curvature versus slope
  n = 2245016 
  X=0, Y = 36.66 +/- 21.70 
  Weighted least-squares fit:  Y = 32.8 + 1.264 X  + -0.00811 X**2 

slope versus dZ, curvature < 5
  n = 15985 

  Weighted least-squares fit:  Y = 3.1 + 0.101 X  + 0.00111 X**2 
     at X = 100, Y = 24.2 
     effective RMSE xy = 37.7 

slope versus dZ, curvature < 15
  n = 80994 

  Weighted least-squares fit:  Y = 3.6 + 0.061 X  + 0.00170 X**2 

curvature versus dZ, slope < 10
  n = 86632 
  X=0, Y = 4.32 +/- 2.45 
  Weighted least-squares fit:  Y = 4.0 + 0.134 X  + 0.00107 X**2 


Number of samples 2250725
Max dz = 900
Mean dz = 13
RMS dz = 21.400934559
100cm = 99.6950316009 percentile value of dz
Mean dz (curv<=5) = 6
RMS dz (curv<=5) = 8.77496438739