curvature versus slope
  n = 789089 
  X=0, Y = 7.77 +/- 6.61 
  Weighted least-squares fit:  Y = 7.6 + 4.466 X  + -0.04718 X**2 

slope versus dZ, curvature < 5
  n = 417675 
  X=0, Y = 8.69 +/- 6.16 
  Weighted least-squares fit:  Y = 8.8 + 0.374 X  + -0.00040 X**2 
     at X = 100, Y = 42.2 
     effective RMSE xy = 64.8 

slope versus dZ, curvature < 15
  n = 643386 
  X=0, Y = 8.99 +/- 6.29 
  Weighted least-squares fit:  Y = 9.6 + 0.432 X  + -0.00060 X**2 

curvature versus dZ, slope < 10
  n = 558367 
  X=0, Y = 9.60 +/- 6.01 
  Weighted least-squares fit:  Y = 9.1 + 2.507 X  + -0.04604 X**2 


Number of samples 792160
Max dz = 900
Mean dz = 12
RMS dz = 21.0
100cm = 99.5647343971 percentile value of dz