curvature versus slope
  n = 290338 
  X=0, Y = 65.69 +/- 37.64 
  Weighted least-squares fit:  Y = 77.9 + 0.734 X  + -0.00660 X**2 

slope versus dZ, curvature < 5
  n = 2124 

  Weighted least-squares fit:  Y = 5.2 + 0.449 X  + -0.00067 X**2 
     at X = 100, Y = 43.4 
     effective RMSE xy = 67.7 

slope versus dZ, curvature < 15
  n = 10752 

  Weighted least-squares fit:  Y = 6.6 + 0.489 X  + -0.00079 X**2 

curvature versus dZ, slope < 10
  n = 593 
  X=0, Y = 7.46 +/- 4.10 
  Weighted least-squares fit:  Y = 5.5 + 2.987 X  + -0.05886 X**2 


Number of samples 295634
Max dz = 900
Mean dz = 60
RMS dz = 90.9670269933
100cm = 82.1640947929 percentile value of dz