curvature versus slope
  n = 1302561 
  X=0, Y = 12.84 +/- 9.75 
  Weighted least-squares fit:  Y = 16.4 + 4.501 X  + -0.05123 X**2 

slope versus dZ, curvature < 5
  n = 603093 
  X=0, Y = 8.13 +/- 4.37 
  Weighted least-squares fit:  Y = 17.1 + 0.425 X  + -0.00217 X**2 
     at X = 100, Y = 37.9 
     effective RMSE xy = 53.1 

slope versus dZ, curvature < 15
  n = 975253 
  X=0, Y = 7.98 +/- 4.49 
  Weighted least-squares fit:  Y = 18.9 + 0.428 X  + -0.00076 X**2 

curvature versus dZ, slope < 10
  n = 625847 
  X=0, Y = 16.72 +/- 13.20 
  Weighted least-squares fit:  Y = 18.5 + 2.660 X  + -0.02167 X**2 


Number of samples 1328097
Max dz = 900
Mean dz = 26
RMS dz = 47.9270278653
100cm = 95.5769796935 percentile value of dz