Comparison of and OpenStreetMap data

I have ask myself for some time now how I could have an estimation of the completeness of OpenStreetMap when it comes to ski pistes. I’m certain that with our more than 100’000 km ofpistes, downhill and cross-country combined, we are the biggest global skipistes database of this type, but what exactly remains to map? I needed something to compare to.

There is this great site called where contributors can upload scans and photos of ski maps from their favorite ski area. They have more than 3000 skiareas listed. These ski areas location are crowd-sourced by their contributors, and offers an open API. So I can certainly find a way to compare this with OpenStreetMap data, no ? Yes, so I did. And many thanks to Russel for making !

The comparison goes both ways, first there is a long list called Pistes missing from

Then we have a map showing Ski areasmissing in

It’s not perfect, because there are OSM ways on one side that are not really(or rarely) grouped as ‘ski resorts’ and single points on the other side. So of course in some case the distance threshold chosen (5km) is maybe not the best, and in some case ski area localization could be improved.

OpenStreetMap ‘ski areas’

No, they are not built-in in the OSM database. There is the tag ‘landuse=wintersports’ to tag ski resorts, but it is seldom used. The rejected relation proposal ‘site=piste’ attracts even less contributions.

So for this comparison they are build in a database like this :

The pistes from OSM are buffered by 500m, then glued in big polygons. Very big polygons (>30km) are split in equal size rectangular chunks ranging from 20km to 40km. This is a bit arbitrary but allows to more or less efficiently separate interconnected ski areas.

In the end, this gives >3500 downhill ski areas, and the same number ofnordic skiing areas.

What have I found ?

First a really good news : both projects contributors can still have alot of fun contributing for a while. excels in the USA, and is better in Europe.

At first glance around 800 ski areas can be found in but not in OpenStreetMap. For, a lot of small and micro downhill resorts are missing (apparently > 1500). For nordic skiing, it’s really worse, but it’s not really the target audience I guess.

Also, OSM seems more complete when it comes to lifts (aerialways) than for ski pistes themselves. I would risk an explanation here. There is a lot of gondolas enthusiasts (,,, …), and I suspect people are mapping lifts systematically. Armchair mapping is also possible for aerialways on the contrary to ski pistes.

How does it helps ?

Both project’s data have open license, but not compatible (CC-BY-SA vsOdBL). So each can be used for the other as an inspiration, but not as a direct data source. Needless to say ski maps uploaded at are for the vast majority copyrighted and not to be used for mapping at OSM.

For contributors, they can use the map produced to spot a ski area in OSM, investigate on the web and find documentation of interest for the project. For OSM contributors, well, as usual : find a place with ski pistes to map, take a train ticket, your gear and GPS, and go !

More also have some more information about its ski areas, for example if they are closed. This could be used to spot places in OSM where some map curating is needed. Also, I spotted on the maps some isolated pistes in OSM that looks strange. In short, some idea for ski-related QA in OSM.

Copyright notice

OpenStreetMap® is open data, licensed under the Open Data Commons OpenDatabase License (ODbL) by the OpenStreetMap Foundation (OSMF). by is licensed under a Creative CommonsAttribution-Noncommercial-Share Alike 3.0 United States License.

Ski pistes mapping 2018

It’s been a few years since the last statistics about ski pistes mapping in Openstreetmap.

You know it: Openstreetmap has the biggest worldwide skimap available. And still growing !

From today stats:

  • Crossountry trails: 67961 km
  • Alpine runs : 37287 km
  • Lifts: 17647 km
  • Sled runs : 1376 km

While at a slower pace than in the glory years, the length of the ski runsmapped in OSM grow every year with several thousand of kilometers. This means that there is still some ski pistes to map, and a good question is how many ? I’m trying to have some clue in comparing other available skiareas-related listings, such as Russel’s excellent I’ll keep you informed.

Edit : Ah, it’s more than 100’000 km of ski pistes without the lifts now !

2017 style improvements

I make no mystery of it: I’m a cross-country skier. I’ve run alpine skis only twice in my life, and definitely prefer the wild and quiet areas where you’re alone sweating your way in the middle of nowhere. This had had consequences on, and I did not spent enough time on downhill runs rendering style. It was crowded and definitely not clear enough, but this is about to change. Now that the ski season is almost done, I’m rolling out a major style change.

Alpine runs

Downhill ski runs are now cleaner (I hope). Especially transition is smoother between pistes mapped as areas and those mapped as ways. At high zoom,pistes let a clear view on the contour lines and fade in better on the topo-style base map.


The less common pistes type (skitours, snowshoes, sled, and sleigh) are now rendered with icons. Curling, ice-stock and hockey icons have been added.

Pistes overlaps

Sometimes pistes can be used for several activities, now Opensnowmap is able to render piste tagged like piste:type = downhill;sled or other combination.

I hope this improved map will please you, and you are welcome to make any remarks or request improvement here.

External users

As long with the new style, the tiles URLs changes. As your website or appuses a proper referer, I am able to contact you with the new URL, of course. The URL is http(s)://{z}/{x}/{y}.png.

For the offline users, please note that the monthly .mbt tile set from 28.04.2017 is the last one available with the old style.

Improved ski ressorts rendering renders ski ressorts at zoom 10,11 & 12. For this, it takes either site=piste relations or landuse=winter_sports polygons, and checks what type of pistes they contain (downhill, nordic, sled,etc…) in order to display small icons next to the ressort name.

Until now, these icons where pre-calculated images of all possible combinations.They were not so nice, and did not scale well with the big tiles used on the mobile site.So I built a very handy font file, called Ski.ttf, that looks like this:

This allows me to use Mapnik list-placement on TextSymbolizers to position the needed icons nicely.

It will takes some time for the tiles to re-render, so here what it looks like:

before / after comparison

The Snow Map base layer

When Mapquest layer disappeared, this was a problem for OpenSnowMap: its cold colors and less detailed style were great to overlay ski pistes onto. But the end of this freely available map forced me to build a simple style with plenty of room for ski pistes: the OpenSnowMap Base Snow Map.

A winter topo map

I used OSM-Bright to start building this style. Using colder colours more suited to a winter map, of course I also added relief. In particular, relief hillshading led me to desaturate highways to avoid they pops out the shadowed side of the hills. Ski pistes are not rendered on this layer, the OpenSnowMap remains an overlay. In fact, they *are* rendered on the Base Snow Map with 12pixels wide transparent labels that forbids other labels to take place where ski pistes from the OpenSnowMap overlay will land.

I want to see it!

This style is live on The mobile part of the website is shown with ‘retina tiles’ by default, but you can choose this high-dpi option or not from the menu. For these mobile-friendly tiles, I choose to render 384pxtiles and display them with a 1.5x scale factor. That please my eyes on my ownphone and the server seems to be OK with them, so please tell me they also looks good on your phone or tablet.

Of course, Openstreetmap-carto is still available, although without high-res tiles but a simple scaling for the mobile version. Here also let me know what the default should be: I find it more usable with the scaling on my device, although a bit pixelized.

That’s great, but …

Unfortunately, the use of the layer outside OpenSnowMap is discouraged by referer magic and so on. Also, tiles containing ski pistes are pre-rendered,but not the others. So while the Imposm-powered DB is up-to-date and a few minutes behind Openstreetmap, don’t expect super-performances in tile refresh. Yes, 10 minutes behind so you can check your mapping mistakes and correct them beforeI take them into account, isn’t it clever ? This new base map won’t change much the OpenSnowMap overlay tiles that will remains pretty much the same and updated daily.

Opensnowmap Tile Usage Policy

Opensnowmap offers overlay tile layers for ski pistes and winter sports. Two sets of tiles are available: one with only the pistes, and another one with relief background (shaded relief and contours lines).

It seems that the layer with relief information is of great interest, even in summer.

Sadly, opensnowmap server won’t be able to cope well with the demand on next winter, so in order to keep the server healthy for skiers, the tile usage condition from outside Opensnowmap will change as follow :

  • From the 1st of october 2016, a valid referer will be mandatory to fetch tiles from
  • From the 1st of november 2016, access to tiles with relief from outside is not granted anymore and can stop at any time (likely around the 1st).


More than 100’000 km of ski pistes and lifts on the map!

When you enter, there is a small counter that shows you the length of ski pistes and lifts there is in OSM each days. On june 6th, thetotal length of alpine and crosscountry ski pistes, skitour, snowshoeing, lifts and sleds pistes crossed the 100’000km line.

Not bad, isn’t it ? This number seems important, so I searched and found a few flaws in my count, you can find the queries here. I notably found a few thousand of km of crosscountry pistes mapped as relations, without pistes tags on ways that were missing on previous calculations.

Anyway, now, we can claim that on 2016-06-06T00:03:02Z, there was 108’084 km of winter sports pistes in Openstreetmap ! Two and a half tour of the planet !

Before OSM, does anybody figured out that there is so many pistes dedicated to winter sports on the globe ? And how much is still to be mapped inOSM ? Why does some people map alpine ski pistes as area without a median line that would allow routing?

More ski map for your mobile

Elevation profiles and ski resorts statistics are now available for the mobile version of

I wanted to avoid displaying vector data on the map, this can cause performance issue on mobile devices. The elevation profile is now calculated with Matplotlib, along with a image view of the piste to help vizualize the information on a small screen.

Pistes statistics are calculated from OSM data, on resorts enclosed by a landuse=winter_sports polygon or in a relation of type=site, site=piste.