curvature versus slope
  n = 852632 
  X=0, Y = 4.91 +/- 2.91 
  Weighted least-squares fit:  Y = 3.6 + 4.887 X  + -0.05368 X**2 

slope versus dZ, curvature < 5
  n = 642260 
  X=0, Y = 8.98 +/- 5.03 
  Weighted least-squares fit:  Y = 7.2 + 0.515 X  + -0.00190 X**2 
     at X = 100, Y = 39.7 
     effective RMSE xy = 61.3 

slope versus dZ, curvature < 15
  n = 806785 
  X=0, Y = 9.07 +/- 5.17 
  Weighted least-squares fit:  Y = 7.6 + 0.546 X  + -0.00178 X**2 

curvature versus dZ, slope < 10
  n = 780448 
  X=0, Y = 8.74 +/- 4.99 
  Weighted least-squares fit:  Y = 8.2 + 1.519 X  + 0.10206 X**2 


Number of samples 854969
Max dz = 900
Mean dz = 9
RMS dz = 18.3575597507
100cm = 99.6988194894 percentile value of dz