curvature versus slope
  n = 903258 
  X=0, Y = 6.72 +/- 4.97 
  Weighted least-squares fit:  Y = 6.2 + 4.689 X  + -0.04957 X**2 

slope versus dZ, curvature < 5
  n = 569121 
  X=0, Y = 8.93 +/- 6.96 
  Weighted least-squares fit:  Y = 9.1 + 0.370 X  + 0.00010 X**2 
     at X = 100, Y = 47.1 
     effective RMSE xy = 72.6 

slope versus dZ, curvature < 15
  n = 796788 
  X=0, Y = 9.30 +/- 7.22 
  Weighted least-squares fit:  Y = 9.5 + 0.405 X  + -0.00002 X**2 

curvature versus dZ, slope < 10
  n = 691090 
  X=0, Y = 10.27 +/- 6.89 
  Weighted least-squares fit:  Y = 9.9 + 1.633 X  + 0.08265 X**2 


Number of samples 910226
Max dz = 900
Mean dz = 12
RMS dz = 25.3179778023
100cm = 99.1738315539 percentile value of dz