Matlab Tensor Visualization

ellipsoid_discs_plot.m

function [hmame, hmami] = Ellipsoid_discs_plot(vma, vme, vmi)
%Ellipsoid_discs_plot plots an ellipsoid as two
%elliptical discs.
%
%The center of the ellipsoid is assumed to be 0,0,0. The tool has been
%designed to visualize tensorial properties using the characteristic
%Eigenvectors. Using cross-section elliptical discs to visualize ellipsoids
%may provide improved visualization compared to volumetric ellipsoids.
%
% Parameters
% vma - Eigenvector correspoding to maximum Eigenvalue
% vme - Eigenvector correspoding to intermediate Eigenvalue
% vme - Eigenvector correspoding to minimum Eigenvalue
%
% Returns
% [hmame, hmami] - Graphics handles to discs for max-med and max-min, 
% respectively (Matlab's fill3)
vmajor = vma;
vminors = {vme,vmi};
hs = cell(2);
for i = 1:2
    vminor = vminors{i};

    % theta for parametric representation of ellipse
    theta = linspace(0,2*pi,50);

    % points on ellipse from parametric form
     X = cos(theta)*vmajor(1) + sin(theta)*vminor(1);
     Y = cos(theta)*vmajor(2) + sin(theta)*vminor(2);
     Z = cos(theta)*vmajor(3) + sin(theta)*vminor(3);
    
    % 3D filled polygon, color and alpha can be changed using handles
    gr = 0.6;
    hms = fill3(X,Y,Z,[gr,gr,gr]);
    set(hms, 'FaceAlpha', 0.7);
    hold on;
    hs{i} = hms;
end
hmame = hs{1};
hmami = hs{2};
end