curvature versus slope
  n = 828238 
  X=0, Y = 17.46 +/- 15.04 
  Weighted least-squares fit:  Y = 44.6 + 2.803 X  + -0.03078 X**2 

slope versus dZ, curvature < 5
  n = 146494 
  X=0, Y = 76.32 +/- 7.85 
  Weighted least-squares fit:  Y = 70.8 + -0.487 X  + 0.00422 X**2 
     at X = 100, Y = 64.3 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 301496 
  X=0, Y = 71.29 +/- 17.51 
  Weighted least-squares fit:  Y = 70.5 + -0.431 X  + 0.00334 X**2 

curvature versus dZ, slope < 10
  n = 120626 
  X=0, Y = 67.66 +/- 24.75 
  Weighted least-squares fit:  Y = 67.4 + -0.741 X  + 0.07903 X**2 


Number of samples 841151
Max dz = 900
Mean dz = 66
RMS dz = 89.4818417334
100cm = 82.2710785578 percentile value of dz