[OSM-dev] OpenLayers problem with latitude and longitude placement

Thomas Wood grand.edgemaster at gmail.com
Mon Dec 8 18:00:07 GMT 2008

2008/12/8 Thomas Wood <grand.edgemaster at gmail.com>:
> 2008/12/7 Andreas Titz <erddaten at fahrrad.streckenfun.de>:
>> Maarten Deen wrote:
>>> Thomas Wood wrote:
>>>>The maxResolution option on the Map object is currently not doing
>>>>anything at a guess, this is what is causing the vectors to disappear
>>>>at >z13
>>> I've found out that the length of the vectors is affecting at which zoomlevels
>>> they disappear. The longer they are, the sooner they disappear. So it must be
>>> some kind of bug.
>> It seems to be a clipping problem. If you zoom to the end of such a
>> line, it will be visible even at zoom 18:
>> <http://www.maasluip.nl/ebt/test.html?lat=50.99996&lon=9.99998&zoom=18&layers=B0T>
>> I guess, if you zoom to the center of the line, the endpoints are too
>> far away. In that case OL assumes, that the line won't clip the actually
>> shown map.
>> HTH, Andreas
> Thanks for that example, I've passed it onto somebody who knows better
> than me about the rendering internals.

Apparently this is a known issue:
(17:54:18) crschmidt: Yeah, that's a side effect of very large
geometries and too small of a resolution
(17:54:30) crschmidt: specifically, geometries which are larger than
the cairo rendering space are the problem here, I think
(17:54:43) crschmidt: but I'd suggest that the issue be minimized
slightly more and brought to the OL mailing list
(17:55:33) crschmidt: there was a bunch of work in this regard in 2.7
that i can't even pretend to understand

I'd recommend making up a simplified test case and taking it to the
OpenLayers list. (users at openlayers.org or dev at openlayers.org)

Thomas Wood

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