[Tilecache] cells not being calculated correctly for bounding box

[Soenke J. Peters]

Hi,

Frédéric Junod wrote:
> Just tested the trunk version and http://trac.tilecache.org/changeset/385
> breaks my config: I always have the "Current x value XXX is too far
from tile
> corner x XXX" error.

I have also run into a similar problem when trying to get a "tilecached"
layer via GDAL using its WMS driver.

A quick look at the code in GDAL shows that if rounding occurs, it is
done via ceil() (value + 0.5, then typecast to int).

Another incompatibility of TileCache with GDAL seems to be the way
resolutions are calculated.
In TileCache, resolution is max(resolution_x, resolution_y), whereas
GDAL_WMS uses both for calculations.
So, the bbox width/height of a layer in TileCache must be square to work
with GDAL WMS minidriver, or a multiple of the top level tile numbers
(TileX, TileY for GDAL_WMS) when using GDAL tileservice/worldwind.

PS:
Changes in the calculation of tile bounds might invalidate cached tiles.
Maybe a version tag should be added to the cache.

Bye,
Soenke
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