curvature versus slope
  n = 150825 
  X=0, Y = 42.47 +/- 19.31 
  Weighted least-squares fit:  Y = 53.9 + 2.351 X  + -0.02499 X**2 

slope versus dZ, curvature < 5
  n = 24931 

  Weighted least-squares fit:  Y = 18.8 + 0.952 X  + -0.00336 X**2 
     at X = 100, Y = 80.4 
     effective RMSE xy = 122.8 

slope versus dZ, curvature < 15
  n = 50508 

  Weighted least-squares fit:  Y = 27.0 + 0.652 X  + -0.00116 X**2 

curvature versus dZ, slope < 10
  n = 282 
  X=0, Y = 45.46 +/- 30.02 
  Weighted least-squares fit:  Y = 48.9 + -5.936 X  + 0.82446 X**2 


Number of samples 154665
Max dz = 900
Mean dz = 68
RMS dz = 99.4886928249
100cm = 78.7308052889 percentile value of dz