curvature versus slope
  n = 159380 
  X=0, Y = 71.08 +/- 16.20 
  Weighted least-squares fit:  Y = 71.4 + 1.190 X  + -0.01155 X**2 

slope versus dZ, curvature < 5
  n = 16755 

  Weighted least-squares fit:  Y = 15.5 + 0.518 X  + -0.00013 X**2 
     at X = 100, Y = 65.9 
     effective RMSE xy = 100.6 

slope versus dZ, curvature < 15
  n = 54072 

  Weighted least-squares fit:  Y = 19.5 + 0.415 X  + 0.00079 X**2 

curvature versus dZ, slope < 10
  n = 63 

  Weighted least-squares fit:  Y = 6.3 + 5.463 X  + -0.20273 X**2 


Number of samples 161118
Max dz = 900
Mean dz = 66
RMS dz = 101.852835012
100cm = 84.093645651 percentile value of dz