Consider going through the following MATLAB answers page:
If you want a 3-D line profile along certain defined line segments, load the image into MATLAB and use the "improfile" function to plot the intensity profile.
i1 = imread('<name of image>');
x = [19 427 416 77]; % Specify x- and y-coordinates that define connected line segments
y = [96 462 37 33];
improfile(i1,x,y),grid on; % Display a 3-D plot of the pixel values of these line segments.
