curvature versus slope
  n = 2665961 
  X=0, Y = 4.59 +/- 2.80 
  Weighted least-squares fit:  Y = 2.7 + 5.697 X  + -0.08067 X**2 

slope versus dZ, curvature < 5
  n = 2020709 
  X=0, Y = 5.64 +/- 5.85 
  Weighted least-squares fit:  Y = 10.9 + 0.337 X  + 0.00054 X**2 
     at X = 100, Y = 50.0 
     effective RMSE xy = 76.7 

slope versus dZ, curvature < 15
  n = 2544302 
  X=0, Y = 5.81 +/- 5.97 
  Weighted least-squares fit:  Y = 11.0 + 0.361 X  + 0.00057 X**2 

curvature versus dZ, slope < 10
  n = 2395683 
  X=0, Y = 11.74 +/- 8.66 
  Weighted least-squares fit:  Y = 11.6 + 1.393 X  + -0.03903 X**2 


Number of samples 2668065
Max dz = 500
Mean dz = 10
RMS dz = 15.2970585408
100cm = 99.9034131477 percentile value of dz