curvature versus slope
  n = 1588630 
  X=0, Y = 13.06 +/- 11.57 
  Weighted least-squares fit:  Y = 9.9 + 1.623 X  + -0.00981 X**2 

slope versus dZ, curvature < 5
  n = 88293 
  X=0, Y = 3.34 +/- 2.17 
  Weighted least-squares fit:  Y = 2.5 + 0.168 X  + -0.00058 X**2 
     at X = 100, Y = 13.6 
     effective RMSE xy = 20.9 

slope versus dZ, curvature < 15
  n = 321624 
  X=0, Y = 3.30 +/- 2.10 
  Weighted least-squares fit:  Y = 2.9 + 0.106 X  + 0.00095 X**2 

curvature versus dZ, slope < 10
  n = 647064 
  X=0, Y = 3.40 +/- 2.18 
  Weighted least-squares fit:  Y = 3.2 + 0.117 X  + 0.00169 X**2 


Number of samples 1590892
Max dz = 900
Mean dz = 7
RMS dz = 18.8679622641
100cm = 99.8448669049 percentile value of dz
Mean dz (curv<=5) = 3
RMS dz (curv<=5) = 6.16441400297