curvature versus slope
  n = 66995 
  X=0, Y = 51.50 +/- 28.88 
  Weighted least-squares fit:  Y = 74.3 + 1.046 X  + -0.01083 X**2 

slope versus dZ, curvature < 5
  n = 4009 

  Weighted least-squares fit:  Y = 36.7 + -0.678 X  + 0.00992 X**2 
     at X = 100, Y = 68.1 
     effective RMSE xy = 90.1 

slope versus dZ, curvature < 15
  n = 9393 

  Weighted least-squares fit:  Y = 34.9 + -0.525 X  + 0.01016 X**2 

curvature versus dZ, slope < 10
  n = 726 
  X=0, Y = 30.34 +/- 9.81 
  Weighted least-squares fit:  Y = 30.3 + 1.945 X  + -0.65692 X**2 


Number of samples 67801
Max dz = 900
Mean dz = 102
RMS dz = 151.515675757
100cm = 61.5521894957 percentile value of dz