> From: David [mailto:[email protected]] > Sent: Thursday, May 09, 2013 10:48 PM > Subject: Re: [talk-au] OpenStreetMap in Government > > Further, so much OSM data ends up in a psql database, one > column per tag. Believe it or not, psql does not like having column > names start with numerals. It can be worked around but I suspect that's > one reason mapnik (or more correctly, its slippery map) won't show > 4wd_only.
Column names beginning with numerals are fine in PostgreSQL. You have to quote them, but that's not a big issue. You have to quote the "natural" column too as natural is a reserved word in SQL. The technical issues preventing styling based on 4wd_only on tile.osm.org, the default osm.org layer, are threefold: 1. To add a column to the database on yevaud (the tile.osm.org rendering server) would require a database reload. The hstore feature can now be used to avoid this, but hstore is relatively new and not enabled on yevaud. It could be enabled, but again this would require a database reload. I think the last database reload was in 2011. 2. The mapnik stylesheet (osm.xml) used for tile.osm.org is horrendously hard to edit and does not have a maintainer. I guess this isn't really a technical issue, but it's tied up with the next one 3. The tile.osm.org stylesheet has been ported to carto, an easier language to write stylesheets in. Unfortunately, it is slower and deploying this new stylesheet is waiting on a hardware upgrade. This is also related to the database reload. Two non-technical issues are 1. There is no cartographer maintaining the osm.org stylesheet. Deciding what to include and what not to include takes a design skill that I know I don't have. 2. Unlike other layers, the tile.osm.org layer has a strong influence on how mappers tag. For this reason care needs to be used when adding new tags, because what's rendered is much more likely to be tagged. For what it's worth, if I was maintaining the tile.osm.org style and a patch came in adding some kind of indication of 4wd status to it, I don't know if I'd accept it. I've traveled the 4wd roads in Australia so I know how their terrain matters, and I've also studied it at work, the problem is the style already shows too much information. Thankfully, it's not up to me as I don't have cartographic design skills. Of course if no one proposes a change to the stylesheet with a patch, we'll never have that discussion and there's no chance of adding it then. _______________________________________________ Talk-au mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-au
