Change rendering natural=desert #773
Comments
|
tile.openstreetmap.fr fork is doing this well |
|
See also http://wiki.openstreetmap.org/wiki/Talk:Tag:natural%3Ddesert Current desert polygon data is mostly an exercise at abstract art, like: http://www.openstreetmap.org/#map=8/28.060/-3.521 The global average node distance of desert areas is probably something like 20-50 kilometers and i have yet to see any area tagged natural=desert that is properly mapped under any universal definition of desert. Rendering landforms like deserts which naturally have no well defined boundaries as colored polygons does not really make much sense, especially not at zoom levels >= 8. I would have suggested removing those from the style long ago but sadly i see no real chance in such a suggestion being successful. |
The minimum zoom levels are currently rather inconsistent. For example meadow and farmland have a different minimum zoom level. This PR aims to improve this. This PR lets all major landuse start at z10 (like most do already), except for wood / forest. Smaller objects will start at z10. Concrete changes in minimum zoom levels: * tourism=camp_site, tourism=caravan_site, tourism_picnic_site from z13 to z10 * landuse=quarry from z11 to z10 * landuse=garages from z12 to z13 * landuse=farmyard, landuse=farm, landuse=farmland from z9 to 10 * landuse=village_green from z11 to z10 * natural=desert from z8 to z10 (solves partially gravitystorm#773) * aeroway=apron, aeroway=aerodrome from z12 to z10 * highway=services, highway=rest_area from z14 to z10
The minimum zoom levels are currently rather inconsistent. For example meadow and farmland have a different minimum zoom level. This PR aims to improve this. This PR lets all major landuse start at z10 (like most do already), except for wood / forest. Smaller objects will start at z13. Concrete changes in minimum zoom levels: * tourism=camp_site, tourism=caravan_site, tourism_picnic_site from z13 to z10 * landuse=quarry from z11 to z10 * landuse=garages from z12 to z13 * landuse=farmyard, landuse=farm, landuse=farmland from z9 to 10 * landuse=village_green from z11 to z10 * natural=desert from z8 to z10 (solves partially gravitystorm#773) * aeroway=apron, aeroway=aerodrome from z12 to z10 * highway=services, highway=rest_area from z14 to z10
The minimum zoom levels are currently rather inconsistent. For example meadow and farmland have a different minimum zoom level. This PR aims to improve this. This PR lets all major landuse start at z10 (like most do already), except for wood / forest. Smaller objects will start at z13. Concrete changes in minimum zoom levels: * tourism=camp_site, tourism=caravan_site, tourism_picnic_site from z13 to z10 * landuse=quarry from z11 to z10 * landuse=garages from z12 to z13 * landuse=farmyard, landuse=farm, landuse=farmland from z9 to 10 * landuse=village_green from z11 to z10 * natural=desert from z8 to z10 (solves partially gravitystorm#773) * aeroway=apron, aeroway=aerodrome from z12 to z10 * highway=services, highway=rest_area from z14 to z10
Can somebody provide counterexample? Because it would be a good point againt rendering natural=desert. |
* This resolves gravitystorm#773 * This resolves gravitystorm#780
|
I think many uses of natural=desert, at least in Africa and Australia, try to cover the concert of an Erg. They are also sometimes tagged as natural=sand. Perhaps that's the better tag? Or we can just concur that natural=desert does not refer to the climatological definition of desert, but to the "folk-definition" of desert, which seems to basically equal sand dunes / ergs. It is not entirely clear to me what the tag natural=desert in the United States tries to convey, though. |
|
In Northern Africa and the Middle East many desert polygons roughly follow the sand deserts but this is not generally the case elsewhere. Especially in the Basin and Range Province in North America the desert tag is commonly used for the valleys which only rarely contain significant sand areas. This can also be seen in the name tags (see for example: http://www.openstreetmap.org/#map=10/38.0551/-116.6446). |
|
Yes, that's basically what I said, right? :) Why do Americans see the valleys as desserts? I suppose the climate is basically the same as in the ridges in between? Is the difference based on vegetation? |
|
These valleys are in many cases deserts in the sense they are fairly dry and with only sparse vegetation while precipitation is higher in the mountain ranges around resulting in more vegetation there. But the polygons are fairly crude and do not usually map the vegetation divisions but the topography. Typical appearance is like this: http://commons.wikimedia.org/wiki/File:2014-07-18_17_26_54_Panorama_of_Railroad_Valley_from_U.S._Route_6_eastbound_about_90.8_miles_east_of_the_Esmeralda_County_Line_in_Nye_County,_Nevada.JPG The few sand deserts that exist there are usually mapped as natural=sand like here: http://www.openstreetmap.org/#map=12/36.6531/-116.5584 |
|
I'd consider those two fairly typical deserts in my experience. A few years back I went on a camping trip through the Australian outback, which took me through the edges of deserts, and it was somewhat similar. I'm not sure what typical use of |
|
Problems with natural=desert is that (almost?) always it is completely impossible to show line with desert on one side and not a desert on the other. Wiki page documents why this is a bad tag. I am now convinced that this tag should not be rendered. |
Ergs (sand deseets) have very sharp borders though. |
Maybe, but natural=desert, in name, definition and usage includes also other kinds of terrain. |
|
Interesting topic. If we wanted to keep rendering "natural=desert", I would make it much more neutral and grey-ish. Or outline the area, similar to national parks, to show the extent of the whole "desert" area, no matter what the exact parts of it are. |
Ergs (sand dunes) are better tagged as natural=sand. Other type of dunes don't have strict borders. This resolves gravitystorm#773.
Ergs (sand dunes) are better tagged as natural=sand. Other type of dunes don't have strict borders. This resolves gravitystorm#773.
Ergs (sand dunes) are better tagged as natural=sand. Other type of dunes don't have strict borders. This resolves gravitystorm#773.
Fully agree with these observations about the the near total impossibility to define exact and meaningful boundaries for deserts, and that is why almost no map shows an outline or polygon fill for deserts, but just a label showing the "approximate" location of the desert. And that is the way natural=deserts should be rendered, IMO. Look at the attached image, at scale 1:1M. Combined with contours, the OSM desert data starts to make sense. Dropping the rendering of natural=desert completely, including labelling, will lead to a significant loss in some areas like the Western US. Admittedly, contours are vital for making sense of the labels... but that is true for many other rendered "landform" related features like cliffs, ridges, peaks etc. The "kaki" brown patches by the way in some of the desert valleys, are patches of natural=mud as tagged in OSM. They actually seem to correspond with the nearly flat lower sections of the valleys, below the screes running of the side of the mountains, quite well, as can be seen in this Google Maps link of the same area:
|
The following issue has been moved over from trac:
I know that till today the proposal of the desert feature is not approved ( http://wiki.openstreetmap.org/wiki/Proposed_features/Deserts) but it is rendered in Mapnik already.
The problem is the kind of way the desert is rendered today. The rendering doesn't make sense at all as you can see here: http://www.openstreetmap.org/?lat=30.374&lon=34.836&zoom=9&layers=M
The color needs to be changed as it doesn't make sense to show a desert that dark in brown. Desert should not be darker than a forest and as there is a lot of life and also villages in this area. The desert shouldn't be that present in Mapnik!
###### The name of the desert is not showing at all at the moment. This is of course not very helpful. If a big desert is defined it should on some zoomlevels show the name of the desert.
currently the zoomlevel = showing of desert doesn't make sense. The desert gets rendered already in zoom=8 in dark brown. The same way as the forest gets rendered in zoom=8. In zoom=9 the landuse farmland is rendered and in zoom=10 also landuse=sand is added. It looks very much like a swiss cheese.
In zoom=13 there is no desert rendered anymore.
###### Summary
The whole concept of showing the desert has to be reconsidered. The current displaying doesn't make so much sense.
We consider in Israel to remove the whole desert just because it is showing this strange way. I know that we shouldn't map to a renderer but in this case it looks just to bad to keep it this way.
Please see this thread in the discussion board: http://forum.openstreetmap.org/viewtopic.php?id=14806
The text was updated successfully, but these errors were encountered: