[mapserver-users] differing image size with different mapserver versions

Mon May 17 07:24:20 PDT 2021

Good news.

There seems to be more to fix in the documentation about ANTIALIAS but who understands how it works now in master with lines, polygons, and labels?

-Jukka Rahkonen-

Lähettäjä: Richard Greenwood <richard.greenwood at gmail.com>
Lähetetty: maanantai 17. toukokuuta 2021 17.11
Vastaanottaja: Eichner, Andreas - SID <Andreas.Eichner at sid.sachsen.de>
Kopio: Rahkonen Jukka (MML) <jukka.rahkonen at maanmittauslaitos.fi>; Mapserver-Users (mapserver-users at lists.osgeo.org) <mapserver-users at lists.osgeo.org>
Aihe: Re: [mapserver-users] differing image size with different mapserver versions

Progress! Using Andreas' suggestion:

changing the typedef in line 91 of mapagg.cpp from
  typedef mapserver::renderer_scanline_aa_solid<renderer_base> renderer_scanline;
to
  typedef mapserver::renderer_scanline_bin_solid<renderer_base> renderer_scanline;

My test image went from 127kB down to 23.3kB!

Rich

On Mon, May 17, 2021 at 7:58 AM Eichner, Andreas - SID <Andreas.Eichner at sid.sachsen.de<mailto:Andreas.Eichner at sid.sachsen.de>> wrote:
Hi Jukka,

as a result of the discussion IMO Erik created a patch to be able to switch AGGs anti-aliasing on and off using the ANTIALIAS keyword. This was merged by Even Rouault in https://github.com/MapServer/MapServer/pull/6225
It originally worked IMHO only for lines styles. But GAMMA is __not__ the way to turn anti-aliasing off.

Greets, Andreas

-----Ursprüngliche Nachricht-----
Von: mapserver-users <mapserver-users-bounces at lists.osgeo.org<mailto:mapserver-users-bounces at lists.osgeo.org>> Im Auftrag von Rahkonen Jukka (MML)
Gesendet: Montag, 17. Mai 2021 15:26
An: Rahkonen Jukka (MML) <jukka.rahkonen at maanmittauslaitos.fi<mailto:jukka.rahkonen at maanmittauslaitos.fi>>; Mapserver-Users (mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>) <mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>>
Betreff: Re: [mapserver-users] differing image size with different mapserver versions

Hi,

Here is a long thread about turning off antialias http://osgeo-org.1560.x6.nabble.com/Draw-roads-WITHOUT-anti-aliasing-td5338614.html <http://osgeo-org.1560.x6.nabble.com/Draw-roads-WITHOUT-anti-aliasing-td5338614.html> .

I had the same wrong idea about gamma=0 back then but perhaps gamma=0.01 could work.

-Jukka Rahkonen-

Lähettäjä: mapserver-users <mapserver-users-bounces at lists.osgeo.org<mailto:mapserver-users-bounces at lists.osgeo.org>> Puolesta Rahkonen Jukka (MML)
Lähetetty: maanantai 17. toukokuuta 2021 16.06
Vastaanottaja: Mapserver-Users (mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>) <mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>>
Aihe: Re: [mapserver-users] differing image size with different mapserver versions

Hi,

(Re-sent as edited to mailing list because the body was originally too long.

Are you sure about “I actually found that 6.4 produced small, aliased images with both the GD and AGG drivers”.  Originally the AGG library could only do anti-aliasing and that affected also Mapserver 5 https://lists.osgeo.org/pipermail/mapserver-users/2007-September/025467.html <https://lists.osgeo.org/pipermail/mapserver-users/2007-September/025467.html> .

I guess that Mapnik folks have since that added support for controlling anti-aliasing with gamma setting http://mapnik.org/mapnik-reference/.

I can see that gamma can be used also with Mapserver https://www.mapserver.org/mapfile/outputformat.html

Have a try with gamma=0. However, Even wrote that turning off antialiasing is possible only in master, so perhaps gamma=0 does not work.

The documentation for Mapserver 5 tells that “All ANTIALIAS keywords are now ignored". But the keyword still appears in quite a many places:

https://mapserver.org/search.html?q=antialias

Would it be time to remove them as well as now not useful references to GD renderer (removed by RFC 99 in 2013)?

-Jukka Rahkonen-

Lähettäjä: mapserver-users <mapserver-users-bounces at lists.osgeo.org<mailto:mapserver-users-bounces at lists.osgeo.org> <mailto:mapserver-users-bounces at lists.osgeo.org<mailto:mapserver-users-bounces at lists.osgeo.org>> > Puolesta Richard Greenwood
Lähetetty: maanantai 17. toukokuuta 2021 15.26
Kopio: mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org> <mailto:mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>>
Aihe: Re: [mapserver-users] differing image size with different mapserver versions

Thanks for the suggestions. The consensus seems to be that anti-aliasing is causing the increased size. The documentation here <https://mapserver.org/output/antialias.html>  says "Since version 6.0, MapServer will produce aliased output for the “gd/” drivers, and antialiased output for the “agg/” and “cairo/” ones" and it's also mentioned here <https://lists.osgeo.org/pipermail/mapserver-users/2012-April/072011.html>  in Thomas Bonfort's reply. I actually found that 6.4 produced small, aliased images with both the GD and AGG drivers and regardless of my ANTIALIAS true/false setting.

Would anyone consider re-enabling the ANTIALIAS true/false option?

Thanks,

Rich

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--
Richard W. Greenwood, PLS
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