curvature versus slope
  n = 2377567 
  X=0, Y = 8.33 +/- 6.14 
  Weighted least-squares fit:  Y = 8.7 + 5.271 X  + -0.06152 X**2 

slope versus dZ, curvature < 5
  n = 1497789 
  X=0, Y = 18.74 +/- 9.91 
  Weighted least-squares fit:  Y = 18.7 + 0.324 X  + 0.00103 X**2 
     at X = 100, Y = 61.4 
     effective RMSE xy = 91.9 

slope versus dZ, curvature < 15
  n = 2083495 
  X=0, Y = 19.32 +/- 10.49 
  Weighted least-squares fit:  Y = 18.1 + 0.437 X  + 0.00029 X**2 

curvature versus dZ, slope < 10
  n = 1770892 
  X=0, Y = 20.27 +/- 12.12 
  Weighted least-squares fit:  Y = 20.3 + 0.622 X  + 0.00177 X**2 


Number of samples 2400538
Max dz = 900
Mean dz = 22
RMS dz = 45.8257569496
100cm = 98.3032970109 percentile value of dz