curvature versus slope
  n = 434355 
  X=0, Y = 6.91 +/- 5.47 
  Weighted least-squares fit:  Y = 7.5 + 5.051 X  + -0.06496 X**2 

slope versus dZ, curvature < 5
  n = 331918 
  X=0, Y = 8.90 +/- 5.15 
  Weighted least-squares fit:  Y = 7.7 + 0.414 X  + 0.00022 X**2 
     at X = 100, Y = 51.4 
     effective RMSE xy = 79.8 

slope versus dZ, curvature < 15
  n = 403595 
  X=0, Y = 9.01 +/- 5.22 
  Weighted least-squares fit:  Y = 7.9 + 0.434 X  + 0.00012 X**2 

curvature versus dZ, slope < 10
  n = 355929 
  X=0, Y = 8.83 +/- 5.22 
  Weighted least-squares fit:  Y = 8.5 + 1.686 X  + 0.04311 X**2 


Number of samples 435984
Max dz = 500
Mean dz = 10
RMS dz = 18.2756668825
100cm = 99.5839296855 percentile value of dz