AGG and WMS

[Yewondwossen Assefa]

Brent,

  I think what happens is the following : when mapserver gets your wms 
request with FORMAT=png, it selects the the GD PNG 8 bit driver. I am 
not sure right now wms/outputformat should be handled so that this king 
of situation does not happen.
  A quick work around from what I can see would be

   - define an agg output format is your map file :
      OUTPUTFORMAT
     NAME "agg/png24"
     MIMETYPE "image/png; mode=24bit"
     DRIVER "AGG/PNG"
     EXTENSION "png"
   END

  - set you imagetyppe in the map file to be IMAGETYPE agg/png24

  - when doing a wms request use FORMAT=image/png; mode=24bit

  This should ensure that your agg output format is used.

  Best Regards,


Brent Fraser wrote:
> Christopher,
> 
>   Sorry for the terse question, here are some more
> details...
> 
> I'm using the AGG/PNG output driver (see RFC-32) in
> Mapserver 5.0 beta 4 to render shapefile vectors (no raster
> input) to a PNG graphic file.  When I use Mapserver's CGI
> interface to request a graphic map, the lines appear
> anti-aliased (smooth, no jaggies) Great!  But when I use
> Mapserver's WMS interface, I get the same old rendering
> Mapserver always gave (lines with jaggies).
> 
>   Note there was an email
> (http://lists.umn.edu/cgi-bin/wa?A2=ind0703&L=mapserver-dev&
> T=0&O=D&X=639F0B08FDD720FAC9&P=6714) saying "WSM right now
> only advertise gd and gdal based drivers. See bug 455".
> 
> 
>   After some review of the images, it looks like my "DRIVER
> AGG/PNG" produces a 24 bit png file via CGI, but an 8 bit
> png file via WMS.  When I try to do AGG/PNG24, I get
> "General error message. OUTPUTFORMAT clause references
> driver AGG/PNG24, but this driver isn't configured." from
> Mapserver.  I'll have to do some more digging...
> 
> Brent Fraser
> GeoAnalytic Inc.
> Calgary, Alberta
> 
> ----- Original Message ----- 
> From: "Christopher Schmidt" <crschmidt at METACARTA.COM>
> To: <MAPSERVER-USERS at LISTS.UMN.EDU>
> Sent: Thursday, August 23, 2007 1:03 PM
> Subject: Re: [UMN_MAPSERVER-USERS] AGG and WMS
> 
> 
>> On Thu, Aug 23, 2007 at 12:32:41PM -0600, Brent Fraser
> wrote:
>>> Is AGG supposed to do anti-aliased output when Mapserver
> is
>>> used as a WMS server?
>> I'm not sure what 'antialiased' output means -- perhaps
> you mean 'alpha
>> transparency', perhaps you mean antialiasing within the
> images, perhaps
>> you mean something else. Can you clarify?
>>
>> The answer to the first is, I believe,  "no". WMS spec
> only allows for
>> 'transparency or no transparency', and MapServer does not
> implement
>> alpha transparency output in the WMS images.
>>
>> The answer to the second is "Sure" -- the images for
>> http://boston.freemap.in/ are fetched from WMS (by
> TileCache).
>> Regards,
>> -- 
>> Christopher Schmidt
>> MetaCarta
> 


-- 
----------------------------------------------------------------
Assefa Yewondwossen
Software Analyst

Email: assefa at dmsolutions.ca
http://www.dmsolutions.ca/

Phone: (613) 565-5056 (ext 14)
Fax:   (613) 565-0925
----------------------------------------------------------------