Quoting Jon Burgess <[EMAIL PROTECTED]>: > On Mon, 2008-06-23 at 22:09 +0200, [EMAIL PROTECTED] wrote: >> Hi all, >> >> I'm having a problem with mod_tile. I'm using it together with Mapnik >> to render an overlay map, so I need a transparent background in tiles. >> Mapnik does this just fine by setting attribute bgcolor="transparent" >> in osm.xml file. However, mod_tile groups the mapnik tiles into a >> .meta file and the transparency gets lost there. When I use >> convert_meta to unpack the meta file, the background is black. >> Somebody had the same problem here either, >> http://www.nabble.com/layer-transperancy-td16639745.html >> but the thread seems to be dead already with no solution. >> Could somebody please look at it? Hope it is not too complicated to fix. > > The problem is with the Mapnik code that does the conversion to 256 > colours. The discards the alpha channel (see include/mapnik/octree.hpp). > > You can fix this by using the PNGA output instead. Edit gen_tile.cpp in > mod_tile and change the two references of png256 to png. > >> I tried to override the problem by swithing the meta-tiling off by >> commenting out the >> #define METATILE (8) >> line in render_config.h. Separate png files are actually good enough >> to me since my overlay is quite simple. But I run into few compiling >> problems, which I was unable to fix. >> Thanks for any advice or fix! > > I've submitted a bunch of changes to SVN which allow the code to be > compiled and run in non-meta tile mode. This does not make any > difference to the transparency issue. If you update the METATILE value > then you need to be careful to recompile and reinstall both the render > daemon and Apache module. > > The changes also move the map style, font and plugin locations to the > render_config.h file so there should be less need to edit any other file > when configuring the module from now on. > > Jon > >
Hi, thanks Jon! The change from png256 to png helped. I somehow presumed, that the image format requested by mod_tile is the same as what comes from mapnik's generate_tiles.py, which was wrong. Thanks again! mendrejk _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/dev
