curvature versus slope
  n = 281937 
  X=0, Y = 48.67 +/- 35.15 
  Weighted least-squares fit:  Y = 51.9 + 0.873 X  + -0.00539 X**2 

slope versus dZ, curvature < 5
  n = 3061 

  Weighted least-squares fit:  Y = 9.9 + -0.084 X  + 0.00260 X**2 
     at X = 100, Y = 27.5 
     effective RMSE xy = 40.3 

slope versus dZ, curvature < 15
  n = 11940 

  Weighted least-squares fit:  Y = 9.2 + -0.023 X  + 0.00193 X**2 

curvature versus dZ, slope < 10
  n = 16944 
  X=0, Y = 8.83 +/- 5.36 
  Weighted least-squares fit:  Y = 9.1 + -0.011 X  + 0.00110 X**2 


Number of samples 282309
Max dz = 400
Mean dz = 16
RMS dz = 21.610182785
100cm = 99.8522895126 percentile value of dz
Mean dz (curv<=5) = 11
RMS dz (curv<=5) = 14.3527000944