curvature versus slope
  n = 210837 
  X=0, Y = 36.07 +/- 28.42 
  Weighted least-squares fit:  Y = 76.0 + 0.868 X  + -0.00898 X**2 

slope versus dZ, curvature < 5
  n = 5969 

  Weighted least-squares fit:  Y = 42.2 + 0.609 X  + -0.00002 X**2 
     at X = 100, Y = 102.8 
     effective RMSE xy = 147.3 

slope versus dZ, curvature < 15
  n = 15404 

  Weighted least-squares fit:  Y = 41.9 + 0.741 X  + -0.00081 X**2 

curvature versus dZ, slope < 10
  n = 1584 
  X=0, Y = 47.10 +/- 12.56 
  Weighted least-squares fit:  Y = 46.3 + 2.350 X  + -0.08362 X**2 


Number of samples 211624
Max dz = 900
Mean dz = 105
RMS dz = 136.956197377
100cm = 57.273277133 percentile value of dz