curvature versus slope
  n = 1564320 
  X=0, Y = 31.14 +/- 24.37 
  Weighted least-squares fit:  Y = 63.0 + 1.703 X  + -0.01705 X**2 

slope versus dZ, curvature < 5
  n = 44847 

  Weighted least-squares fit:  Y = 12.3 + 0.098 X  + 0.00039 X**2 
     at X = 100, Y = 26.0 
     effective RMSE xy = 36.0 

slope versus dZ, curvature < 15
  n = 113206 

  Weighted least-squares fit:  Y = 11.1 + 0.209 X  + 0.00015 X**2 

curvature versus dZ, slope < 10
  n = 9770 
  X=0, Y = 12.87 +/- 8.29 
  Weighted least-squares fit:  Y = 13.5 + -0.052 X  + 0.05154 X**2 


Number of samples 1580908
Max dz = 600
Mean dz = 52
RMS dz = 75.3989389846
100cm = 84.8316916607 percentile value of dz