curvature versus slope
  n = 304330 
  X=0, Y = 10.33 +/- 7.41 
  Weighted least-squares fit:  Y = 12.2 + 4.476 X  + -0.04936 X**2 

slope versus dZ, curvature < 5
  n = 183797 
  X=0, Y = 8.96 +/- 5.93 
  Weighted least-squares fit:  Y = 10.2 + 0.037 X  + 0.00165 X**2 
     at X = 100, Y = 30.4 
     effective RMSE xy = 44.9 

slope versus dZ, curvature < 15
  n = 252800 
  X=0, Y = 9.47 +/- 6.27 
  Weighted least-squares fit:  Y = 10.5 + 0.028 X  + 0.00280 X**2 

curvature versus dZ, slope < 10
  n = 192741 
  X=0, Y = 10.56 +/- 6.72 
  Weighted least-squares fit:  Y = 9.7 + 1.372 X  + 0.00003 X**2 


Number of samples 309401
Max dz = 900
Mean dz = 14
RMS dz = 34.7994252826
100cm = 98.2120290497 percentile value of dz