curvature versus slope
  n = 3725565 
  X=0, Y = 32.84 +/- 27.17 
  Weighted least-squares fit:  Y = 47.2 + 1.292 X  + -0.01057 X**2 

slope versus dZ, curvature < 5
  n = 107393 

  Weighted least-squares fit:  Y = 2.8 + 0.207 X  + 0.00007 X**2 
     at X = 100, Y = 24.2 
     effective RMSE xy = 37.8 

slope versus dZ, curvature < 15
  n = 493187 
  X=0, Y = 5.14 +/- 2.79 
  Weighted least-squares fit:  Y = 3.0 + 0.220 X  + 0.00009 X**2 

curvature versus dZ, slope < 10
  n = 521291 
  X=0, Y = 4.10 +/- 3.05 
  Weighted least-squares fit:  Y = 3.9 + 0.273 X  + -0.00314 X**2 


Number of samples 3792143
Max dz = 900
Mean dz = 574
RMS dz = 4391.5394795
100cm = 99.8745827887 percentile value of dz
Mean dz (curv<=5) = 164
RMS dz (curv<=5) = 2416.99565577