curvature versus slope
  n = 6477905 
  X=0, Y = 23.12 +/- 22.20 
  Weighted least-squares fit:  Y = 14.0 + 4.936 X  + -0.05547 X**2 

slope versus dZ, curvature < 5
  n = 2271950 
  X=0, Y = 49.74 +/- 17.57 
  Weighted least-squares fit:  Y = 18.2 + 0.309 X  + -0.00061 X**2 
     at X = 100, Y = 42.9 
     effective RMSE xy = 61.0 

slope versus dZ, curvature < 15
  n = 4144645 
  X=0, Y = 49.74 +/- 17.57 
  Weighted least-squares fit:  Y = 18.7 + 0.202 X  + 0.00012 X**2 

curvature versus dZ, slope < 10
  n = 2778669 
  X=0, Y = 31.69 +/- 21.71 
  Weighted least-squares fit:  Y = 22.5 + -1.742 X  + 0.21354 X**2 


Number of samples 6593070
Max dz = 900
Mean dz = 24
RMS dz = 38.170669368
100cm = 97.3578621189 percentile value of dz