[Tilecache] Some general Newb questions

[Christopher Schmidt]

On Tue, Dec 04, 2007 at 06:37:57PM -0800, cmose wrote:
> What I tend to get is, once I
> load up my map, the initial tiles will show up in my map div (typically
> about 6 tiles), but then there will be about 60 more image requests after my
> viewable tiles have already shown up. This happens pretty much every time I
> drag the map. Furthermore, rendering of cached tiles is still not terribly
> performant.

Using CGI or mod_python?

> Frequently a tile in the middle of the viewable area will not render until
> all the rest of those tile requests for, I presume, "unvisible" tiles
> complete. I've tried playing with the OpenLayers buffer setting but this
> does not appear to have much of an impact.

That seems unusual, and makes me wonder if perhaps you set it wrong. A
webpage which demonstrates these problems would be most helpful: if not
that, at least an HTML snippet showing your map and layer creation would
be good.

> Also (I hate asking two questions in one post but don't want to clutter) I
> can't seem to get the OpenLayers overviewmap control to function at all; I
> get nothing but pink tiles in the overview control.

http://trac.openlayers.org/wiki/TroubleshootingTips

"""
If you have 'pink tiles':

    * Right click on the image, and get the image URL (via 'properties'
    * in IE, or 'copy image URL' in other browsers)
    * Paste the image URL into a browser. 
"""

http://openlayers.org/pipermail/users/2007-November/003953.html
"So, the overview map control is trying to guess at the resolutions it 
should use for its map.  And it's not guessing right in this case.  So 
the solution is to be explicit.  Choose some resolutions that you know 
TileCache will like:"

> And finally - just as a sanity check, I'm trying to use tilecache_seed.py. I
> set it up to seed my first layer of zoom, that worked fine and pulled down
> something like 800 tiles. 

Um, this sounds totally out of line with what I expect. That said, given
the fact that you had 800 tiles in your first zoom, it doesn't surprise
me at all that you got the numbers you did for the rest of the layers.
(WEll, it sort of does, since the numbers don't entirely add up, but
they're all within the right order of magnitude). 

> Thanks again - I know I haven't provided many concrete details about my
> configuration; I'm currently at home and don't have that information handy.
> I believe I'm using TileCache 1.9 and OpenLayers 2.5 and running TileCache
> under mod_python on Apache 2.2 on a windows box (just remembered - I also
> have extent_type=loose, if I'm recalling the wording of that parameter
> correctly).

Your tilecache config section and your OpenLayers HTML will both help
debug these issues further.

Regards,
-- 
Christopher Schmidt
MetaCarta