curvature versus slope
  n = 651329 
  X=0, Y = 37.31 +/- 26.82 
  Weighted least-squares fit:  Y = 72.0 + 1.263 X  + -0.01349 X**2 

slope versus dZ, curvature < 5
  n = 24342 

  Weighted least-squares fit:  Y = 13.1 + 0.280 X  + 0.00286 X**2 
     at X = 100, Y = 69.7 
     effective RMSE xy = 107.6 

slope versus dZ, curvature < 15
  n = 68339 

  Weighted least-squares fit:  Y = 12.9 + 0.422 X  + 0.00218 X**2 

curvature versus dZ, slope < 10
  n = 4815 
  X=0, Y = 12.96 +/- 9.09 
  Weighted least-squares fit:  Y = 17.0 + 0.182 X  + 0.03954 X**2 


Number of samples 660664
Max dz = 900
Mean dz = 83
RMS dz = 117.37546592
100cm = 69.5177881646 percentile value of dz