[OSM-talk] Here's what they do in Korea

[John Harvey]

One of the problems I think we have is road widths.  Mapnik currently 
renders all highways of the same type the same width - it ignores lanes 
and width:

http://wiki.openstreetmap.org/wiki/Lanes (2,117,599 usage with highway)
http://wiki.openstreetmap.org/wiki/Key:width  (560,000 usage with highway)

If you check the style sheet:

http://trac.openstreetmap.org/browser/applications/rendering/mapnik/osm.xml

(look for bits like this:)
<Rule>
<Filter>[highway] = 'trunk' and not [tunnel] = 'yes'</Filter>
&maxscale_zoom17;
&minscale_zoom18;
<LineSymbolizer>
<CssParameter name="stroke">#a9dba9</CssParameter>
<CssParameter name="stroke-width">15.5</CssParameter>
<CssParameter name="stroke-linejoin">round</CssParameter>
<CssParameter name="stroke-linecap">round</CssParameter>
</LineSymbolizer>
</Rule>

No references to lanes.

(If you care, using this handy table: 
http://wiki.openstreetmap.org/wiki/FAQ#What_is_the_map_scale_for_a_particular_zoom_level_of_the_map.3F 
, you can compute that at zoom level 17 at 45 degrees latitude, we will 
always draw a highway=trunk 15.5 pixels * 1.689 = 26.2 meters wide - at 
3 meters a lanes, that is roughly 8 lanes wide.).

I once tried rendering with highways fixed widths and then overridden 
using Lanes or width if the data was present.  The results are 
"interesting".   There are roughly 45 million highway = * ways.  That 
means roughly 1 in 20 (optimistically) have a lanes tag.  Image a way 
for bridge has a lanes tag but the ways connecting to it doesn't.  You 
wind up with a fat bridge connected to skinny highways - not as nice 
looking as the map we currently present.

I believe our rendering of highway widths solution is currently in a 
local maxima - it looks pretty now, but to move forward we may need to 
make it look less pretty until the underlying data gets even better.  
(This is similar to the innovators dilemma).  To make this change to our 
primary renderer will require courage.

John


On 64-07-22 11:59 AM, Arun Ganesh wrote:
> I am totally blown away by the level of detail provided by the map 
> providers in Korea. Even the navigation devices they use in almost any 
> vehicle is of a much higher level than anything I have seen outside. 
> As the car approaches a flyover or a junction, the device actually 
> renders a 3d view of the area from the pov of the vehicle, with 
> detailed buildings, trees and lighting to match the time of the day. 
> Each lane of the road is marked with turn restrictions and speed limits.
>
> All the gloating we do of the capabilities of osm fades in comparison 
> to what's been achieved here. We are years away from reaching such a 
> level where it will possible to crowdsource data to such a detailed 
> level in a consistent manner.
>
> On Thu, Nov 3, 2011 at 9:00 PM, <talk-request at openstreetmap.org 
> <mailto:talk-request at openstreetmap.org>> wrote:
>
>
>
>     http://local.daum.net/map/index.jsp?t__nil_navi=bestmain&nil_id=map <http://local.daum.net/map/index.jsp?t__nil_navi=bestmain&nil_id=map>
>
>     http://map.naver.com/
>

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