GetRandomEllipseImage3D.m

% GetRandomEllipseImage3D(K)
% generate a logical image with K overlapping ellipses
% 

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function [bw,pts]=GetRandomEllipseImage3D(K)

IMSIZE = [200,200,200];
mu = [100,100,100];

bw = false(IMSIZE);

pts = {};
bValidEllipse=0;

while ~bValidEllipse
    for kk=1:K
        pts{kk} = GetRandomEllipsePts(mu);
    end
    
    % place each ellipse
    for kk=2:K
        ptsCombined=vertcat(pts{1:kk-1});
        idxK = 1+round((length(pts{kk})-1)*rand());
        idxCombined = 1+round((length(ptsCombined)-1)*rand());
        offset = ptsCombined(idxCombined,:)-pts{kk}(idxK,:);
        pts{kk} = pts{kk} + repmat(offset,[size(pts{kk},1), 1]);
    end
    idxPts={};
    for kk=1:K
        idxPts{kk}=sub2ind(IMSIZE,pts{kk}(:,1),pts{kk}(:,2),pts{kk}(:,3));
    end
    
    idxPtsOverlap=GetOverlap(idxPts);
    % make sure no ellipse is fully contained in another
    nNonOverlap=idxPtsOverlap(2.^[0:K-1]);
    nNonOverlap=cellfun(@length,nNonOverlap);
    if all(nNonOverlap~=0)
        bValidEllipse=1;