curvature versus slope
  n = 137962 
  X=0, Y = 63.84 +/- 21.25 
  Weighted least-squares fit:  Y = 70.2 + 1.236 X  + -0.01303 X**2 

slope versus dZ, curvature < 5
  n = 41752 

  Weighted least-squares fit:  Y = 3.5 + 0.934 X  + -0.00291 X**2 
     at X = 100, Y = 67.8 
     effective RMSE xy = 106.4 

slope versus dZ, curvature < 15
  n = 82252 

  Weighted least-squares fit:  Y = 6.6 + 0.840 X  + -0.00188 X**2 

curvature versus dZ, slope < 10
  n = 260 
  X=0, Y = 14.55 +/- 6.99 
  Weighted least-squares fit:  Y = 12.4 + 3.013 X  + -0.18211 X**2 


Number of samples 139246
Max dz = 900
Mean dz = 72
RMS dz = 144.260181616
100cm = 86.755095299 percentile value of dz