curvature versus slope
  n = 455293 
  X=0, Y = 6.28 +/- 3.60 
  Weighted least-squares fit:  Y = 6.0 + 0.149 X  + 0.00954 X**2 

slope versus dZ, curvature < 5
  n = 83324 
  X=0, Y = 3.83 +/- 2.51 
  Weighted least-squares fit:  Y = 5.4 + 0.156 X  + -0.00007 X**2 
     at X = 100, Y = 20.3 
     effective RMSE xy = 30.8 

slope versus dZ, curvature < 15
  n = 214140 
  X=0, Y = 6.04 +/- 4.16 
  Weighted least-squares fit:  Y = 5.5 + 0.160 X  + -0.00024 X**2 

curvature versus dZ, slope < 10
  n = 408206 
  X=0, Y = 5.93 +/- 3.69 
  Weighted least-squares fit:  Y = 5.4 + 0.267 X  + -0.00071 X**2 


Number of samples 455303
Max dz = 150
Mean dz = 5
RMS dz = 7.0
100cm = 99.9978036604 percentile value of dz
Mean dz (curv<=5) = 4
RMS dz (curv<=5) = 6.0827625303