curvature versus slope
  n = 649249 
  X=0, Y = 34.28 +/- 18.22 
  Weighted least-squares fit:  Y = 42.8 + 2.676 X  + -0.02880 X**2 

slope versus dZ, curvature < 5
  n = 95532 

  Weighted least-squares fit:  Y = 10.9 + 0.452 X  + 0.00107 X**2 
     at X = 100, Y = 66.7 
     effective RMSE xy = 103.4 

slope versus dZ, curvature < 15
  n = 284166 

  Weighted least-squares fit:  Y = 11.9 + 0.425 X  + 0.00164 X**2 

curvature versus dZ, slope < 10
  n = 11739 
  X=0, Y = 13.71 +/- 8.34 
  Weighted least-squares fit:  Y = 14.5 + 0.719 X  + 0.06013 X**2 


Number of samples 660469
Max dz = 900
Mean dz = 47
RMS dz = 74.9466476902
100cm = 88.6733518151 percentile value of dz