curvature versus slope
  n = 921793 
  X=0, Y = 12.68 +/- 8.37 
  Weighted least-squares fit:  Y = 20.8 + 4.330 X  + -0.04989 X**2 

slope versus dZ, curvature < 5
  n = 403871 
  X=0, Y = 4.65 +/- 3.48 
  Weighted least-squares fit:  Y = 9.6 + 1.119 X  + -0.00437 X**2 
     at X = 100, Y = 77.8 
     effective RMSE xy = 121.3 

slope versus dZ, curvature < 15
  n = 617095 
  X=0, Y = 5.64 +/- 4.41 
  Weighted least-squares fit:  Y = 11.0 + 1.115 X  + -0.00392 X**2 

curvature versus dZ, slope < 10
  n = 297841 
  X=0, Y = 13.87 +/- 11.54 
  Weighted least-squares fit:  Y = 14.6 + 3.415 X  + -0.08269 X**2 


Number of samples 931586
Max dz = 900
Mean dz = 38
RMS dz = 76.889531147
100cm = 91.5994873259 percentile value of dz