[Tilecache] Current y value 5009377.084000 is too far from tile corner y -0.000800

[Christoph Lingg]

Am 01.11.2010 um 15:05 schrieb Yves Moisan:

> Le 2010-11-01 05:58, Christoph Lingg a écrit :
>> 
>> Hi list,
>> 
>> I had a running tilecache map server and recently I updated tilecache to the newest version. Using the same tilecache.cfg as before, 50% of the tile requests are running as before, but the other half end up with an error like:
>>> An error occurred: Current y value 5009377.084000 is too far from tile corner y -0.000800
>> I am struggling around with this error for a couple of hours now, having tried out a lot of parameters. My configuration is very very basic:
>> 
>> OpenLayers:
>>> var options = {
>>>  projection: new OpenLayers.Projection("EPSG:900913"),
>>>  maxExtent: new OpenLayers.Bounds(-20037508.34,-20037508.34,20037508.34,20037508.34),
>>>  resolutions: [19567.879237500001, 9783.9396187500006, 4891.9698093750003, 2445.9849046875001, 1222.9924523437501, 611.49622617187504, 305.74811308593752, 152.87405654296876, 76.43702827148438, 38.21851413574219, 19.109257067871095, 9.5546285339355475, 4.7773142669677737, 2.3886571334838869],
>>>  units: 'm'
>>> };
>> 
>> Tilecache:
>>> [kmt]
>>> type=Mapnik
>>> mapfile=/home/christoph/render/style.xml
>>> spherical_mercator=true
>>> tms_type=google
>> 
>> 
>> Has there been changed something since the last tilecache updates? I am not able to explain the origin of this error? Does anybody has a hint?
> Hi Christoph,
> 
> Not a hint but a related problem.  I experienced the same issue a couple of weeks ago but in my case I got the ".. too far from corner ..." error messages after I updated to a newer version of OpenLayers from r10165 (2.9+) to r10848 (2.10+) with the same TC code.  I can't say for sure that the change in OL version is the cause because there are other bits of code in my environment, but I have a feeling it has to do with a slightly different way of computing something that has to do with bbox.  
> 
> I didn't investigate the issue past a quick SVN diff because I figured I will just dump the current cache and have it regenerated with whatever TC wants for resolutions when I'm ready to switch environments.  But I am concerned that putting newer versions bring about issues like that.

Salut Yves,

this is an interesting aspect, I also upgraded OpenLayers from 2.8 to 2.10. My problems occurred while using OL 2.10, but after some investigation I found out that same problems arise using OL 2.8. So I assume the problem is caused by the current tilecache version.

I could confirm this assumption as I replaced temporarily tilecache version 2.11 with 2.03.

In version 2.04 the changelog shows a change concerning the spherical mercator:
>  * Minor fixes to layer initialization with regard to spherical mercator,
>    error logging, and others.
http://svn.osgeo.org/tilecache/trunk/tilecache/docs/NEWS.txt

I seems like a bug, doesn't it? Or is there somebody who knows more about that?

Christoph
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