curvature versus slope
  n = 325446 
  X=0, Y = 10.68 +/- 7.14 
  Weighted least-squares fit:  Y = 12.8 + 4.531 X  + -0.05160 X**2 

slope versus dZ, curvature < 5
  n = 196670 
  X=0, Y = 9.04 +/- 4.93 
  Weighted least-squares fit:  Y = 7.3 + 0.287 X  + 0.00013 X**2 
     at X = 100, Y = 37.3 
     effective RMSE xy = 57.4 

slope versus dZ, curvature < 15
  n = 267635 
  X=0, Y = 8.79 +/- 4.96 
  Weighted least-squares fit:  Y = 7.4 + 0.301 X  + 0.00053 X**2 

curvature versus dZ, slope < 10
  n = 189148 
  X=0, Y = 8.69 +/- 5.65 
  Weighted least-squares fit:  Y = 7.8 + 1.504 X  + -0.02726 X**2 


Number of samples 330165
Max dz = 800
Mean dz = 14
RMS dz = 29.3087017795
100cm = 98.4041312677 percentile value of dz