[Octave-bug-tracker] [bug #48387] Wrong line joins make noisy data much noisier

[ederag]

URL:
  <http://savannah.gnu.org/bugs/?48387>

                 Summary: Wrong line joins make noisy data much noisier
                 Project: GNU Octave
            Submitted by: ederag
            Submitted on: Sun 03 Jul 2016 10:58:13 AM GMT
                Category: Plotting with OpenGL
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

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Details:

Sometimes printed plots look much noisier than they should, with Qt backend.

The files given have been obtained with the latest development version. 

hg id  -in
91611c9e1d81 22032

The attached `script_miter.m` loads an experimental data file, plot and print
it.

On screen (qt_screenshot.png) the plot looks fine, with little noise.
The printout (qt_try.png) is much noisier, to the point that the qt backend
can not be used for reporting purposes.

with graphics_toolkit("gnuplot"), the printout is fine (except for the color):
gnuplot_try.png.

At first sight, this seems related to bug #46529, but here the spacing is
reasonable (2048 points, minimum dx > 0.5).
Decimating is not an option here.

It might be related to line joins:
http://ngwww.ucar.edu/gks/ps.html#MiterLimit




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File Attachments:


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Date: Sun 03 Jul 2016 10:58:13 AM GMT  Name: script_miter.m  Size: 250B   By:
ederag

<http://savannah.gnu.org/bugs/download.php?file_id=37677>
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Date: Sun 03 Jul 2016 10:58:13 AM GMT  Name: qt_try.png  Size: 21kB   By:
ederag

<http://savannah.gnu.org/bugs/download.php?file_id=37678>
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Date: Sun 03 Jul 2016 10:58:13 AM GMT  Name: qt_screenshot.png  Size: 33kB  
By: ederag

<http://savannah.gnu.org/bugs/download.php?file_id=37679>
-------------------------------------------------------
Date: Sun 03 Jul 2016 10:58:13 AM GMT  Name: gnuplot_try.png  Size: 22kB   By:
ederag

<http://savannah.gnu.org/bugs/download.php?file_id=37680>

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