curvature versus slope
  n = 191451 
  X=0, Y = 62.31 +/- 23.85 
  Weighted least-squares fit:  Y = 69.7 + 1.290 X  + -0.01227 X**2 

slope versus dZ, curvature < 5
  n = 2445 

  Weighted least-squares fit:  Y = 9.5 + 0.346 X  + -0.00147 X**2 
     at X = 100, Y = 29.3 
     effective RMSE xy = 43.5 

slope versus dZ, curvature < 15
  n = 13248 

  Weighted least-squares fit:  Y = 12.1 + 0.236 X  + -0.00015 X**2 

curvature versus dZ, slope < 10
  n = 86 

  Weighted least-squares fit:  Y = 12.8 + 1.246 X  + -0.00414 X**2 


Number of samples 192964
Max dz = 900
Mean dz = 46
RMS dz = 70.9788700953
100cm = 88.9352418068 percentile value of dz