curvature versus slope
  n = 57559 
  X=0, Y = 63.54 +/- 29.31 
  Weighted least-squares fit:  Y = 67.4 + 1.349 X  + -0.01314 X**2 

slope versus dZ, curvature < 5
  n = 1576 

  Weighted least-squares fit:  Y = 7.9 + 0.912 X  + -0.00099 X**2 
     at X = 100, Y = 89.2 
     effective RMSE xy = 139.5 

slope versus dZ, curvature < 15
  n = 6594 

  Weighted least-squares fit:  Y = 15.4 + 0.676 X  + 0.00166 X**2 

curvature versus dZ, slope < 10
  n = 84 
  X=0, Y = 20.70 +/- 10.79 
  Weighted least-squares fit:  Y = 19.0 + -0.834 X  + 0.35234 X**2 


Number of samples 58034
Max dz = 900
Mean dz = 111
RMS dz = 200.81085628
100cm = 63.3749181514 percentile value of dz