How to extract the cdata of a 2D surface from 3D surface and save it as a matrix?

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Ke Zhang
Ke Zhang 2022-3-13
评论： Image Analyst 2022-3-14
Hello, I generated a 3D surface. The task is to extract the cdata of a 2D surface from the 3D surface and save it as png files. For example, extract the surface (0,90). I attached the X and Y and Z values here. You can use the below codes to generate a 3D surface in my example:
%generate a 3D surface
figure(1);subplot(1,2,1);
surf(X,Y,Z);colormap jet;
shading interp;
%see the (0,90) 2D surface;
view(0,90);subplot(1,2,2);
3D 2D
This is my method to extract the 2D surface:
view(0,90);
c=getframe(gca);
imwrite(c.cdata,'myimage.png');
I know this is good method to get the gca cdata. However, I have to generate millions of images. This method is a little slow. Could I know a direct method to generate a cdata matrix from some calculation with X Y and Z instead of using getframe()??
By the way, could I know how to write the cdata matrix to png files using the function writematrix()?
Thank you very much!!!!!!!!

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Image Analyst
Image Analyst 2022-3-13
编辑：Image Analyst 2022-3-13
You can just assign the matrix directly, like (untested)
load("X.mat");
load("Y.mat");
load("Z.mat");
tic
outputImage = zeros(1, 500, 'uint8');
xs = round(rescale(X, 1, 500));
ys = round(rescale(Y, 1, 500));
zs = round(rescale(Z, 0, 255));
for k = 1 : numel(xs)
outputImage(ys(k), xs(k)) = zs(k);
end
imshow(outputImage, 'ColorMap', jet(256), ...
'XData', [min(X, [], 'all'), max(X, [], 'all')], ...
'YData', [min(Y, [], 'all'), max(Y, [], 'all')] ...
);
axis('on', 'image')
toc
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Ke Zhang
Ke Zhang 2022-3-14
编辑：Ke Zhang 2022-3-14
I ran your code thanks. By the way, Could I know how to change the color in the four cornors to white? Thanks!
Image Analyst
Image Analyst 2022-3-14
If you're doing deep learning, those Z images are just sitting in a folder that you have an imageDataStore set up to point to.
To set the corners to white, set the values to 255
Z(1,1) = 255;
Z(1,end) = 255;
Z(end, 1) = 255;
Z(end, end) = 255;
Z=cat(3,Z,Z,Z);
% Then save to disk so your imageDatastore will point to it.

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