It is very interesting Peter. I need to try the geofabrik data, but I also did a test with the cloudmade data that gave me a strange result. 1. I imported in (database1) in Postgres data from massachusset.2. I imported in (database2) in Postgres data from connecticut. Connecticut shares a border with massachusset. I generated tiles from database1, everything ok. After, I generated tiles from database2. The tiles were all generated in the same TilesCache. What happened is for some zoom level the tiles of massachusset disappeared. What I thought is that Connecticut was generating missing tiles for Massachusset. It looks like there is no way to fix that.
> Date: Fri, 24 May 2013 23:39:09 +0200 > From: [email protected] > To: [email protected] > Subject: Re: [OSM-dev] About the geographic data in a .osm file > > Just to avoid confusions: The Geofabrik extracts does not cut along the > borders exactly, too. > They should be better (I guess), but not exact. > Exact splitting is much more expensive in terms of time and memory than > splitting a rough bounding polygon. That polygon should contain the > whole country, but may contain additional areas to reduce complexity. > > And - of course: As far as I know none of the available extract services > splits ways or areas (except multipolygons probably) when exporting, so > if a way crosses the border, it's usually contained completely in the > extract. > > regards > Peter > > Am 24.05.2013 23:16, schrieb Vince Berubey: > > Thanks Toby,you answered exactly what I was trying to understand. > > - I do understand why i'm getting blank tiles.- I wanted to know why there > > is data outside of delaware. > > I do understand know. > > > > Date: Fri, 24 May 2013 16:12:33 -0500 > > Subject: Re: [OSM-dev] About the geographic data in a .osm file > > From: [email protected] > > To: [email protected] > > CC: [email protected] > > > > > > First of all, did you notice that the cloudmade extracts are over a year > > old? I would suggest looking at geofabrik for up to date > > extracts:http://download.geofabrik.de/north-america.html > > > > As for your tiles quesion, I'm not quite sure what you mean. Are you asking > > why there is any data outside of Delaware? Or why you are getting blank > > tiles where you don't have any data? > > > > The cloudmade extracts never were too accurate on the state borders. When I > > first downloaded Kansas they were missing the north border by a couple of > > miles and had extra on the south. So it doesn't surprise me that the > > cloudmade extract has extra data in it. > > > > As for tile generation, the tile rendering process doesn't care about where > > you do/don't have data. It just renders the tiles you tell it to render. If > > there happens to be no data in that area then the tile will be blank. > > > > Toby > > > > > > On Fri, May 24, 2013 at 3:08 PM, Vince Berubey <[email protected]> > > wrote: > > > > > > > > > > I have downloaded "delaware.osm.bz2 " > > http://downloads.cloudmade.com/americas/northern_america/united_states/delaware#downloads_breadcrumbs > > > > The boundary box I used when I generated my tiles from Generated_tyles.py > > were a little bit bigger than the Delaware region. > > What I don't understand is why I was able to generate tiles that were in my > > boundary box, but outside the Delaware area. > > > > So, the .osm file does not exactly contain only the geographic data from > > the region that you have downladed? > > Please look at this file, the red marks are the Delaware borders. I have a > > lot of tiles generated outside of these borders: > > > > http://postimg.org/image/ogwbjz5ln/ > > Thank you for any explanation about it. > > Best regards. > > > > > > > > _______________________________________________ > > > > dev mailing list > > > > [email protected] > > > > http://lists.openstreetmap.org/listinfo/dev > > > > > > > > > > > > > > > > _______________________________________________ > > dev mailing list > > [email protected] > > http://lists.openstreetmap.org/listinfo/dev > > > > > _______________________________________________ > dev mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/dev
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