CODEWITHSUNDEEP
matlabimage-processing
anonymous
anonymous

Reputation: 188

Find Overlapping Region between 3-Dimensional Shapes

I'm currently plotting 2 separate 3-dimensional amorphous blobs which overlap each other. I have created the blobs by deforming a unit circle (as you can see in the code provided below). My question is: is there an easy way to isolate the overlapping region? I need to isolate the overlapping region and then color it differently (as in turn the region green, for example) to clearly show where the overlap is. My actual program has many shapes that overlap, however for the sake of simplicity, i have produced the following code to illustrate what i am trying to do:

% Create Sphere with 100 points
N = 100;                 % sphere grid points
[X,Y,Z] = sphere(N);     % get x,y,z coordinates for sphere
num=size(X,1)*size(X,2); % get total amount of x-coordinates (m*n)

% Loop through every x-coordinate and apply scaling if applicable
for k=1:num              % loop through every coordinate
   value=X(k);           % store original value of X(k) as value
   if value<0            % compare value to 0
      X(k)=0.3*value;    % if < 0, scale value
   end
end

% Loop through every z-coordinate and apply scaling if applicable
for k=1:num              % loop through every coordinate
   value=Z(k);           % store original value of X(k) as value
   if value>0            % compare value to 0
      Z(k)=0.3*value;    % if < 0, scale value
   end
end

mesh(X,Y,Z,'facecolor','y','edgecolor','y','facealpha',...
    0.2,'edgealpha',0.2); 
hold on
mesh(-1*(X-1),Y,Z,'facecolor','r','edgecolor','r','facealpha',...
    0.2,'edgealpha',0.2); 
hold off
axis equal

I'm not necessarliy looking for code, just an effective algorithm or process to achieve the desired results as I need to adapt this result into the more sophisticated program I have.

Upvotes: 0

Views: 1492

Answers (2)

Paul Paulsen
Paul Paulsen

Reputation: 355

I have worked in 2D with the MATLAB builtin function inpolygon to find out overlapping areas. However, it does not natively support 3d. I would suggest you try the inhull function which you can find here at file exchange. Please note it only supports convex hulls.

If that doesn´t help you maybe you find some inspiration in this discussion.

Upvotes: 0

Paul Stearns
Paul Stearns

Reputation: 906

Maintain an array (n-dimensional) of integers, as you draw your objects, increment each corresponding point in the array. When done, loop through the array, and each element > 1 has an overlap between two or more objects, use the array coordinate to color the objects based on the number of overlaps.

Upvotes: 1

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