[Tilecache] Two tilecache instances not behaving identically.

[Gissur Þórhallsson]

Hello,

I've got a peculiar problem.

I have two tilecache services running on two separate machines. Let's call
them LIVE and SEED.

LIVE is in an active production environment delivering tiles to our clients
and works without a hitch.
SEED is an machine I have in-house on which I generate caches for LIVE.

LIVE is running:

   - Ubuntu Server 8.04. LTS
   - Apache 2.2
   - Python 2.5.2
   - Tilecache 2.11 running under mod_wsgi

SEED is running:

   - Ubuntu Server 10.10
   - Apache 2.2
   - Python 2.6.6
   - Tilecache 2.11 running under mod_wsgi


I've been accessing TileCache from OpenLayers using TMS requests for a while
and it seems to work fine - but if I try WMS requests I run into a problem.

Here is a an overview of what I'm facing, the following are snips from the
same OpenLayers client:
Live WMS <http://i.imgur.com/K58Qu.jpg> - ok
Seed TMS <http://i.imgur.com/nbnMA.png> - ok
Seed WMS <http://i.imgur.com/z3QdR.png> - not ok

Here are the configs for these layers. <http://pastebin.com/KN74QT2Y>

If I inspect one of those missing Seed WMS tiles at the following URL (split
up for readability):
http://SEED/tc/tilecache.py
?LAYERS=SEED
&FORMAT=image/jpeg
&SERVICE=WMS
&VERSION=1.1.1
&REQUEST=GetMap
&STYLES=
&EXCEPTIONS=application/vnd.ogc.se_inimage
&SRS=EPSG:3057
&BBOX=*296528.80598333,408528.80598333*,450057.61196667,562057.61196667
&WIDTH=256
&HEIGHT=256

I get the following:
An error occurred: Current x value 296528.805983 is too far from tile corner
x 143000.000000

These same coordinates work fine against LIVE - and if I take the  x value
and round it up I get
An error occurred: Current y value 408528.805983 is too far from tile corner
y 255000.000000

If I round the y value also ending up with:
BBOX=*296529,408529*,450057.61196667,562057.61196667

I suddenly get the correct image.

So what that tells me, unless I'm missing something (which I guess I must
be), is that LIVE and SEED are not handling the coordinates the same way on
SOME tiles.
Which makes no sense what-so-ever.

Anybody have any ideas?


-- 
Gissur Þórhallsson

Loftmyndir ehf.
Laugavegur 13
IS 101 Reykjavík - Iceland
sími (tel): (+354) 540 2500
tölvupóstur (email): gissur at loftmyndir.is
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/tilecache/attachments/20110311/aac4d460/attachment.html