curvature versus slope
  n = 471344 
  X=0, Y = 8.50 +/- 5.49 
  Weighted least-squares fit:  Y = 11.7 + 4.585 X  + -0.05200 X**2 

slope versus dZ, curvature < 5
  n = 283891 
  X=0, Y = 8.96 +/- 6.06 
  Weighted least-squares fit:  Y = 7.9 + 0.379 X  + 0.00079 X**2 
     at X = 100, Y = 53.7 
     effective RMSE xy = 83.4 

slope versus dZ, curvature < 15
  n = 381883 
  X=0, Y = 9.31 +/- 6.31 
  Weighted least-squares fit:  Y = 7.9 + 0.445 X  + 0.00055 X**2 

curvature versus dZ, slope < 10
  n = 322805 
  X=0, Y = 10.35 +/- 6.34 
  Weighted least-squares fit:  Y = 9.7 + 0.979 X  + 0.05143 X**2 


Number of samples 478556
Max dz = 900
Mean dz = 19
RMS dz = 50.2692749102
100cm = 96.4808716221 percentile value of dz