curvature versus slope
  n = 1984982 
  X=0, Y = 10.11 +/- 8.92 
  Weighted least-squares fit:  Y = 7.6 + 1.375 X  + -0.00626 X**2 

slope versus dZ, curvature < 5
  n = 131307 
  X=0, Y = 3.25 +/- 2.34 
  Weighted least-squares fit:  Y = 2.2 + 0.202 X  + -0.00102 X**2 
     at X = 100, Y = 12.2 
     effective RMSE xy = 18.9 

slope versus dZ, curvature < 15
  n = 481129 
  X=0, Y = 3.21 +/- 2.16 
  Weighted least-squares fit:  Y = 2.8 + 0.110 X  + 0.00091 X**2 

curvature versus dZ, slope < 10
  n = 1079762 
  X=0, Y = 3.11 +/- 2.24 
  Weighted least-squares fit:  Y = 3.0 + 0.148 X  + 0.00096 X**2 


Number of samples 1987224
Max dz = 900
Mean dz = 6
RMS dz = 17.0587221092
100cm = 99.8814929771 percentile value of dz
Mean dz (curv<=5) = 2
RMS dz (curv<=5) = 5.29150262213