title: How can I calculate curvature of each point on a surface?
body: <p>I have a point cloud and I first draw surface of these points using matlab(by centering of points).
  my points have 3D coordinates including (X,Y,Z). original of points are same:</p>
  
  <pre><code>    32512035.2100000    5401399.57000000    346.880000000000
  32512044.0300000    5401399.54000000    346.850000000000
  32512046.8900000    5401399.55000000    346.780000000000
  32512049.7800000    5401399.53000000    346.860000000000
  32512052.6900000    5401399.53000000    346.700000000000
  32512054.0300000    5401399.53000000    346.780000000000
  32512055.6900000    5401399.57000000    346.810000000000
  32512063.1200000    5401399.54000000    347.800000000000
  32512074.2300000    5401399.55000000    346.440000000000
  32512093.1200000    5401399.54000000    346.660000000000
  </code></pre>
  
  <p>and centering of them are: </p>
  
  <pre><code>-28.7291900003911   -3.97948997747153   -0.700859999999409
  -19.9091900000931   -4.00948997773230   -0.730859999999382
  -17.0491900006891   -3.99948997795582   -0.800859999999432
  -14.1591900000931   -4.01948997750878   -0.720859999999391
  -11.2491899999441   -4.01948997750878   -0.880859999999416
  -9.90919000009308   -4.01948997750878   -0.800859999999432
  -8.24918999994407   -3.97948997747153   -0.770859999999402
  -0.819190000242088  -4.00948997773230   0.219140000000607
  10.2908099991619    -3.99948997795582   -1.14085999999941
  29.1808099997579    -4.00948997773230   -0.920859999999379
  </code></pre>
  
  <p>and I draw surface using <code>fit</code> formula in matlab.</p>
  
  <p>I want to calculate curvature of each point and try <a href="http://www.mathworks.com/matlabcentral/fileexchange/11168-surface-curvature" rel="nofollow noreferrer">here</a> and <a href="http://www.mathworks.com/matlabcentral/fileexchange/10010-mean-curvature-fast-code/content/mcurvature_vec.m" rel="nofollow noreferrer">here</a> but I can't understand "The inputs (X,Y,Z) are 2D arrays corresponding to the surface being analyzed." thing.
  anybody to help me? or tell to me that how can I calculate curvature?</p>
  
  <p><img src="https://i.stack.imgur.com/82qeU.jpg" alt="enter image description here"></p>