curvature versus slope
  n = 97048 
  X=0, Y = 36.12 +/- 29.81 
  Weighted least-squares fit:  Y = 67.3 + 1.301 X  + -0.01337 X**2 

slope versus dZ, curvature < 5
  n = 4580 

  Weighted least-squares fit:  Y = 12.6 + 0.542 X  + -0.00010 X**2 
     at X = 100, Y = 65.9 
     effective RMSE xy = 101.6 

slope versus dZ, curvature < 15
  n = 11737 

  Weighted least-squares fit:  Y = 12.4 + 0.546 X  + 0.00055 X**2 

curvature versus dZ, slope < 10
  n = 2167 
  X=0, Y = 15.53 +/- 5.47 
  Weighted least-squares fit:  Y = 16.7 + -1.120 X  + 0.22992 X**2 


Number of samples 98050
Max dz = 900
Mean dz = 79
RMS dz = 159.471000499
100cm = 76.9015808261 percentile value of dz