How can I make contour lines smoother?

How can I make contour lines smoother?

Answer 1

[Kelly Kearney]

The easiest way to do this is to interpolate your data to a higher resolution using an interpolation scheme that will result in smoother transitions between points, such as a spline.

 [x,y,z] = peaks(10);
 [xnew, ynew] = meshgrid(linspace(-3,3,100));
 znew = interp2(x,y,z,xnew,ynew, 'spline');

 subplot(2,1,1);
 hold on;
 scatter(x(:), y(:), [], z(:), 'filled');
 contour(x,y,z, -6:7);
 subplot(2,1,2);
 hold on;
 scatter(x(:), y(:), [], z(:), 'filled');
 contour(xnew, ynew, znew, -6:7);

Be careful with this, though, since it might introduce some artifacts. Even though it may not be as visually pleasing, the low-res, less-smooth version is a more accurate depiction of the underlying data.

[Konstantin]

Thanks. Very useful example.

Answer 2

[Andrew Reibold]

Is it something you can try "binning"?

[Sandy]

Well the data has already been binned (hist3()).

Answer 3

[Image Analyst]

Please post an image or screenshot. For example, one way could be to blur your image with conv2() or imfilter() before you call contour().