curvature versus slope
  n = 451406 
  X=0, Y = 8.32 +/- 5.75 
  Weighted least-squares fit:  Y = 9.4 + 4.354 X  + -0.04657 X**2 

slope versus dZ, curvature < 5
  n = 250575 
  X=0, Y = 11.88 +/- 5.72 
  Weighted least-squares fit:  Y = 10.0 + 0.180 X  + 0.00061 X**2 
     at X = 100, Y = 34.1 
     effective RMSE xy = 51.2 

slope versus dZ, curvature < 15
  n = 365108 
  X=0, Y = 11.58 +/- 5.83 
  Weighted least-squares fit:  Y = 10.0 + 0.197 X  + 0.00116 X**2 

curvature versus dZ, slope < 10
  n = 292723 
  X=0, Y = 10.74 +/- 6.45 
  Weighted least-squares fit:  Y = 9.4 + 1.565 X  + 0.01098 X**2 


Number of samples 453568
Max dz = 900
Mean dz = 12
RMS dz = 25.7099202644
100cm = 99.4774763652 percentile value of dz