curvature versus slope
  n = 1056134 
  X=0, Y = 33.77 +/- 25.24 
  Weighted least-squares fit:  Y = 43.8 + 2.077 X  + -0.02055 X**2 

slope versus dZ, curvature < 5
  n = 69844 
  X=0, Y = 30.11 +/- 10.41 
  Weighted least-squares fit:  Y = 23.1 + 0.837 X  + -0.00441 X**2 
     at X = 100, Y = 62.7 
     effective RMSE xy = 91.5 

slope versus dZ, curvature < 15
  n = 211002 
  X=0, Y = 30.36 +/- 9.70 
  Weighted least-squares fit:  Y = 25.4 + 0.879 X  + -0.00427 X**2 

curvature versus dZ, slope < 10
  n = 29751 
  X=0, Y = 24.66 +/- 13.06 
  Weighted least-squares fit:  Y = 25.5 + 3.093 X  + -0.02324 X**2 


Number of samples 1077368
Max dz = 900
Mean dz = 66
RMS dz = 118.266647877
100cm = 81.5267392386 percentile value of dz