[mapserver-users] Draw roads WITHOUT anti-aliasing

Wed Oct 18 05:55:19 PDT 2017

Hi Lars,

I had not tried that myself but did some tests now. I do not really see any difference in the output  with any values of gamma. Perhaps it is broken.

I have been thinking that one of the most common use cases is to draw adjacent polygons with just fill but no outlines so that the whole area gets unique color even when the fill has some transparency set in STYLE with somehow like

     CLASS
        NAME "polygon_test"
        STYLE
        COLOR 100 50 0
        OPACITY 50
        END
     END

I am not sure if this test makes sense and I know that I can get rid of the borders between the polygons by using COMPOSITE-OPACITY at the LAYER level.

When GD renderer was removed the support to render without anti-aliasing was recognized as a good feature http://mapserver.org/development/rfc/ms-rfc-99.html
-Jukka Rahkonen-

Lähettäjä: mapserver-users [mailto:mapserver-users-bounces at lists.osgeo.org] Puolesta lars.schylberg at blixtmail.se
Lähetetty: 18. lokakuuta 2017 15:05
Vastaanottaja: mapserver-users at lists.osgeo.org
Aihe: Re: [mapserver-users] Draw roads WITHOUT anti-aliasing

Hi,

I did some quick tests with :

  OUTPUTFORMAT
    NAME "png_G0"
    DRIVER AGG/PNG
    MIMETYPE "image/png"
    IMAGEMODE RGB
    EXTENSION "png"
    FORMATOPTION "GAMMA=0.0"
  END

and shp2img with options -i

eg: shp2img -m 01_polygon_td_poly.map -o 01_polygon_td_poly.png -i png_G0

I did some tests with both polygons, polygon outlines and lines and they all seems to have anti-aliasing as far as I could see.

Would this be an ok way to test it?  I also have some people that would like to do lines without anti-aliasing for a strange reason.

Lars Schylberg

-----Originalmeddelande-----
> Från: "Rahkonen Jukka (MML)" <jukka.rahkonen at maanmittauslaitos.fi<mailto:jukka.rahkonen at maanmittauslaitos.fi>>
> Till: "Eichner, Andreas - SID" <Andreas.Eichner at sid.sachsen.de<mailto:Andreas.Eichner at sid.sachsen.de>>, "Erik H" <erik.h11.01 at gmail.com<mailto:erik.h11.01 at gmail.com>>
> Kopia: mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>
> Datum: 2017-10-18 11:13
> Ämne: Re: [mapserver-users] Draw roads WITHOUT anti-aliasing
>
> Hi,
>
> I suppose that the amount of antialiasing with AGG is set with "gamma" parameter.  Mapserver supports that at least for polygons as documented in http://www.mapserver.org/mapfile/outputformat.html but you could try if using gamma=0.0 has an effect on lines as well. It may be that it does not because search
> https://github.com/mapserver/mapserver/search?utf8=%E2%9C%93&q=gamma&type=
> seems to find only something that is tied to polygon outlines
> https://github.com/mapserver/mapserver/blob/branch-7-0/renderers/agg/include/agg_renderer_outline_aa.h
>
>
> If gamma does not work for lines then it could be worth making a feature request for adding a new formatoption "GAMMA_LINE=[].
>
> Couple of Mapnik links dealing with the same issue:
> http://gis.19327.n8.nabble.com/Turning-off-anti-aliasing-td5339458.html
> http://mapnik.org/mapnik-reference/#3.0.6/line-gamma-method
>
> -Jukka Rahkonen-
>
>
>
> -----Alkuperäinen viesti-----
> Lähettäjä: mapserver-users [mailto:mapserver-users-bounces at lists.osgeo.org<mailto:mapserver-users-bounces at lists.osgeo.org>] Puolesta Eichner, Andreas - SID
> Lähetetty: 18. lokakuuta 2017 9:57
> Vastaanottaja: Erik H <erik.h11.01 at gmail.com<mailto:erik.h11.01 at gmail.com>>
> Kopio: mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>
> Aihe: Re: [mapserver-users] Draw roads WITHOUT anti-aliasing
>
> Damn... missed attaching the images.
>
> > -----Ursprüngliche Nachricht-----
> > Von: mapserver-users [mailto:mapserver-users-bounces at lists.osgeo.org<mailto:mapserver-users-bounces at lists.osgeo.org>]
> > Im Auftrag von Eichner, Andreas - SID
> > Gesendet: Mittwoch, 18. Oktober 2017 08:28
> > An: Erik H
> > Cc: mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>
> > Betreff: Re: [mapserver-users] Draw roads WITHOUT anti-aliasing
> >
> > Hi,
> >
> > I just meant that it seems to be pretty easy to implement aliased
> > rendering with AGG.
> > Simply 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;
> >
> > turns of anti-aliased rendering. I've attached the output of "shp2img
> > -m line_simple.map" from the msautotests.
> > An additional member in class AGG2Renderer for the aliased rasterizer
> > and conditionally passing one or the other to render_scanlines()
> > depending on some value of strokeStyleObj might be enough.
> >
> > Regards
> >
> > > -----Ursprüngliche Nachricht-----
> > > Von: Erik H [mailto:erik.h11.01 at gmail.com<mailto:erik.h11.01 at gmail.com>]
> > > Gesendet: Dienstag, 17. Oktober 2017 17:34
> > > An: Eichner, Andreas - SID
> > > Cc: Richard Greenwood; mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>
> > > Betreff: Re: [mapserver-users] Draw roads WITHOUT anti-aliasing
> > >
> > > As for Andreas' remark about 'simply the use of another scanline
> > > rasterizer.' - I'm sorry but I'm not much of a C++ developer. If I
> > have
> > > to do rasterizing, I'd skip MapServer altogether and generate the
> > > PNG
> > in
> > > Java.
> > >
> > _______________________________________________
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> > mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org>
> > https://lists.osgeo.org/mailman/listinfo/mapserver-users
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