[OSM-dev] coastline

Jon Burgess jburgess777 at googlemail.com
Thu Aug 14 21:38:15 BST 2008

On Thu, 2008-08-14 at 09:43 +0100, Dave Stubbs wrote:
> On Wed, Aug 13, 2008 at 9:25 PM, Jon Burgess <jburgess777 at googlemail.com> wrote:
> > Even with a large overlap the squares are still visible at zoom 2. I'm
> > not sure this is a big problem though. I was going to try running the
> > code again with DIVISION=1. Last time I tried I got a segv after about 5
> > hours in SHPDestroyTree(). It looked like a buffer or array overflow.
> > Perhaps something between 1 and 400 with a larger overlap would work.
> >

Today I got another segv using DIVISIONS=400, TILE_OVERLAP=10000 on the
planet dump. It appears to have overflowed the state->seg_list[100].
Setting this to MAX_SEGS=1000 fixed the crash. I added a counter to
print the maximum value of state->seg_count and strangely it only seemed
to hit 97 so I can't quite explain why it crashed with MAX_SEGS=100.

> If it's any help the current cyclemap is running with OSM coastlines
> at all zooms -- we're using inverted coastlines (ie: painting sea, not
> land).
> What I did was set DIVISIONS=100 and the overlap to 10% of a tile...
> that works fine.
> Unfortunately I didn't run anything through any simplifiers... so it
> takes bloomin ages to render each tile at zooms 1-3... but still...
> first steps.

I've just deployed a simplified shapefile based on DIVISIONS=400,
TILE_OVERLAP=10000 and it is used for zoom 0 - 9. The machine is busy
rendering things right so the tiles are quite a mix of old and new right


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