curvature versus slope
  n = 303686 
  X=0, Y = 7.26 +/- 6.57 
  Weighted least-squares fit:  Y = 13.7 + 4.092 X  + -0.04492 X**2 

slope versus dZ, curvature < 5
  n = 162899 
  X=0, Y = 5.66 +/- 3.46 
  Weighted least-squares fit:  Y = 8.0 + 0.198 X  + 0.00110 X**2 
     at X = 100, Y = 38.8 
     effective RMSE xy = 59.6 

slope versus dZ, curvature < 15
  n = 219008 
  X=0, Y = 5.62 +/- 3.41 
  Weighted least-squares fit:  Y = 8.2 + 0.250 X  + 0.00145 X**2 

curvature versus dZ, slope < 10
  n = 191571 
  X=0, Y = 7.69 +/- 5.05 
  Weighted least-squares fit:  Y = 7.7 + 1.624 X  + 0.00446 X**2 


Number of samples 308352
Max dz = 900
Mean dz = 21
RMS dz = 49.223977897
100cm = 95.398440743 percentile value of dz