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mercredi 18 décembre 2019

New server is being deployed - URL change

Dear users, A generous donation accelerated the deployment of on a more powerful server. No big changes, except a faster rendering and the possibility to serve more tiles. This will help in following the increasing number of requests for ski maps.

Many thanks to the team at !

Part of the map requests are already handled by this new server, so you may experience a longer load time while the tile cache is building up.

If you are using the ski map tiles on your own website, please use the url, tile serving from will soon be deprecated. Also, heavy users (> 50'000 tiles per day) are requested to access the tiles via their own cache.

mercredi 30 octobre 2019

Keep an eye on map changes

Some of you may already use the daily and weekly change view of to check for changes on the ski pistes they mapped.
Today, this view have been improved and now gives more information about the actual change. Is this a way, a relation deleted, a simple node moved? A new processing associated with a detailed legend will help to better understand the changes and maybe spot errors.

See, yesterday apparently someone seems to have refined a nicely mapped skating ring.


This view coupled with the select_thin_64.png button will allow you to find more information about the modified element. It is still a bit frustrating not to be able to check on deleted elements, I will try to add daily and weekly .html change list to allow this.

In practice, each night, the pistes of the OpenStreetMap database at 00:00 GMT are compared to the pistes that were there the day and the week before. Geometries are simplified in order not to display to much information.

lundi 14 octobre 2019

Opensnowmap desktop version refreshed too

After the mobile version, the desktop version have been refreshed to a more actual look, keeping the same features and as always, a big ski map !


mardi 1 octobre 2019

Refresh mobile page

I spent a couple of hours to refresh the mobile version of style and icons.


Let me know if you like it. Maybe I've seen the website too often myself, but I find the new one refreshing.

For the record, here was the old design:

mardi 21 mai 2019

Site maintenance mai 2019

Rendering is off for a few days due to database reload. Sorry for the pink tiles !


dimanche 6 janvier 2019

Pistes de fond dans le jura: ce qui reste à mapper

L'Espace Nordique Jurassien partage le tracé des pistes de ski de fond depuis l'espace pro de sa carte interactive (carte dispo ici ).

Ces tracés sont d'origines diverses, et il ne fait pas sens de les copier dans OpenStreetMap. Cependant, cela permet une comparaison, et on peut voir ainsi que près de la moitié des pistes de ski de fond du Jura français ne sont pas mappés dans OSM ! Sans surprise, les coins les plus courus et les plus enneigés sont mieux cartographiés que les autres.

J'en ai fait une carte qui permet de savoir ou poser vos skis cet hiver pour compléter, c'est ici: et Espace Nordique Jurassien: Pistes de ski nordiques manquantes dans le Jura blog_enj.png

Parmi les sites les plus mal servis, on trouve:

  • Belleydoux
  • Bolandoz
  • Chaux des Prés
  • Frasne
  • Le Haut Saugeais Blanc - Hauterive La Fresse
  • La Malmaison
  • La Combe Saint Pierre
  • Le Lac des Rouges Truites
  • Les Combes Dernier
  • Les Crozets
  • Les Granges Dessus
  • Longchaumois
  • Le Meix Mussy
  • Menthières
  • Nods
  • Saint Laurent en Grandvaux
  • Val de Vennes

Je vous souhaite bien du plaisir à découvrir ces sites lorsque la neige sera en quantité suffisante !

jeudi 11 octobre 2018

New piste preset for iD

I made some modification in the ski piste presets for the iD editor. This is mainly intended to differentiate the meaning of piste:grooming and piste:difficulty tags depending on the type of piste (downhill, nordic, hike, etc ...).

Descriptions are according to the wiki, which is rather stable for years.

Maybe some want to give it a try here to see if everything looks fine: iD master preview.

vendredi 21 septembre 2018

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 of pistes, downhill and cross-country combined, we are the biggest global ski pistes 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 ski area 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 areas missing 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 of nordic skiing areas.

What have I found ?

First a really good news : both projects contributors can still have a lot 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 vs OdBL). 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 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, 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 Open Database License (ODbL) by the OpenStreetMap Foundation (OSMF). by is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

samedi 15 septembre 2018

At last !

A the mobile version, the menu now closes when you pan the map. This bothered me for years, but I always forget to fix this.

Check on

vendredi 24 août 2018

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 runs mapped 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 ski areas-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 !

lundi 1 mai 2017

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 app uses 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.

jeudi 23 février 2017

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



dimanche 8 janvier 2017

http (s) ://

OpenSnowMap goes secure, on request.


So, if you're afraid someone might want to hack your favorite run, or simply to enable location in chrome, change your bookmarks.

lundi 19 septembre 2016

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 12 pixels 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 384px tiles and display them with a 1.5x scale factor. That please my eyes on my own phone 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 so you can check your mapping mistakes and correct them before I 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.

mardi 23 août 2016

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).


lundi 6 juin 2016

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, the total 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 in OSM ? Why does some people map alpine ski pistes as area without a median line that would allow routing?

jeudi 17 mars 2016

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.


mardi 1 mars 2016

New version of Opensnowmap

A new version? Wait ... nothing has changed !

Well hopefully it's the case. website has been rewrote with a cleaner code separating HTML, CSS and Javascript. Also, a few good practises in website design have been implemented. For instance there is no blocking calls to the server any more.

There is some changes for the user, though:

  • Language change can be done on the fly, no need to reload the page.
  • Mobile version has been redesigned a little, allowing you to keep the map in view while looking for pistes with the 'Search' input.
  • A 'Donate' button landed on the menu, it's not only here to look nice.

As the code is now cleaner, don't hesitate to propose some changes yourself on the website, it's here on Github . Be kind enough to report bugs, I made some tests on a few browsers, but there may things I missed.


dimanche 25 octobre 2015

Relief updated

Hillshade, contour lines and elevation profile calculation have been updated to a complete 1 arc-second resolution on


samedi 11 juillet 2015

New hillshading on

The relief (hillshading) layer on have been updated. On the major part of the world, resolution jumps to 30m instead of 90m beforehand, thanks to the ongoing release of 1 arc-second SRTM data by NASA.

To mak a long story short, the relief is more precise by a x1.5 zoom factor.

For more details, here are the data used on the serveur to generate the hillshading.
Screenshot from USGS explorer on Google-map background

30m SRTM data are used where available. Up north, data comes from the EU-DEM for scandinavia, ASTER for Alaska, Canada, Greenland and Russia. In an area extending from Greece to Iran, I had to kept the 90m SRTM data from CGIAR, I hoipe to be able to update this area soon.

To assemble those datasets, I use a script based on python-gdal to merge the data by small 1x1° tiles, filtering SRTM data by a 3x3 average filter and ASTER by a 10x10 filter to reduce noise. Gdal utilities then re-assemble everything in a big Tiff. For rendering, I took the opportunity to pré-calculate smaller Tiff at lower zooms to reduce the load on the tile server. The map should show up more fluidly.

Contour lines will be updated from the same datasets, if I can optimize them enough to fit my disks.

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