curvature versus slope
  n = 837495 
  X=0, Y = 13.87 +/- 9.30 
  Weighted least-squares fit:  Y = 17.7 + 4.236 X  + -0.04694 X**2 

slope versus dZ, curvature < 5
  n = 395589 
  X=0, Y = 7.16 +/- 4.56 
  Weighted least-squares fit:  Y = 6.4 + 0.415 X  + -0.00013 X**2 
     at X = 100, Y = 46.6 
     effective RMSE xy = 72.5 

slope versus dZ, curvature < 15
  n = 607598 
  X=0, Y = 10.27 +/- 6.74 
  Weighted least-squares fit:  Y = 6.9 + 0.427 X  + 0.00017 X**2 

curvature versus dZ, slope < 10
  n = 328606 
  X=0, Y = 8.87 +/- 5.30 
  Weighted least-squares fit:  Y = 8.2 + 1.457 X  + 0.05793 X**2 


Number of samples 852285
Max dz = 900
Mean dz = 20
RMS dz = 46.2060602086
100cm = 96.8339229248 percentile value of dz