curvature versus slope
  n = 165764 
  X=0, Y = 38.55 +/- 13.54 
  Weighted least-squares fit:  Y = 44.9 + 2.704 X  + -0.03003 X**2 

slope versus dZ, curvature < 5
  n = 77715 

  Weighted least-squares fit:  Y = 7.8 + 0.907 X  + -0.00224 X**2 
     at X = 100, Y = 76.1 
     effective RMSE xy = 118.9 

slope versus dZ, curvature < 15
  n = 110777 

  Weighted least-squares fit:  Y = 8.3 + 0.919 X  + -0.00187 X**2 

curvature versus dZ, slope < 10
  n = 788 
  X=0, Y = 17.21 +/- 10.21 
  Weighted least-squares fit:  Y = 17.4 + -1.594 X  + 0.71818 X**2 


Number of samples 169329
Max dz = 900
Mean dz = 50
RMS dz = 92.876261768
100cm = 90.6099959251 percentile value of dz