curvature versus slope
  n = 264815 
  X=0, Y = 50.35 +/- 25.50 
  Weighted least-squares fit:  Y = 64.2 + 1.500 X  + -0.01604 X**2 

slope versus dZ, curvature < 5
  n = 36101 

  Weighted least-squares fit:  Y = 9.9 + 0.242 X  + 0.00283 X**2 
     at X = 100, Y = 62.4 
     effective RMSE xy = 96.8 

slope versus dZ, curvature < 15
  n = 79373 

  Weighted least-squares fit:  Y = 9.6 + 0.376 X  + 0.00194 X**2 

curvature versus dZ, slope < 10
  n = 3047 
  X=0, Y = 13.79 +/- 10.29 
  Weighted least-squares fit:  Y = 10.6 + 2.360 X  + 0.01023 X**2 


Number of samples 272396
Max dz = 900
Mean dz = 62
RMS dz = 97.1236325515
100cm = 80.805885549 percentile value of dz