Using OpenStreetMap mapping for geocaching

OpenStreetMap is a free map of the world. It is created by volunteers who trace highways, byways and points of interest with a GPS, then use these raw data points to build a high quality map of the entire planet. Like Wikipedia, anyway can become an editor. But perhaps the crucial point is that anyone is free to use the data under a Creative Commons by-sa-2.0 licence.

While you can view the current state of the map at www.openstreetmap.org, there are other renderings of the data tailored for specific uses. For example, Freemap is aimed at walkers, while OpenCycleMap is tailored for cyclists.

It is this freedom which fosters innovation, and I think it’s an exciting time to be using OSM data.

Is there already any use of OSM data for geocaching?

Yes – it’s possible to use an OSM on many Garmin GPS units. Some regularly compiled data files with contour lines are available here, and there are even datasets which can be used for routing with Garmin units too.

So how will Ammotin use OpenStreetMap data?

I’m creating a rendering aimed at geocachers and walkers. The plan is to have good terrain rendering, possibly following the OpenCycleMap design but I may experiment with hill shading. Even in areas where the map is incomplete, the terrain should give some idea of what to expect. Road network will be pretty standard, but I will ensure that car park areas are well presented.

The raw elevation data will come from the Shuttle Radar Topography Mission. What I’m aiming to do is create a set of tiles corresponding to OSM map tiles, but providing elevation data. I’ll spin that off as “OpenHeightMap” or something similar. The aim is to foster more use of such elevation data, but also to try and gather user-contributed corrections for the numerous (but small) pockets of missing data from the shuttle mission. If you want to read more about those voids and how they can be filled, there’s a great paper on the subject. The Scottish Mountaineering Club have also done some good work with this data.

Is the data good enough?

I’m been impressed with the data in the UK, but there’s still lots of mapping still to be done. However, I believe that even in areas where the mapping is incomplete, the OSM data will still provide a good cartographic depiction to aid decision making, if only because of the elevation data and features which have been mapped.

Will Ammotin allow me to contribute back to OSM

I certainly hope so. My plan is that once upload your tracklog from a days walking into Ammotin you notice that part of your walk doesn’t appear to be on a footpath marked on the map. So, you highlight the relevant portion of the tracklog and choose “Send to OpenStreetMap” and away it goes. It would then guide you in selecting an OSM tool for editing the map based on your submitted tracklog.

So will any other maps be supported

I’ve written Ammotin to enable other mapping sources to be plumbed into it. In the UK, I’d really like to be able to offer Ordnance Survey maps. I’m enquiring about how I might be able to do that so fingers crossed.

If you know of a map source you’d like to see, get in touch!