curvature versus slope
  n = 112131 
  X=0, Y = 67.40 +/- 34.42 
  Weighted least-squares fit:  Y = 78.0 + 0.709 X  + -0.00681 X**2 

slope versus dZ, curvature < 5
  n = 1845 

  Weighted least-squares fit:  Y = 0.3 + 1.123 X  + -0.00275 X**2 
     at X = 100, Y = 85.1 
     effective RMSE xy = 133.7 

slope versus dZ, curvature < 15
  n = 7641 

  Weighted least-squares fit:  Y = 7.1 + 1.046 X  + -0.00264 X**2 

curvature versus dZ, slope < 10
  n = 103 
  X=0, Y = 4.97 +/- 1.73 
  Weighted least-squares fit:  Y = 5.5 + 3.087 X  + 0.02142 X**2 


Number of samples 112836
Max dz = 900
Mean dz = 89
RMS dz = 157.143246753
100cm = 68.6447587649 percentile value of dz