yvecai's diary

Recent diary entries

piste:grooming documentation

Posted by yvecai on 7 April 2019 in English (English)

I found the piste:grooming description from the ‘Piste maps’ ( or the Key:piste:grooming ( pages that was derived from the earlier not very clear. I’ve made an attempt to re-write it to document actual usage here:

I’d like to have some comments if you think I missed something. This is about actual usage and better comprehension. If the values re-used from one type of piste to another does not suits you, it’s another story that can be dealt with later.


Opensnowmap style re-write and bug fixes

Posted by yvecai on 7 March 2019 in English (English)

I’m genuinely pleased when people tell me about bugs or improvements related to OpenSnowMap map style by emailing me or by openning issues in github1,2. So, the least I can do is to try to fix them.

I’m happy to announce that a new style is being rolled out on OpenSnowMap that address some of them.

Here is an overview of the visible changes. For a better knowledge of the technical background, suffice to know that the piste database is now powered by Imposm instead of Osm2pgsql, and that the style is written in cartoCSS instead of bare mapnik XML.

Nordic and Crosscountry Skiing - Can I ski there ?

As the maintainer of OpenSnowMap, one thing I don’t want is to send your reckless grandma in an icy, treacherous slope. I’s also like to avoid to invite you to try an un-groomed backcountry piste you spot on the map with your skates.

So now, if piste:difficulty or piste:grooming is not mapped on piste:type=nordic ways, the piste shows a ? question mark on the map. Also, if not fully tagged, the more you zoom, the fainter the piste become. The goal of making the map less nice-looking is to ensure that lazy mappers will look twice at their contributions.

On the other hand, if you map properly the grooming type, icons and a dashed pattern will appears to distinguih between:

piste:grooming=classicclassic piste:grooming=skatingskating piste:grooming=scooterscooter piste:grooming=backcountrybackcountry Just have a look at the Oslo area to see what it means.

Also, if you tag the relevant section of any piste way with the proper piste:difficulty, you will see the small warning pictogram appear just where it’s useful, and not everywhere.

If difficulties are color-coded in your area, OpenSnowMap knows how to take care of the colour tag applied to a type=route, route=piste, piste:type=nordic relation. This is probably where you’d like to put this colour, while actually map the difficulty of every way composing the piste according to the wiki description for nordic pistes.

For those who wonder, the default XC pistes colors is the one in my area. If it’s not the same where you ski, map the relations colours.

Skitour and Backcountry Downhill

For ages, a skitour descent is explicitely described in the wiki as to be mapped as piste:type=downhill, piste:grooming=backcountry. Sorry, I missed that until now. Both piste:type=downhill, piste:grooming=backcountry and piste:type=skitour are now displayed with the same kind of dot pattern and the small backpacker-wearing skier icon. Also they are are painted with the same difficulty color-code than downhill runs.

Only the piste overlay is updated for now

The piste+relief overlay and the base map are too big to be re-rendered now. We have to wait for the northern hemisphere summer to see that happening without overloading the server. When this happens, the base map forest color will be dimmed down so that the XC pistes stand out more on the map.

Opensnowmap Legend

The map legend now looks like this: legend

Opensnowmap style reload

Posted by yvecai on 12 November 2018 in English (English)

I’ve figured out recently that base map (topo) renders underground water pipes like plain rivers. It will need a database reload to fix this. Certainly I can correct other glitches at the same time, so have you spotted or can you find something else really wrong with this style? I’m mainly interested in mountainous places, of course, don’t expect fixes in Manhattan subway lines ;-) The style is derived from OSM-bright. Thanks in advance, Yves

Are you joking ??

Posted by yvecai on 16 February 2017 in English (English)

No, seriously, c’mon! "map screenshot with lots of small squares"

I had to check on to see if my Opensnowmap has a problem. No, it’s perfectly fine. But fine for who ?

It’s not like there is no mapper in the US, as at least one of them made something like this a very long time ago (6 years). Is there anybody in the US using OSM? Is there any US-based company using OSM? It seems a bit stupid to do so at first sight, isn’t it?

The SnowMap base layer

Posted by yvecai on 22 September 2016 in English (English)

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 only showcased on for now. 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 will be 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.

SRTM global 1 arc second release complete

Posted by yvecai on 16 August 2015 in English (English)

For those interested in DEM data, the release of void-filled, 1 arc-second and global SRTM data is now completed at USGS. See