letter on the right.
    The OpenStreetMap entry for Araucarias shows examples of pistes and lifts.

  11. When you have made all your changes, save them by clicking save at the top of the page, and write useful description what have you done.




Other pictures from the environment at Los Arenales:




Appendix A: Script

This handy Perl script is one way of combining GPX files:
#!/usr/local/bin/perl -w
$header=1;
foreach $i (@ARGV) {
   open(FILE, "<$i") || die "Cannot open $i : $!";
   undef $/;
   $file = <FILE>;
   $file =~ s/>/>\n/g;
   ($h, $b, $f) = split(/<\/?trk>\n/, $file);
   if ($header) {
print $h;
print "<trk>\n";
$header = 0;
   }
   print $b;
   close(FILE);
}
print "</trk>\n";
print $f;
Photos and videos (c) 2015 by Jari Arkko and Tero Kivinen. Script and instructions by Tero Kivinen. Tämä blogi löytyy myös suomeksi. This blog is also available as a TGR version.

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