curvature versus slope
  n = 657316 
  X=0, Y = 9.11 +/- 7.59 
  Weighted least-squares fit:  Y = 19.2 + 4.094 X  + -0.04644 X**2 

slope versus dZ, curvature < 5
  n = 300061 
  X=0, Y = 12.56 +/- 8.30 
  Weighted least-squares fit:  Y = 9.1 + 0.614 X  + -0.00108 X**2 
     at X = 100, Y = 59.7 
     effective RMSE xy = 92.6 

slope versus dZ, curvature < 15
  n = 407913 
  X=0, Y = 12.55 +/- 8.35 
  Weighted least-squares fit:  Y = 9.2 + 0.664 X  + -0.00146 X**2 

curvature versus dZ, slope < 10
  n = 308434 
  X=0, Y = 11.78 +/- 7.65 
  Weighted least-squares fit:  Y = 10.9 + 1.687 X  + 0.07181 X**2 


Number of samples 664311
Max dz = 900
Mean dz = 28
RMS dz = 64.4437739429
100cm = 94.6488918594 percentile value of dz