curvature versus slope
  n = 1069484 
  X=0, Y = 44.59 +/- 28.96 
  Weighted least-squares fit:  Y = 68.0 + 1.344 X  + -0.01393 X**2 

slope versus dZ, curvature < 5
  n = 24422 

  Weighted least-squares fit:  Y = 62.6 + -0.159 X  + 0.00506 X**2 
     at X = 100, Y = 97.4 
     effective RMSE xy = 117.1 

slope versus dZ, curvature < 15
  n = 100740 

  Weighted least-squares fit:  Y = 62.6 + -0.131 X  + 0.00463 X**2 

curvature versus dZ, slope < 10
  n = 3717 
  X=0, Y = 64.67 +/- 29.18 
  Weighted least-squares fit:  Y = 70.1 + -1.416 X  + 0.14487 X**2 


Number of samples 1076371
Max dz = 900
Mean dz = 85
RMS dz = 110.747460467
100cm = 66.4309982339 percentile value of dz