bugGNU Octave - Bugs: bug #51444, surf(): additional white lines in...

 
 

bug #51444: surf(): additional white lines in surface plot

Submitted by:  Hartmut <hardy>
Submitted on:  Tue 11 Jul 2017 05:49:53 PM UTC  
 
Category: Plotting with OpenGLSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Inaccurate Result
Status: ConfirmedAssigned to: None
Originator Name: Open/Closed: Open
Release: 4.2.1Operating System: Any

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Fri 14 Jul 2017 01:27:17 AM UTC, comment #3:

The white lines are simply the axes color showing through. You can check that by setting the axes background color to something vivid. Assuming the sample code from comment #2 has been executed, try

This might be an Octave problem, but it's not an obvious one. The lines appear to be where OpenGL has broken surfaces into triangles when tessellating the surface. In particular, a square gets broken in to two triangles which "overlap" along the diagonal of the square. I think someone who is a real OpenGL expert needs to review libinter/corefcn/gl-render.cc.

Rik <rik5>
Project Administrator
Tue 11 Jul 2017 07:43:46 PM UTC, comment #2:

I have compiled the current dev version of Octave (hg id b85a46745298 of today) on my Linux system:

  • I can confirm Dmitri's observation that the demo code in comment #0 does NOT have those white lines any more.
  • BUT when I use my mouse to rotate this 3d plot, then I DO see those white lines come back, quite often.

A demo script to reproduce those white lines in current dev Octave is this (just a changed view command):

I will attach a screenshot of this tilted 3d plot with current dev Octave (under Linux).

(file #41172)

Hartmut <hardy>
Tue 11 Jul 2017 05:57:19 PM UTC, comment #1:

That seems to be fixed in dev version.

Dmitri.
--

(file #41171)

Dmitri A. Sergatskov <dasergatskov>
Tue 11 Jul 2017 05:49:53 PM UTC, original submission:

This happens with Octave 4.2.1 and the OpenGL toolkits . Here is how to reproduce it:

In the resulting (2d view on a) 3d surface plot, there are some additonal white lines visible. (They are also visible in other 3d view orientations.) Those white lines should not be there.

I have observed this with Windows 7 as well as with Ubuntu 16.04 linux.

The generated 3d plot of Matlab does not show those white lines. But I think this is not only a compatibility issue, but an Octave plotting bug on its own. Those white lines simply shouldn't be there, they spoil the appearance of the whole 3d plot.

I will attach 3 screenshots from Octave results (under Win7 and Ubuntu 16.04) as well as Matlab results (Win7).

Hartmut <hardy>

 

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Attached Files
file #41169:  Screenshot_Octave_Win7.jpg added by hardy (87KiB - image/jpeg)
file #41170:  Screenshot_Matlab_Win7.jpg added by hardy (95KiB - image/jpeg)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -unavailable- added by rik5 (Posted a comment)
  • -unavailable- added by dasergatskov (Updated the item)
  • -unavailable- added by hardy (Submitted the item)
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    Follow 6 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Fri 14 Jul 2017 01:27:17 AM UTCrik5StatusNone=>Confirmed
    Tue 11 Jul 2017 07:43:46 PM UTChardyAttached File-=>Added Screenshot_Octave-dev_Linux_(rotated).png, #41172
    Tue 11 Jul 2017 05:57:19 PM UTCdasergatskovAttached File-=>Added 3e93a2a66cdf+_qt.png, #41171
    Tue 11 Jul 2017 05:49:53 PM UTChardyAttached File-=>Added Screenshot_Octave_Linux.png, #41168
      Attached File-=>Added Screenshot_Octave_Win7.jpg, #41169
      Attached File-=>Added Screenshot_Matlab_Win7.jpg, #41170

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