curvature versus slope
  n = 625922 
  X=0, Y = 8.23 +/- 6.31 
  Weighted least-squares fit:  Y = 9.6 + 4.807 X  + -0.05542 X**2 

slope versus dZ, curvature < 5
  n = 402372 
  X=0, Y = 7.84 +/- 5.06 
  Weighted least-squares fit:  Y = 7.6 + 0.306 X  + -0.00019 X**2 
     at X = 100, Y = 36.3 
     effective RMSE xy = 55.8 

slope versus dZ, curvature < 15
  n = 535595 
  X=0, Y = 7.90 +/- 5.08 
  Weighted least-squares fit:  Y = 7.9 + 0.297 X  + 0.00020 X**2 

curvature versus dZ, slope < 10
  n = 455451 
  X=0, Y = 8.65 +/- 5.41 
  Weighted least-squares fit:  Y = 8.2 + 0.996 X  + 0.05976 X**2 


Number of samples 631127
Max dz = 800
Mean dz = 12
RMS dz = 22.4944437584
100cm = 99.078790798 percentile value of dz