curvature versus slope
  n = 1907533 
  X=0, Y = 5.48 +/- 4.35 
  Weighted least-squares fit:  Y = 5.0 + 4.835 X  + -0.05342 X**2 

slope versus dZ, curvature < 5
  n = 1423859 
  X=0, Y = 5.90 +/- 3.88 
  Weighted least-squares fit:  Y = 7.9 + 0.144 X  + 0.00054 X**2 
     at X = 100, Y = 27.7 
     effective RMSE xy = 41.7 

slope versus dZ, curvature < 15
  n = 1785969 
  X=0, Y = 6.30 +/- 4.25 
  Weighted least-squares fit:  Y = 8.3 + 0.141 X  + 0.00125 X**2 

curvature versus dZ, slope < 10
  n = 1670457 
  X=0, Y = 7.25 +/- 4.89 
  Weighted least-squares fit:  Y = 7.5 + 1.341 X  + 0.04170 X**2 


Number of samples 1913081
Max dz = 800
Mean dz = 8
RMS dz = 16.9705627485
100cm = 99.6779017721 percentile value of dz