curvature versus slope
  n = 485219783 
  X=0, Y = 19.77 +/- 18.66 
  Weighted least-squares fit:  Y = 39.5 + 3.108 X  + -0.03433 X**2 

slope versus dZ, curvature < 5
  n = 121598644 
  X=0, Y = 8.44 +/- 7.94 
  Weighted least-squares fit:  Y = 12.1 + 0.873 X  + -0.00369 X**2 
     at X = 100, Y = 62.5 
     effective RMSE xy = 96.3 

slope versus dZ, curvature < 15
  n = 206228101 
  X=0, Y = 8.75 +/- 8.11 
  Weighted least-squares fit:  Y = 13.2 + 0.795 X  + -0.00281 X**2 

curvature versus dZ, slope < 10
  n = 113354709 
  X=0, Y = 15.04 +/- 12.67 
  Weighted least-squares fit:  Y = 14.1 + 2.666 X  + -0.00401 X**2 


Number of samples 490021434
Max dz = 900
Mean dz = 41
RMS dz = 72.6360791893
100cm = 89.5335896674 percentile value of dz
Mean dz (curv<=5) = 15
RMS dz (curv<=5) = 28.2842712475