Math1985's diary

Recent diary entries

SOTM Heidelberg

Posted by Math1985 on 1 October 2019 in English (English).

This year, I was invited to visit the State of the Map conference in Heidelberg as a scholar. Obviously, I would like to thank the OSM Foundation for sponsoring me. In addition to being a frequent mapper, I am also a maintainer of openstreetmap-carto (the default stylesheet on, and this role was the main reason I was visiting the conference. At the conference, I met with Paul, Christoph (who I had never met before in real life) and Andy. We had some discussions on the future of the stylesheet, including a public ‘bird of a feather session’, in which we met with other community members.

One of the things that has been on the horizon for quite a while is vector tile rendering. During the conference, we drafted an action plan for getting a vector rendering ready. Some choices need to be made: do we start from scratch, or do we continue with the current map design? Do we render the vector tiles on the client side, or do we translate vector tiles to raster tiles on the server? Which software will we use to generate the vector tiles? On the stylesheet side, some technical changes need to be made, fortunately most of which are relatively simple. Unfortunately, even with these changes made it seems that performance remains a significant limitation. By now, the first steps on the action plan already have been completed. There is still a lot of work to do (including technical challenges to solve), but we have been making progress in this area for sure.

OpenStreetMap Carto release v4.6.0

Posted by Math1985 on 17 December 2017 in English (English).

Today, v4.6.0 of the openstreetmap-carto stylesheet (the default stylesheet on the OSM website) has been released. Once changes are deployed on the it will take couple of days before all tiles show the new rendering.

Changes include:

  • Change sports_centre and stadium color to light green
  • Change shades of green for landuse/leisure=recreation_ground and garden
  • Do not render glaciers and icesheets on z6 and z7
  • Do not render very small water areas on low zoom
  • Do not render small national parks and nature reserves
  • Do not render ferries on z7
  • Improve rendering for bus guideways
  • For built-up areas, replace the external data on z8 and z9 by OSM data
  • Do not render bicycle/motorbike parking icons to z17
  • Render community_centre and social_facility areas in light yellow

Thanks to all the contributors for this release, including Andy Townsend, a new contributor.

For a full list of commits, see…v4.6.0.

As always, we welcome any bug reports at

OpenStreetMap Carto release v3.3.1

Posted by Math1985 on 22 May 2017 in English (English).

Today, v3.3.1 of the openstreetmap-carto stylesheet (the default stylesheet on has been released.

This version includes a single change: * Fix a regression in intermittent waterways

For a full list of commits, see…v3.3.1

As always, we welcome any bug reports at

Analysis of usage of similar tags over time

Posted by Math1985 on 31 August 2016 in English (English).

Recently, a new tool was created by Martin Raifer (@tyrasd) to generate graphs of the usage of tags over time. This is a great tool that gives us more insight in what drives the choice of tags by mappers. In this diary, I compare the usage of some related tags.

amenity=public_building versus office=government versus office=administrative

amenity=public_building versus office=government versus office=administrative

We can see that amenity=public_building was added to the map features page wiki in March 2006, before it even was used once in the wild. The tag started being used later that year, and usage increased rapidly from there on. No increase in usage could be detected when JOSM or Potlatch added support for the tag. Growth in usage slowed down in 2013, and in 2014 even a decrease started. I wonder if anybody has a hypothesis for the cause of this decrease.

office=government was added to the wiki in May 2010, when two objects were tagged as such. After the features was documented on the wiki, usage immediately increased. The tag office=administrative was added to the wiki in September 2011, when about 180 objects with this tag were in use. The increase of the usage of office=government and office=administrative sped up when iD added support in October 2013.

Full timeline:

  • 2006-03-24 wiki: amenity=public_building added to map features
  • 2007-10-16 JOSM: amenity=public_building added
  • 2008-02-21 wiki: amenity=public_building page created
  • 2010-05-25 wiki: amenity=public_building marked as ‘do not use’
  • 2010-05-25 wiki: office=government created
  • 2010-07-09 Potlatch 2: amenity=public_building supported
  • 2011-09-06 wiki: office=administrative created
  • 2013-02-18 wiki: amenity=public_building marked deprecated in map features
  • 2013-10-30 iD: office=administrative, office=government added
  • 2015-11-15 JOSM: office=administrative, office=government added
  • 2016-03-02 wiki: office=administrative and amenity=public_building deprecated
  • 2016-04-01 JOSM: amenity=public_building dropped and deprecation warning added

shop=seafood versus shop=fishmonger

shop=seafood versus shop=fishmonger

Usage for both tags was around 15 shops until voting and documentation started. Potlatch 2 added a preset for seafood despite fishmonger winning a vote. When Potlatch 2 added the preset, the tagging of seafood strongly increased (despite the vote and documentation supporting fishmonger). When JOSM added seafood half a year later, usage of this tag rapidly grew too, causing two similar tags to exist in parallel. A deprecation warning for fishmonger on the wiki had little effect. In 2013, iD added fishmonger, but moved to seafood a year later. When iD moved to fishmonger, the number of newly tagged fishmongers dropped rapidly, and later even the total number of fishmongers decreased, allowing seafood to become significantly more popular. When JOSM added a deprecation warning for fishmonger, the drop intensified.

This is a clear case where the choice of tag is driven by the editor of the user (see the increase of seafood and fishmonger when Potlatch 2 and JOSM added their preset).

Full timeline:

  • 2010-06-06 voting: seafood shop accepted (and fishmonger rejected)
  • 2010-06-06 wiki: seafood page created
  • 2010-07-09 Potlatch 2: fishmonger added
  • 2010-07-29 wiki: seafood added to map features
  • 2010-10-16 JOSM: seafood added
  • 2013-03-20 iD: fishmonger added
  • 2013-09-14 wiki: fishmonger page created and marked as deprecated
  • 2014-04-08 iD: fishmonger dropped, seafood added
  • 2014-07-22 openstreetmap-carto: seafood and fishmonger rendered as dot
  • 2015-07-31 openstreetmap-carto: fishmonger and seafood rendered as fish
  • 2015-12-26 JOSM: deprecation warning for fishmonger added

amenity=swimming_pool versus leisure=swimming_pool

leisure=swimming_pool versus amenity=swimming_pool

When documentation started in 2009, amenity and leisure had both about 100 instances. This slowly increased until in 2011, suddenly the use of amenity exploded. It is not clear to me why, does anybody have an explanation? After a vote for leisure, a change of the wiki and a deprecation warning in JOSM, usage of amenity decreased.

Full timeline:

  • 2009-12-27 wiki: leisure page created (as redirect to key:leisure)
  • 2010-10-11 wiki: leisure added to map features
  • 2010-12-01 wiki: amenity page created (including mention of a proposal to merge with leisure)
  • 2010-12-23 Potlatch 2: leisure added
  • 2011-02-20 wiki: content added to leisure page
  • 2011-10-27 JOSM: leisure added
  • 2013-03-18 iD: leisure and amenity added (amenity as non-searchable)
  • 2016-01-22 voting: amenity discouraged
  • 2016-01-22 wiki: amenity page marked as discouraged
  • 2016-01-23 JOSM: deprecation warning for amenity added

shop=musical_instrument versus shop=musical_instruments

shop=musical_instrument versus shop=musical_instruments

Initially the plural was more popular. However, the singular started being used more and more when a wiki page was created and when JOSM added support for the singular, overtaking the plural in 2011. A mechanical edit in 2014 removed the remaining tags.

Full timeline:

  • 2010-07-27 wiki: singular page added to map features
  • 2010-07-28 wiki: singular page created
  • 2010-10-16 JOSM: singular added
  • 2013-09-15 wiki: plural page created
  • 2013-10-19 voting: plural marked as discouraged
  • 2013-10-21 wiki: plural page marked as discouraged
  • 2014-01-01 wiki: plural page removed
  • 2014-01-01 mechanical edit: changed all plural into singular
  • 2014-07-22 openstreetmap-carto: add seafood and fishmonger as dot
  • 2014-08-26 iD: singular added

shop=bookmaker versus shop=betting

shop=bookmaker versus shop=betting

When documentation started in 2013, about 400 shops of each type were created. Increase of both tags was about equal, until bookmaker was approved by a vote, the wiki was adapted, and iD added a preset for bookmaker. Then the use of bookmaker exploded, but since these three events were so close in time, it cannot be determined which of them was responsible for this. Usage of the tag grew rapidly after iD and JOSM support was added.

Full timeline:

  • 2013-09-12 wiki: bookmaker and betting pages created
  • 2014-01-19 voting: bookmaker approved, betting
  • 2014-01-19 wiki: betting page marked as discouraged
  • 2014-02-16 iD: bookmaker added
  • 2014-02-17 JOSM: bookmaker added
  • 2014-07-22 openstreetmap-carto: bookmaker and betting added as dot
  • 2015-10-02 openstreetmap-carto: betting dropped
  • 2015-12-26 JOSM: deprecation warning for betting added

For those who want to run their own analysis, the tool can be found at, and the source at

OpenStreetMap Carto release v2.42.0

Posted by Math1985 on 3 August 2016 in English (English).

Dear all,

Today, v2.42.0 of the openstreetmap-carto stylesheet (the default stylesheet on has been released.

Changes include:

  • Add rendering of amenity=charging_station and tourism=artwork
  • Change icon of shop=department_store
  • Increase font size for various labels
  • Change playground color
  • Various bug fixes

Thanks to all the contributors for this release, including David Gianforte, a new contributor.

For a full list of commits, see…v2.42.0

As always, we welcome any bug reports at

Kind regards, Matthijs Melissen