How to use function "scatter3(y)" to show the image of a 3D matrix?
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I want to use Matlab to show the image of a 3D matrix made up of 1 and 0. For example, a 3*3*3 matrix named testy, and
testy(:,:,1)=[1,1,0;0,0,0;0,0,0];
testy(:,:,2)=[0,0,0;1,1,0;0,0,0];
testy(:,:,3)=[0,0,0;0,0,0;1,1,0];
I know that function "spy(y)" is used to show the image of 2D matrx, and I find it's easy to use. But I didn't get much from the help document about scatter3, especially, I'm confused about the example of sphere and the format of X,Y,Z.
Any suggestion will be helpful,and thank you very much.
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Accepted Answer
Jacob Halbrooks
on 8 Mar 2012
SCATTER3 takes its data as vectors and interprets them as the locations to place circles. In the help example for SCATTER3, the X,Y, and Z matrices returned by SPHERE are indexed with : to convert them to vectors. For your example, this might looks like:
testy(:,:,1)=[1,1,0;0,0,0;0,0,0];
testy(:,:,2)=[0,0,0;1,1,0;0,0,0];
testy(:,:,3)=[0,0,0;0,0,0;1,1,0];
Xmatrix = testy(:,:,1);
Ymatrix = testy(:,:,2);
Zmatrix = testy(:,:,3);
scatter3(Xmatrix(:), Ymatrix(:), Zmatrix(:));
However, based on your mention of SPY, I suspect that you are not interested in the plot above but instead in seeing the (x,y,z) locations of each 1 plotted. If this is the case, it might be helpful to use IND2SUB with FIND to get the coordinates of each 1 and then plot this with SCATTER3:
[rowInd,colInd,zInd]=ind2sub(size(testy),find(testy));
scatter3(colInd, rowInd, zInd);
The resultant scatter plot is similar to stacking SPY plots of each matrix sheet.
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