From the tilecache mailing list….
Hi Everyone,
Really appreciate all the replies…
1. Installed Imaging-1.1.6.tar.gz (PIL).
[root@rupert-linux ~]# python
Python 2.3.4 (#1, Mar 10 2006, 06:12:09) [GCC 3.4.5 20051201 (Red Hat 3.4.5-2)] on linux2 Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> print sys.path
['', '/usr/lib/python23.zip', '/usr/lib/python2.3', '/usr/lib/python2.3/plat-linux2', '/usr/lib/python2.3/lib-tk', '/usr/lib/python2.3/lib-dynload', '/usr/lib/python2.3/site-packages',
'/usr/lib/python2.3/site-packages/PIL',
'/usr/lib/python2.3/site-packages/gtk-2.0']
>>>
2. Modified test1.cfm
41 var options = {
42 controls: [new OpenLayers.Control.MouseDefaults()]
43 };
44
45 map = new OpenLayers.Map( $('map'), options);
46
47 var layer_base = new OpenLayers.Layer.WMS(
48 "Base Layer",
49 "#request.mapserv_tile#",
50 {
51 map: '/home/map/beijing/new/wms.map',
52 layers: '#request.basemap_tile#',
53 format: 'image/png', 'transparent': 'false'
54 }
55 );
56
57 var layer_road = new OpenLayers.Layer.WMS(
58 "Road Layer",
59 "#request.mapserv_tile#",
60 {
61 map: '/home/map/beijing/new/wms.map',
62 layers: '#request.roads_tile#',
63 format: 'image/png', 'transparent': 'true'
64 },
65 {
66 reproject: false
67 }
68 );
69
70 map.addLayer(layer_base);
71 layer_base.setIsBaseLayer(true);
72
73 layer_road.setIsBaseLayer(false);
74 map.addLayer(layer_road);3. tilecache.cfg. Commented metaTile=true http://222.128.19.19/tilecache/tilecache.cfg
47 [basemap]
48 type=WMSLayer
49 url=http://127.0.0.1/cgi-bin/mapserv?map=/home/map/beijing/new/wms.map
50 layers=district,greens,major_river,minor_river
51 #bbox=-180,-90,180,90
52 #metaTile=true
53 extension=png
54
55 [roads]
56 type=WMSLayer
57 url=http://127.0.0.1/cgi-bin/mapserv?map=/home/map/beijing/new/wms.map
58 #layers=road4,road4label,road3,road3label,road2,road2label,road1,road1label,road11,road11label
59 #bbox=116.1737,39.8211,116.5640,40.0799
60 #maxresolution=1.40625
61 #bbox=-180,-90,180,90
62 layers=road1,road1label,road11,road11label
63 extension=png
64 #metaTile=true4. Modified wms.map http://222.128.19.19/tilecache/wms.map
OUTPUTFORMAT
NAME png
DRIVER "GD/PNG"
MIMETYPE "image/png"
IMAGEMODE RGB
EXTENSION "png"
FORMATOPTION "INTERLACE=OFF"
END5. Checked access_log. “transparent=true” exists…
192.168.1.150 - - [30/Mar/2007:13:46:26 +0800] "GET /tilecache/tilecache.py?MAP=%2Fhome%2Fmap%2Fbeijing%2Fnew%2Fwms.map&LAYERS=r
oads&FORMAT=image%2Fpng&TRANSPARENT=true&SERVICE=WMS&VERSION=1.1.1&REQUEST=G
etMap&STYLES=&EXCEPTIONS=application%2Fvnd.ogc.se_inimage&SRS=EPSG%3A4326&BB
OX=116.334229%2C39.891357%
2C116.345215%2C39.902344&WIDTH=256&HEIGHT=256 HTTP/1.1" 200 14580
Now, this is really weird. I have “transparent”: true in test1.cfm all the time. That didn’t worked.
For every test iteration i made, I always tried clearing the cache, removing the python compiled scripts, then restarting Apache just to get a clean state..
rm -Rf /usr/local/apache2/htdocs/tmp/*
rm /wwwroot/tilecache/TileCache/*.pyc
/etc/init.d/httpd restart
Then I tried appending “transparent=true” to tilecache.cfg based on Eric’s suggestion…
That worked. Now I wonder why… Nevertheless, its working now. Again many thanks to everyone…
Rupert
On Fri, Mar 30, 2007 at 01:57:43PM +0800, Rupert de Guzman Jr wrote:
> Hi Everyone,
>
> Really appreciate all the replies…
> Then I tried appending “transparent=true” to tilecache.cfg based on
> Eric’s suggestion…
> That worked. Now I wonder why… Nevertheless, its working now. Again
> many thanks to everyone…
TileCache pays almost no attention to the URL: Only the BBOX and the layername matter. Anything else is simply ignored: so your transparency being set in OpenLayers actually has 0 affect.
The reason for this is that TileCache can only store one copy of an image. If the URL parameters modified the content, you could get an inconsistent cache.
This is ‘by design’, insofar as there is no obvious solution (other than to complain more loudly when TC Gets parameters it isn’t expecting, which is an outstanding FIXME in the code). The lack of error message is not by design, and I’m sorry you got bit by the poorly documented behavior.
Regards,
–
Christopher Schmidt
MetaCarta