curvature versus slope
  n = 410123 
  X=0, Y = 50.24 +/- 20.79 
  Weighted least-squares fit:  Y = 58.4 + 2.150 X  + -0.02418 X**2 

slope versus dZ, curvature < 5
  n = 186544 

  Weighted least-squares fit:  Y = 9.5 + 0.751 X  + -0.00240 X**2 
     at X = 100, Y = 60.6 
     effective RMSE xy = 94.1 

slope versus dZ, curvature < 15
  n = 310757 

  Weighted least-squares fit:  Y = 9.9 + 0.764 X  + -0.00202 X**2 

curvature versus dZ, slope < 10
  n = 5587 
  X=0, Y = 16.50 +/- 9.67 
  Weighted least-squares fit:  Y = 16.2 + 1.434 X  + 0.01749 X**2 


Number of samples 413052
Max dz = 900
Mean dz = 42
RMS dz = 62.0805927807
100cm = 95.0468706119 percentile value of dz