curvature versus slope
  n = 601422 
  X=0, Y = 5.07 +/- 3.49 
  Weighted least-squares fit:  Y = 3.4 + 4.883 X  + -0.05577 X**2 

slope versus dZ, curvature < 5
  n = 459868 
  X=0, Y = 13.10 +/- 8.21 
  Weighted least-squares fit:  Y = 11.1 + 0.227 X  + -0.00127 X**2 
     at X = 100, Y = 21.1 
     effective RMSE xy = 28.2 

slope versus dZ, curvature < 15
  n = 569039 
  X=0, Y = 12.98 +/- 8.19 
  Weighted least-squares fit:  Y = 11.1 + 0.195 X  + 0.00132 X**2 

curvature versus dZ, slope < 10
  n = 548166 
  X=0, Y = 12.23 +/- 8.03 
  Weighted least-squares fit:  Y = 12.2 + -0.431 X  + 0.16907 X**2 


Number of samples 607291
Max dz = 900
Mean dz = 12
RMS dz = 25.179356624
100cm = 98.9571720971 percentile value of dz