curvature versus slope
  n = 453481 
  X=0, Y = 8.88 +/- 7.14 
  Weighted least-squares fit:  Y = 8.2 + 5.187 X  + -0.06319 X**2 

slope versus dZ, curvature < 5
  n = 302749 
  X=0, Y = 8.69 +/- 4.81 
  Weighted least-squares fit:  Y = 7.3 + 0.147 X  + 0.00208 X**2 
     at X = 100, Y = 42.8 
     effective RMSE xy = 66.2 

slope versus dZ, curvature < 15
  n = 412792 
  X=0, Y = 8.72 +/- 4.91 
  Weighted least-squares fit:  Y = 7.2 + 0.228 X  + 0.00120 X**2 

curvature versus dZ, slope < 10
  n = 353835 
  X=0, Y = 7.56 +/- 4.57 
  Weighted least-squares fit:  Y = 7.4 + 0.679 X  + 0.14099 X**2 


Number of samples 455841
Max dz = 900
Mean dz = 9
RMS dz = 24.1246761636
100cm = 99.4357681736 percentile value of dz