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Most of matlab's 3D routines require the values to be on a regular
2D grid.
Suppose you have some 3D coordinates contained in 3 vectors x, y and z but the (x,y) points don't lie on a regular grid. You can use
plot3 to display the individual points, but to display
surfaces you need to do more work
% first define a regular grid. Suppose the x and y values lie between
% 0 and 100, and that we want 20 gridlines each way
steps = linspace(0,100,20);
[XI,YI] = meshgrid(steps, steps);
% now extrapolate  find z values for these grid points
ZI = griddata(x,y,z,XI, YI);
% display this mesh with the original data
mesh(XI,YI,ZI);
hold
plot3(x,y,z);
hold off
Matlab has 3D interpolation facilities too.