surf() plots weird black lines

Hi,

the surface plot contains weird lines that connect edges of the surface. For example the following code:

x = -3:0.1:3;
y = -3:0.1:3;
[xx,yy] = meshgrid(x,y);
zz = xx.^2 - yy.^2;
surf(xx,yy,zz);

plots this:

surprisingly when I File->Save As, those lines are gone from the output image file.

I'm using version: 8.2.0.701 (R2013b) Is this a bug? There appears to be a similar question here: http://www.mathworks.com/matlabcentral/answers/52846-surf-command-gives-false-lines

I know I can disable lines with: 'EdgeColor', none. But I want the grid because it helps me visualize.

Answer 1

[Sean de Wolski]

Most likely opengl and when you print it implicitly changes the renderer to painters. You can do this explicitly by running:

set(gcf,'Renderer','painters')

You could also try using the software version of opengl:

opengl software

[Jason]

Awesome. This was driving me crazy as well. Thanks!

As an FYI 'painters' really slows down the rendering 'zbuffer' seems to work as well and provides faster processing.

Answer 2

[Joseph Cheng]

If you rotate the surf image does the lines disappear? I was able to run what you have in the same 8.2.0.701 (R2013b) (64 bit) and i don't have those lines.

if you check out this thread http://www.mathworks.com/matlabcentral/answers/52943-mesh-or-surf-display-problem-on-windows-7 it does sound like it may be your graphics drivers or openGL.

Answer 3

[Donald K]

The lines remain when you rotate the figure.

Changing OpenGL to software mode does "fix" the issue. Although I have fairly recent NVIDIA drivers - 335.23 - and I don't get these issues with any of the OpenGL code I write. I still think it's a Matlab bug, but at least I have a workaround.

Thank you.

[Sean de Wolski]

The fact that opengl software fixes it points to this not being a MATLAB bug but being a bug in the drivers.