Thank you for your reply Michael. Is it possible to make the lines in the contourf plot completely transparent using an alpha setting? That would make a reasonable workaround as I intend to overlay black contours anyway.
I've had a look at the source but it is way beyond me; I am a mere dabbler. Cheers, Pete. Michael Droettboom-3 wrote: > > This is a known issue with the contouring code. It's borrowed from an > earlier plotting package called GIST, and assumes that the renderer can > not handle compound polygons (for example, donut-shaped, with both an > inner and outer edge). So instead, it draws "cuts" that go from the > inner to the outer edge. When anti-aliasing is turned on, there is a > slight overlap or "drawing twice" along this edge which creates what > looks like a line. Unfortunately, this can't be remedied by plotting > the contour fills and then plotting the contour edges over top (as is > done is contourf_demo.py). > > As of matplotlib 0.98.x, matplotlib itself can handle compound paths, so > we no longer need the cuts. I've made a few attempts at updating the > contouring code to avoid them, but got nowhere. The contouring code is > very opaque, almost magical code, and most who've dared to go in have > barely made it out alive... ;) That said, a fresh pair of eyes may have > what it takes... > > As for a workaround, you could render your contour as opaque, save that > out as an image and read it back in. The code to do that won't be > pretty, but it just might work. > > Cheers, > Mike > > kippertoffee wrote: >> Hello, >> >> I am attempting to overlay a filled contour over a custom image. >> >> I have managed to get something basic working, but i have encountered a >> problem: >> >> When the contourf plot is set to semi-transparent there are visible lines >> joining the bottom of the plot and the filled contour edges. I have >> attached >> an image of the plot. >> >> http://img232.imageshack.us/my.php?image=spambs6.png spam.png >> >> The code i have used is below; please bear in mind I am not a programmer, >> so >> if the code seems botched, that's because it is. >> >> ############################### >> >> import matplotlib.pyplot as plt >> from pylab import * >> try: >> import Image >> except ImportError, exc: >> raise SystemExit("PIL must be installed to run this example") >> >> lena = Image.open('lena.jpg') >> dpi = rcParams['figure.dpi'] >> figsize = lena.size[0]/dpi, lena.size[1]/dpi >> >> fig = plt.figure(figsize=figsize) >> #fig.patch.set_alpha(0.5) >> ax = fig.add_subplot(111) >> #ax.patch.set_alpha(0.5) >> >> ax.imshow(lena, origin='lower') >> >> ax.contourf(z2,[10,15,20,25,30,35,40,45,50,55,60,65],alpha=0.7) >> show() >> ############################ >> >> >> Can anyone help me with this problem? >> >> Thanks for reading, >> Pete. > > > -- View this message in context: http://www.nabble.com/Filled-contour-transparency-issue-tp18850187p18856313.html Sent from the matplotlib - users mailing list archive at Nabble.com. ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
