curvature versus slope
  n = 270390 
  X=0, Y = 43.32 +/- 20.94 
  Weighted least-squares fit:  Y = 57.3 + 2.218 X  + -0.02396 X**2 

slope versus dZ, curvature < 5
  n = 96239 

  Weighted least-squares fit:  Y = 8.1 + 0.285 X  + 0.00190 X**2 
     at X = 100, Y = 55.6 
     effective RMSE xy = 86.4 

slope versus dZ, curvature < 15
  n = 174840 

  Weighted least-squares fit:  Y = 10.6 + 0.242 X  + 0.00263 X**2 

curvature versus dZ, slope < 10
  n = 2337 
  X=0, Y = 9.38 +/- 6.77 
  Weighted least-squares fit:  Y = 8.5 + 5.113 X  + -0.65624 X**2 


Number of samples 273175
Max dz = 900
Mean dz = 38
RMS dz = 69.0507060065
100cm = 92.5915621854 percentile value of dz