curvature versus slope
  n = 397721 
  X=0, Y = 6.73 +/- 4.96 
  Weighted least-squares fit:  Y = 4.9 + 5.132 X  + -0.06024 X**2 

slope versus dZ, curvature < 5
  n = 280369 
  X=0, Y = 7.26 +/- 4.98 
  Weighted least-squares fit:  Y = 7.1 + 0.563 X  + -0.00434 X**2 
     at X = 100, Y = 20.0 
     effective RMSE xy = 29.4 

slope versus dZ, curvature < 15
  n = 373171 
  X=0, Y = 7.87 +/- 5.42 
  Weighted least-squares fit:  Y = 8.0 + 0.436 X  + -0.00146 X**2 

curvature versus dZ, slope < 10
  n = 341576 
  X=0, Y = 9.43 +/- 6.55 
  Weighted least-squares fit:  Y = 9.2 + 0.833 X  + 0.12832 X**2 


Number of samples 399003
Max dz = 900
Mean dz = 10
RMS dz = 18.4932420089
100cm = 99.6521329414 percentile value of dz