curvature versus slope
  n = 75125 
  X=0, Y = 62.81 +/- 21.30 
  Weighted least-squares fit:  Y = 74.7 + 1.271 X  + -0.01355 X**2 

slope versus dZ, curvature < 5
  n = 11286 

  Weighted least-squares fit:  Y = 16.9 + 0.466 X  + 0.00083 X**2 
     at X = 100, Y = 71.8 
     effective RMSE xy = 109.6 

slope versus dZ, curvature < 15
  n = 25170 

  Weighted least-squares fit:  Y = 18.6 + 0.404 X  + 0.00214 X**2 

curvature versus dZ, slope < 10
  n = 111 
  X=0, Y = 20.82 +/- 8.95 
  Weighted least-squares fit:  Y = 24.5 + -3.521 X  + 0.22683 X**2 


Number of samples 75944
Max dz = 900
Mean dz = 83
RMS dz = 153.635933297
100cm = 76.0665753713 percentile value of dz