curvature versus slope
  n = 4285313 
  X=0, Y = 5.90 +/- 3.57 
  Weighted least-squares fit:  Y = 3.7 + 4.902 X  + -0.04894 X**2 

slope versus dZ, curvature < 5
  n = 3018491 
  X=0, Y = 17.25 +/- 9.05 
  Weighted least-squares fit:  Y = 12.6 + 0.396 X  + -0.00017 X**2 
     at X = 100, Y = 50.5 
     effective RMSE xy = 76.8 

slope versus dZ, curvature < 15
  n = 4079079 
  X=0, Y = 17.63 +/- 9.42 
  Weighted least-squares fit:  Y = 12.7 + 0.424 X  + -0.00033 X**2 

curvature versus dZ, slope < 10
  n = 3785321 
  X=0, Y = 14.32 +/- 8.88 
  Weighted least-squares fit:  Y = 13.7 + 1.105 X  + -0.01716 X**2 


Number of samples 4303440
Max dz = 800
Mean dz = 13
RMS dz = 21.7715410571
100cm = 99.5513356756 percentile value of dz