How to obtain an intensity matrix from a surface object?

Hi,

I've sliced a set of volumetric data (V) using the function sl = slice(V,xslice,yslice,zslice).

I end up with a surface object like the one in the image. I need to get a 2D matrix that matches in size the area of my surface and has value 0 where the surface is dark and value 1 where the surface is yellow. In practice, i need to map the position of the yellow circles by having the coordinates of every yellow pixel. Can you please help me?

Answer 1

[Mehmed Saad]

This might work for your case (it is not necessary that this works for every condition)

[X,Y,Z] = meshgrid(-2:.2:2);
V = X.*exp(-X.^2-Y.^2-Z.^2);
xslice = [];   
yslice = [];
zslice = 1;
h= slice(X,Y,Z,V,xslice,yslice,zslice);

mat_2d = h.CData;
figure,surf(mat_2d)

[wals]

Thanks for your help! Unfortunately I've tried that, and for some reason I always end up with an empty array, as if CData only contained zeros.. I'm attaching the slice i get, maybe looking at it direcly helps finding a solution

Answer 2

[Ameer Hamza]

Try this. It extracts color value from the surface and find the center of each circle, using the functions from image processing toolbox.

load('sl.mat');

im = sl(3).CData;
im = imbinarize(im);
reg = regionprops(im);
centers = reshape([reg.Centroid], 2, [])';
x_center = centers(:,1);
y_center = centers(:,2);

figure;
imshow(im);
hold on;
plot(x_center, y_center, 'r+');