OpenStreetMap
That blade of grass is coming back to haunt us.
Posted by Little Brother on 19 July 2017 in English.Remember that comment about the map being first finished when every blade of grass has been documented. Of course it was only meant to be figurative but some contributors do go to extraordinary extremes to map useless data.
Using OSMI I found this:
When downloaded these ways are are tagged as barrier=line
They are the ground white lines of a tennis court: An entry from a contributor which has over 4,000 changesets to his/her credit. I know that there are no fixed set of attributes so what this contributor has done is within OSM rules but I think such data is redundant as they will never be rendered. But maybe this contributor is writing his own renderer.
So what’s my problem: Well, it is that the data is not being entered without mistakes which the validation applications find. If not corrected then the users who try to clean-up the data base will be continually linked to these errors which is of course a waste of resources.
Basically it comes down to the fact that many POIs can be well enough documented with a single node or area with the applicable attributes. It would then be easier for everybody.
I don’t like to delete the work of others but it give little pleasure to see redundant data like detailed water slides, etc where a single node would do the job better.
Discussion
Comment from Stereo on 19 July 2017 at 12:14
For what it’s worth, the French style draws the lines on tennis courts and football fields automatically along the rectangle, e.g. http://tile.openstreetmap.fr/?zoom=19&lat=49.63175&lon=6.11431&layers=B000000FFFFFF
Comment from Little Brother on 19 July 2017 at 12:39
Well, it certainly looks lovely, but how useful is it
Comment from Vincent de Phily on 19 July 2017 at 18:40
One of the main goal of most renderings is to look lovely, so it’d be reason enough. Plus it’s actually useful to know what kind of sport is played on a particular field.
Concerning the OP, see this help.o.o question for a previous discussion about it. I’m still of the opinion that we shouldn’t map pitch lines, but this is apparently not unanimous.
One thing that commenters agreed on is that barrier=line is the wrong way to go. You should tell the contributor to find a better scheme. Maybe also him the french and german rendering styles, as well as this issue for the default osm.org style, it might satisfy his wish without bloating the db.
Comment from nebulon42 on 19 July 2017 at 20:18
At osm-carto we deliberately removed rendering for barrier=line (more specifically rendering for barrier=*) to discourage tagging for the renderer. It was rendered in the past, but now is not rendered any more. See https://github.com/gravitystorm/openstreetmap-carto/pull/1986 for details.
Comment from Warin61 on 19 July 2017 at 22:37
The orientation of a sports pitch might be usefull to determine if the court faces sunrise/sunset or prevailing winds. For that reason I tag the individual pitches of a group of tennis courts rather than a collective way for them all. I see no point in tagging the lines on the ground .. the shape of the court has enough information.
The sport= tag gives the type of sport played, with at least 3 exceptions; ‘football’ (soccer, australian_football, american_football, rugby?), ‘hockey’ (field_hockey, ice_hockey) and ‘multi’ (just list the sports semicolon separated). There are enough of these to fix to keep someone busy for quite a while.
Barrier=* is usefull … some of the ones I tag restrict pedestrians from crossing at dangerous places.
Comment from nebulon42 on 20 July 2017 at 17:36
My comment might have been misleading. We have not removed all barrier renderings, but restricted them to some meaningful values to prevent something like barrier=line.