Generally speaking, a plottable 3D surface can be represented parametrically in 2D (hence why it is a surface). Your point cloud can not be represented parametrically in 2 dimensions, hence why you are having difficulty figuring out how to plot it as a surface. I used to have similar problems with 3D plotting (both here and in Matlab) before I came to this realization.
Your comment "of course, plotting a sphere can be done in spherical coordinates" is actually the right thought process. Spherical coordinates is how you parametrize your spherical surface. Pick a coordinate system that is relevant to your problem at hand and use it. I hope this helps! Ben Root On Sat, Nov 1, 2014 at 2:07 PM, Peter Kerpedjiev <pkerpedj...@gmail.com> wrote: > Hi, > > I'm trying to plot an outline of an arbitrary 3D shape using > matplotlib's plot_surface, and I wanted to ask if any one has any ideas > as to how to do it. Here's the beginnings of a simple example: > > # create a grid > resolution = 10 > > xs = np.linspace(-1,1,resolution) > ys = np.linspace(-1,1,resolution) > zs = np.linspace(-1,1,resolution) > > X,Y,Z = np.meshgrid(xs, ys, zs) > > #Then we can calculate the square of the distance of each point to the > center: > W = X**2 + Y**2 + Z**2 > > # Let's see which points are within a certain radius: > C = W < 1. > > # this can be used to create a point-cloud > x = X[C] > y = Y[C] > z = Z[C] > > From this I tried a lot options, the best being to do some XOR > operations on the array C to get a list of points which are on the > surface of the sphere. My question is, can anybody see a reasonable way > to plot this surface using mplot3D? > > Of course plotting a sphere can be done using spherical coordinates, but > that defeats the purpose of this example :) This is just a > simplification as the application is actually to draw 3D contours (i.e. > shapes, rather than iso-lines) of a three-parameter probability > distribution. > > Thanks in advance, > > -Peter > > > > > > > > > > > > ------------------------------------------------------------------------------ > _______________________________________________ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-users >
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