A combined approach makes sense to me. Then people can choose if they want to use the tracktype tag or continue using just the surface tag (either may make sense in different communities; I'd guess the German community will prefer to use tracktype only with highway=track). I think the following values of the surface tag could be considered paved: [none] (no surface tag present), paved, asphalt, concrete, concrete:lanes, concrete:plates, paving_stones, sett, grass_paver, cobblestone, metal, wood, tartan. All other values, including new and undocumented values, could be unpaved by default. How about this? Moreover, TagInfo ( http://taginfo.openstreetmap.org/keys/?key=surface) lists a few other undocumented values that may be considered paved, such as cobblestone:flattened (same as sett? to be discouraged?), bricks and interlock (both similar to paving_stones?), cement (quite similar to concrete?), stone and rocky and rock and limerock and granite (similar in practice to sett or cobblestone?).
I also agree with using a dashed line (same visual language of Carto's tracks) instead of grains, which may be harder to see (say, against the somewhat darker red background of a primary way). But I also like malenski's idea of red and blue outlines for the other situations he has pointed out, both seem quite intuitive to me. Anyway, I'd bring this part of the discussion (visual aesthetics) out of the tagging list. Only answering your question, Google renders unpaved roads as fainter and thinner streets (http://goo.gl/maps/9ErFf), but only at distant zoom levels. Bing.com renders them fainter and golden, but only at distant zoom levels (http://binged.it/1cY5c01). Here.com renders them slightly fainter and grayer at any zoom level ( http://here.com/-29.9938308,-51.1125391,14,0,0,normal.day). These examples may, however, simply reflect a different "classification" that these companies adopt - maybe they have decided to map these streets as something similar to living streets. Navigon (the satnav program I used before switching to OSM-based apps) makes no visual distinction. I'll ask the Brazilian community if they have more examples with other GPS software. Nonetheless, I believe a more distinctive marking such as dashed lines would be preferred by most people. On Wed, Jan 1, 2014 at 12:41 PM, Matthijs Melissen <i...@matthijsmelissen.nl > wrote: > On 1 January 2014 13:35, Fernando Trebien <fernando.treb...@gmail.com> > wrote: > > If nobody disagrees, I'll consider that the tracktype tag is the best > choice > > for this decision, and that any value besides grade1 deserves some > marking > > meaning it's not in what most people consider "good condition". > > Personally, I'm not a fan of using tracktype for this purpose. I don't > like tracktype in general, because the semantics is impossible to > guess without referring to the documentation, and hard to remember. > The numbers also don't have a precise semantics, apart from the > description on the wiki. > > Of course, we could use a combination of both approaches, i.e., render > both tracktype 2-5 and surface=unpaved/ground/etc as unpaved roads. > > How do commercial maps render unpaved tracks in Brazil (or elsewhere)? > In the Netherlands, dashed outlines are used, hence why that would be > most intuitive to me, but I can imagine different systems are used > across the globe. > > There is also a discussion on Carto's Github on this topic: > https://github.com/gravitystorm/openstreetmap-carto/issues/110 > > -- Matthijs > > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > -- Fernando Trebien +55 (51) 9962-5409 "The speed of computer chips doubles every 18 months." (Moore's law) "The speed of software halves every 18 months." (Gates' law)
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