[OSM-talk] Mapnik: strange prioritisation/appearance of place names

Steve Chilton S.L.Chilton at mdx.ac.uk
Mon Mar 23 19:08:43 GMT 2009


Just to add to Andy's comment, the logic heirarchy for the mapnik slippy map goes like this:
place=country comes in at z2
place=city AND capital=yes comes in at z4
place=city (not capital) comes in at z6
place=town comes in at z9
place=suburb comes in at z12
place=village comes in at z12
place=hamlet comes in at z14
Both country and city stop being rendered later on, as they would not be relevant.
All others should render right through.
There are other nuances such as point size changing at various points, and some changing to grey, but that is not relevant to this discussion.
If anyone has any workable additions to this arrangement, that will work with the current DB, I am happy to hear them and consider implementing.
If additional nuances are agreed on (population, importance_value, or whatever) then please let me know when that is in place and I will try to figure a way of filtering this into the picture.
It is not always possible to predict mapnik's placement clashing decisions, but I have assumed that as these are rendered before most stuff (painter model remember) that they would take precedence over symbols and stuff coming later - but correct me if I am wrong.
 
Cheers
STEVE

	-----Original Message----- 
	From: talk-bounces at openstreetmap.org on behalf of Andy Allan 
	Sent: Mon 3/23/2009 6:09 PM 
	To: Tom Hughes 
	Cc: talk at openstreetmap.org; Woll Newall 
	Subject: Re: [OSM-talk] Mapnik: strange prioritisation/appearance of place names
	
	

	On Mon, Mar 23, 2009 at 3:04 PM, Tom Hughes <tom at compton.nu> wrote:
	> Woll Newall wrote:
	>
	>> It's unclear to me to me how to get this question direct to the people
	>> who configure the OSM Mapnik slippy map layer - Should I just enter it
	>> as a bug into the bug report area on the mapnik.org site? I took a
	>> look at the existing bugs thre and they seem to be about "Mapnik", not
	>> "the Mapnik-created slippy map on the OSM site".Does anyone know how
	>> to report such things?
	>
	> What you're looking for is the mapnik component on
	> trac.openstreetmap.org but (a) we know about the issue and (b) there is
	> already at least one bug there for it.
	
	And I'd encourage you (Woll, that is) to have a look at the mapnik
	style rules file. Whilst long and moderately complex, I can see you're
	interested in the problem enough that it's worth your while seeing how
	it works rather than trying to reverse-engineer the end result.
	
	http://trac.openstreetmap.org/browser/applications/rendering/mapnik/osm.xml
	
	So you can see in the section starting with
	<Style name="city">
	That there are four rules for showing city names, and the lowest one
	also has a minimum scale. So at a given zoom level, city names stop
	showing up. The min scale of 20000 equates to it showing on zoom 14
	but not 15.
	
	Cheers,
	Andy
	
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