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

Havard Tveite havard.tveite at umb.no
Thu Jan 14 06:52:17 EST 2010

```Oliver Christen wrote:
> mmm, then whats the difference between "points 1 1 end" and "points 8 8 end"
> ?

For an ELLIPSE symbol definition without GAP, there is no
difference.
The bounding box of the symbol will be used when rendering
the symbol.  The height of the symbol bounding box on the
map will be the size given in the STYLE of the CLASS in
the LAYER.
I have found this practice very convenient when creating
complex vector symbols.

When you have an ELLIPSE symbol definition with a GAP
specified, the relationship between the values used in
POINTS and GAP is very important.

For the current version of Mapserver and AGG, if you set
SIZE in STYLE to 8, and combine that with the symbol
definition I suggested (points 8 8, gap 24), I think you
would get a reasonable result.

Håvard

>> 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 ?
>> The size of the symbols are determined by the values given
>> in the style of the class in the layer.  So the magnitude
>> of the values used in the symbol definition only have
>> effect within the symbol definition (makes it possible to
>> use only integers, and makes it easier to do the
>> arithmetics :-) ).
>> The magnitude of the values used in the symbol definition
>> should have no bearing on the way the symbols are rendered
>> by Mapserver.
>>
>> Håvard
>>
>>> 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.bonfort at gmail.com
>>>>> <mailto:thomas.bonfort at gmail.com>>
>>>>>
>>>>>     gap in pixels = symbol->gap * style->size
>>>>>
>>>>>
>>>>>     On Tue, Jan 12, 2010 at 16:52, Oliver Christen
>>>>>     <oliver.christen at camptocamp.com
>>>>>     <mailto:oliver.christen at 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.bonfort at gmail.com>
>>>>>             *To:* Oliver Christen
>>>>> <mailto:oliver.christen at camptocamp.com>
>>>>>             *Cc:* mapserver-users at lists.osgeo.org
>>>>>             <mailto:mapserver-users at 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.christen at camptocamp.com
>>>>>             <mailto:oliver.christen at camptocamp.com>> wrote:
>>>>>
>>>>>                 Hi Thomas :)
>>>>> 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.bonfort at gmail.com>
>>>>>                     *To:* Oliver Christen
>>>>>                     <mailto:oliver.christen at camptocamp.com>
>>>>>                     *Cc:* mapserver-users at lists.osgeo.org
>>>>>                     <mailto:mapserver-users at 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.christen at camptocamp.com
>>>>>                     <mailto:oliver.christen at 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
>>>>>                         _______________________________________________
>>>>>                         mapserver-users mailing list
>>>>>                         mapserver-users at lists.osgeo.org
>>>>>                         <mailto:mapserver-users at lists.osgeo.org>
>>>>>
>>>>> http://lists.osgeo.org/mailman/listinfo/mapserver-users
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>> --
>>>> 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/
>>>>
>>>
>> --
>> 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/
>>
>
>

--
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/
```