Re: [mapserver-users] symbol circle (ellipse) rendered not round but oval

[Oliver Christen]

mmm, in my opinion it would be clearer if the GAP didnt depend from 
anything, set the GAP to 10 would make you a spacing of 10px between each 
symbols border, whatever the values of the symbol POINTS.
but that may be a change too important ?

Oliver
Stephen Woodbridge wrote:
So if I want ten pixel ellipses with a 1, 2, or 3 pixels gap how would 
you specify that?

points 10 10 gap 1 (or 2 or 3)?

Yes, if the rendering behaviour had been according to my
preferences,
POINTS 10 10 END
GAP 1 (or 2 or 3)
should do it (if you had specified SIZE 10 in the STYLE).
You specify the gap, and not the centre to centre distance
between the ellipses.

But currently, this is not the behaviour.
Currently (with AGG in 5.6.0) you would have to specify:
POINTS 10 10 END
GAP 6 (or 7 or 8)
to get something close (if you specify SIZE 10 in the STYLE).

Something seems to be wrong when the GAP is close to
half the diameter specified in POINTS - some of the gaps
will be as expected, while others are larger (closer to the
actual number specified in GAP).

Håvard


-Steve W

Havard Tveite wrote:
If Thomas B. agrees, I think it would be reasonable to also
open a bug on the gap calculation.
In my opinion, since the word "gap" is used, the correct
way to specify a symbol with ellipses that has the same
gap between them as the diameter of the ellipses should be
as follows:

symbol
  name dots
  type ellipse
  points 1 1 end
  gap 1
end

or an equivalent "scaled" version such as:

symbol
  name dots
  type ellipse
  points 23 23 end
  gap 23
end

The actual size of the ellipses (and the width of the gaps)
should be determined by the SIZE in CLASS-> STYLE.  If
SIZE is 10, the ellipses should have a 10 pixel diameter
(and should have a 10 pixel gap between them).

I have been hesitant to file bugs regarding symbology, since
the documentation on symbology is lacking and there is not
complete agreement on how some of the things that has to do
with symbology should work.  There have also been
discussions on changing some behaviour and mechanisms for
symbology.
First we have to agree on how things should work and document
it, then we can file bugs if behaviour is not as expected.

Håvard

Oliver Christen wrote:
Hi Steve

I followed your suggestion and opened a documentation bug

thanks
Oliver

Hi guys,

I haven't followed this whole thread but I think it should be better 
documented so people can understand how to use this. Please write a 
doc bug and put as much information in the bug about how this works as 
you have been able to discover.

Thanks,
  -Steve W

Oliver Christen wrote:
Thank you Håvard
I see you have changed "points 1 1 end" by "points 8 8 end".
Tell me if im wrong, but these values are only used to render the 
proportions of the elipse but not it's size, is that correct?
so if I understand correctly, using larger values for the elipse 
width/height refine the rendering of the vectorised dot geometry ?

regards
Oliver

Dear Oliver Christen,

Using Mapserver 5.6.0 and AGG rendering, you can achieve what
you want by using a combination of ellipse size and gap size
in the symbol definition.
There is something strange in the calculations (a gap of
about half the ellipse size seems to produce touching symbols),
so in your case, you could try to use 8 as the diameter of the
ellipses, and 20 + 4 (half the ellipse size) = 24 as the
gap:

symbol
 name dots
 type ellipse
 points 8 8 end
 gap 24
end


Håvard

Oliver Christen wrote:
thank you Thomas

so if I have a dot of, for example, 8px and I want a space pf 20px 
between the dots, I need a gap of 20/8 =  2.5

but as far as I can see, Mapserver doesnt like none-integer value 
for gap.

what should I do? :(

2010/1/12 thomas bonfort <thomas.bonf...@gmail.com 
<mailto:thomas.bonf...@gmail.com>>

    gap in pixels = symbol->gap * style->size


    On Tue, Jan 12, 2010 at 16:52, Oliver Christen
    <oliver.chris...@camptocamp.com
    <mailto:oliver.chris...@camptocamp.com>> wrote:

        GAP 20 is really giving unwanted result:
         http://dev.camptocamp.com/~ochriste/tilecache9.png
        <http://dev.camptocamp.com/%7Eochriste/tilecache9.png>
         though using only one style instead of two seems to solve 
the
        oval problem (but why ???)
         style
             symbol "dots"
             size 8
             color 204 102 0
             outlinecolor  102 51 0
            end
         I dont understand how GAP is supposed working:
         with GAP 2, I had ~10px between dots,
        with GAP 3, I had ~18px between dots,
        with GAP 4, I had ~26px between dots
         whats the logic ?

            ----- Original Message -----
            *From:* thomas bonfort 
<mailto:thomas.bonf...@gmail.com>
            *To:* Oliver Christen 
<mailto:oliver.chris...@camptocamp.com>
            *Cc:* mapserver-users@lists.osgeo.org
            <mailto:mapserver-users@lists.osgeo.org>
            *Sent:* Tuesday, January 12, 2010 4:36 PM
            *Subject:* Re: [mapserver-users] symbol circle 
(ellipse)
            rendered not round but oval

            symbol
             name dots
             type ellipse
             points 1 1 end
             gap 20
            end

            ...

            style
             symbol "dots"
             size 8
             color r g b
             outlinecolor  r g b
            end




            On Tue, Jan 12, 2010 at 16:31, Oliver Christen
            <oliver.chris...@camptocamp.com
            <mailto:oliver.chris...@camptocamp.com>> wrote:

                Hi Thomas :)
                 thanks for the answer, but sadely it didnt solve 
my problem:
                 here are a few tests I did:
                 using GAP 20 gave me really weird result:

http://dev.camptocamp.com/~ochriste/tilecache6_gap_20.png

<http://dev.camptocamp.com/%7Eochriste/tilecache6_gap_20.png>
                 using PATTERN 1 22 END gave me better result, but 
the
                dot are still slightly oval:

http://dev.camptocamp.com/~ochriste/tilecache7_pattern.png

<http://dev.camptocamp.com/%7Eochriste/tilecache7_pattern.png>
                 I wondered if the visual effect may have come from 
the
                fact im pilling up two circle one over the other, 
but
                even when trying to display only the outer or inner
                circles, the circle are still slightly off:

http://dev.camptocamp.com/~ochriste/tilecache4_outercircle.png

<http://dev.camptocamp.com/%7Eochriste/tilecache4_outercircle.png>

http://dev.camptocamp.com/~ochriste/tilecache5_innercircle.png

<http://dev.camptocamp.com/%7Eochriste/tilecache5_innercircle.png>
                (both at once

http://dev.camptocamp.com/~ochriste/tilecache3_bothcircle.png

<http://dev.camptocamp.com/%7Eochriste/tilecache3_bothcircle.png>)
                 any other idea? ^_^

                    ----- Original Message -----
                    *From:* thomas bonfort
                    <mailto:thomas.bonf...@gmail.com>
                    *To:* Oliver Christen
                    <mailto:oliver.chris...@camptocamp.com>
                    *Cc:* mapserver-users@lists.osgeo.org
                    <mailto:mapserver-users@lists.osgeo.org>
                    *Sent:* Tuesday, January 12, 2010 3:18 PM
                    *Subject:* Re: [mapserver-users] symbol circle
                    (ellipse) rendered not round but oval

                    hi Oliver :)

                    try with GAP 20 instead of STYLE 1 20 END 
(which is
                    deprecated btw, use PATTERN now)

                    cheers,
                    thomas

                    On Tue, Jan 12, 2010 at 15:04, Oliver Christen
                    <oliver.chris...@camptocamp.com
                    <mailto:oliver.chris...@camptocamp.com>> wrote:

                        hello

                        I have a weird problem with symbology.
                        Im rendering a line with dots, but the dots 
are
                        not round but slightly oval, see image

http://dev.camptocamp.com/~ochriste/tilecache.png

<http://dev.camptocamp.com/%7Eochriste/tilecache.png>

                        Any idea what could be the cause ?

                        Here is my symbol definition:

                        SYMBOL
                         NAME "linie-gepunkt10"
                         TYPE ELLIPSE
                         POINTS
                          1 1
                         END
                         STYLE
                          1 20
                         END
                         FILLED TRUE
                        END

                        and my layer's class definition:

                         CLASS
                          EXPRESSION "3"
                          MAXSCALEDENOM 200001
                          STYLE
                            SYMBOL "linie-gepunkt10"
                            SIZE 10
                            COLOR 102 51 0
                          END
                          STYLE
                            SYMBOL "linie-gepunkt10"
                            SIZE 8
                            COLOR 204 102 0
                          END
                         END

                        and the map outputformat:

                        OUTPUTFORMAT
                         NAME png
                         DRIVER "AGG/PNG"
                         MIMETYPE "image/png"
                         IMAGEMODE RGBA
                         EXTENSION "png"
                         FORMATOPTION "INTERLACE=OFF"
                        END

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--
Håvard Tveite
Department of Mathematical Sciences and Technology, UMB
Drøbakveien 31, POBox 5003, N-1432 Ås, NORWAY
Phone: +47 64965483 Fax: +47 64965401 http://www.umb.no/imt/

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--
Håvard Tveite
Department of Mathematical Sciences and Technology, UMB
Drøbakveien 31, POBox 5003, N-1432 Ås, NORWAY
Phone: +47 64965483 Fax: +47 64965401 http://www.umb.no/imt/


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