curvature versus slope
  n = 383697 
  X=0, Y = 54.19 +/- 32.03 
  Weighted least-squares fit:  Y = 73.3 + 0.866 X  + -0.00792 X**2 

slope versus dZ, curvature < 5
  n = 7143 

  Weighted least-squares fit:  Y = 17.5 + 0.287 X  + -0.00028 X**2 
     at X = 100, Y = 43.5 
     effective RMSE xy = 62.5 

slope versus dZ, curvature < 15
  n = 30242 

  Weighted least-squares fit:  Y = 18.3 + 0.367 X  + -0.00088 X**2 

curvature versus dZ, slope < 10
  n = 815 
  X=0, Y = 17.84 +/- 8.06 
  Weighted least-squares fit:  Y = 21.0 + -0.466 X  + 0.12723 X**2 


Number of samples 387325
Max dz = 900
Mean dz = 51
RMS dz = 83.1083629968
100cm = 87.4715032595 percentile value of dz