curvature versus slope
  n = 521885 
  X=0, Y = 16.02 +/- 10.84 
  Weighted least-squares fit:  Y = 20.0 + 4.422 X  + -0.05065 X**2 

slope versus dZ, curvature < 5
  n = 330824 
  X=0, Y = 4.53 +/- 3.27 
  Weighted least-squares fit:  Y = 4.8 + 0.128 X  + 0.00227 X**2 
     at X = 100, Y = 40.3 
     effective RMSE xy = 62.8 

slope versus dZ, curvature < 15
  n = 432589 
  X=0, Y = 5.41 +/- 3.91 
  Weighted least-squares fit:  Y = 4.5 + 0.259 X  + 0.00249 X**2 

curvature versus dZ, slope < 10
  n = 191283 
  X=0, Y = 5.05 +/- 3.41 
  Weighted least-squares fit:  Y = 4.7 + 1.506 X  + 0.12448 X**2 


Number of samples 533531
Max dz = 900
Mean dz = 16
RMS dz = 42.320207939
100cm = 96.4206391006 percentile value of dz