About map rendering

[David White]

Hello all,

I have two question about rendering using the vector maps. The enclosed
screenshots where taken using the car renderer.

Q1. How does the renderer decide which town name to display and with
what size font?
SC..005.png shows this area
http://www.openstreetmap.org/?lat=50.7252&lon=1.6133&zoom=12&layers=M
The big grey area in the middle is the town of Boulogne-sur-Mer, 45K
pax, whose name did not get displayed, while "Le Portel" is displayed
(black dot above o) but the dot below the 'e' is the town center for
"Outreau" which is a larger town does not appear.

Also, top right corner, "Rupembert" appears, but is a hamlet numbering
max 20 houses...

Q2. What drives the displaying of the ref tag?
SC...027.png shows this area
http://www.openstreetmap.org/?lat=50.4861&lon=1.6238&zoom=13&layers=M
and the ref tag for the D 940 is displayed 6 times, this is a bit of an
over-kill, as it prevents displaying other information.

Is this because the road has been split to accomodate different speed
restrictions or street names and hence the same ref tag appears many times?
Should ref tags for ways be better input as relations? Would the
renderers cope with it?

Regards,

David

[Victor Shcherb]

Hi 

That looks like feature investigation. I think we can raise it in Issues of googlecode with screenshots. Most probably text doesn't have priority to show or is not sorted in proper way.

The issue can be difficult if sorting order depends on zoom level than it requires changes in rendering. For now I can not say anything about why some text is displayed second is not. It is like chaotic but algorithm that calculates intersection prevent showing text over text and as I see works pretty good :)

2011/8/2 David White <dgkw...@gmail.com>

[Sergei Beilin]

The same effect here - at some scale the 1.5M Samara title disappears
while 10K towns are shown ;)

[Hardy]

Please have a look at Issue 572 (at
http://code.google.com/p/osmand/issues/detail?id=572&sort=-id&colspec=ID
Type Status Priority Summary Opened Milestone).

This exactly addresses the issue on town names mentioned above, I
think. Still waiting for anybody to respond to that issue. But it
seems to be a rather generel problem we still have in Osmand.

[Victor Shcherb]

It is discussible: I mean if all cities have tags "city" and "town" than it is defenitely map source issue. Because application doesn't know what "town" is bigger, probably analyzing additional tags can help.

But now Osmand supports only 1 tag/value for object due to other issue.

2011/8/3 Hardy <hm.gg...@googlemail.com>