curvature versus slope
  n = 205869 
  X=0, Y = 72.22 +/- 21.77 
  Weighted least-squares fit:  Y = 75.4 + 1.116 X  + -0.01072 X**2 

slope versus dZ, curvature < 5
  n = 5337 

  Weighted least-squares fit:  Y = 6.2 + 0.692 X  + -0.00310 X**2 
     at X = 100, Y = 44.3 
     effective RMSE xy = 68.9 

slope versus dZ, curvature < 15
  n = 31094 

  Weighted least-squares fit:  Y = 10.8 + 0.582 X  + -0.00162 X**2 

curvature versus dZ, slope < 10
  n = 72 

  Weighted least-squares fit:  Y = 23.7 + -3.897 X  + 0.43681 X**2 


Number of samples 209469
Max dz = 900
Mean dz = 59
RMS dz = 96.8762096699
100cm = 83.7088065537 percentile value of dz