Plotting an irregular closed 3D surface

Hello!

First of all, I am thankful for all the advice 'MATLAB Answers' has given me in the past year. It has helped me in my current problem, but not fully, so I would be very appreciative of any ideas.

I am trying to render a visualization of a closed surface in spherical coordinates. This surface is not necessarily regular and therefore I had to define it piecewise rather than by predefined MATLAB functions. This resulted in a matrix whose elements are radial distances, R(i,j), where i and j are indexed theta and phi values from 0 to 2pi each.

When I try to plot R(i,j), I do not see the object I expect, though I am fairly sure R(i,j) is defined correctly. May you please take a look at my approach and tell me if there is something peculiar about it? Thanks!

My code is:

spacing = 2*pi/N;
Th = 0: 2*pi/spacing : 2*pi;
Phi = 0: 2*pi/spacing : 2*pi;

for (i,j such that R is on the first definition of the piecewise function)
   assign R(i,j) = ...
end

for (i,j such that R is on the second portion)
   assign R(i,j) = ...
end
% etc.

% Then create mesh
[Th_mesh, Phi_mesh] = meshgrid(Th, Phi);

% Convert to cartesian co-ordinates
[X,Y,Z] = sph2cart(Th_mesh, Phi_mesh, R(:,:));

% plot surface
mesh(X,Y,Z)

mesh(X,Y,Z) does not give me the shape I expect. Could it be possible that a problem arises due to how my surface includes planes parallel to the Y-Z plane, thus mapping an x-y coordinate to multiple z values?

Thanks once again for your input.

Regards,

[Yoav Livneh]

Could it be that you meant 2*pi*spacing in the definition of Th and Phi?

[Fangjun Jiang]

It should be: Th=0:spacing:2*pi