quantization does not seem to support transparent backgrounds (regardless of gd or agg) I'll file a bug about this but I don't know if it will be fixed for 5.0
tb On 8/30/07, Gilles Bassière <[EMAIL PROTECTED]> wrote: > Hi List, > > I run Mapserver 5.0 beta5 as a WMS server and have some troubles with > background transparency :( > > In a first attempt, I just replaced my GD OUTPUTFORMAT definition by: > > OUTPUTFORMAT > NAME "png" > DRIVER "AGG/PNG" > MIMETYPE "image/png" > IMAGEMODE "rgba" > EXTENSION "png" > FORMATOPTION "transparent=on" > # TileCache can't use meta-tiling on interlaced PNG files... > FORMATOPTION "interlace=off" > END > > Changed my config to have my OpenLayers pointing directly at Mapserver > 5.0, launch my browser and... Wow, it looks great !!! > > Then, I tried some optimization and I added to my OUTPUTFORMAT element > (as seen in "AGG rendering specifics" howto) : > FORMATOPTION "quantize_force=on" > FORMATOPTION "quantize_dither=off" > FORMATOPTION "quantize_colors=256" > > Well, the line work is still beautiful but I now have 2 problems : > 1) I lost background transparency. My tiles appear with a white > background, I tried to change IMAGECOLOR from 255 255 255 to -1 -1 -1, > also to remove this element but it doesn't change anything. > 2) Fonts and symbols looks very crappy, they are mixed black and white > where they should be filled with black with a white outline. > > On a random tile, the image size fall from 102KB down to 25KB. Such > ratio is not representative at all since it's not an average and it's > only about vector data but still, quantize option seems very interesting > and I don't want to give up because of transparency problems. > > Trying to solve the first problem, I found a workaround for the second. > When I set the TRANSPARENT parameter of the WMS request to 'false' (or > any value different of 'true'), then fonts and symbols are displayed > normally. It could have been ok if TRANSPARENT was not an optional > parameter... The map should looks good in the default case. > > Does someone could give more explanation about the quantize option, > especially regarding transparency management ? > > If possible, a broader answer about the FORMATOPTION element would help > a lot. Indeed, it seems like most optimizations are possible through > output format tuning. Unfortunately, I have not been able to find any > reference document on this... > > Regards, > > -- > Gilles Bassiere > MAKINA CORPUS > 30 rue des Jeuneurs > FR-75011 PARIS > http://www.makina-corpus.com >
