curvature versus slope
  n = 116036 
  X=0, Y = 12.92 +/- 10.10 
  Weighted least-squares fit:  Y = 10.1 + 1.408 X  + -0.00709 X**2 

slope versus dZ, curvature < 5
  n = 3309 

  Weighted least-squares fit:  Y = 2.3 + 0.117 X  + -0.00031 X**2 
     at X = 100, Y = 11.0 
     effective RMSE xy = 16.9 

slope versus dZ, curvature < 15
  n = 14638 
  X=0, Y = 1.31 +/- 0.71 
  Weighted least-squares fit:  Y = 1.7 + 0.218 X  + -0.00146 X**2 

curvature versus dZ, slope < 10
  n = 44455 
  X=0, Y = 2.74 +/- 1.96 
  Weighted least-squares fit:  Y = 2.7 + 0.162 X  + 0.00115 X**2 


Number of samples 116159
Max dz = 900
Mean dz = 7
RMS dz = 16.4924225025
100cm = 99.8863626581 percentile value of dz
Mean dz (curv<=5) = 2
RMS dz (curv<=5) = 7.93725393319