curvature versus slope
  n = 1145855 
  X=0, Y = 52.24 +/- 27.44 
  Weighted least-squares fit:  Y = 66.4 + 1.405 X  + -0.01491 X**2 

slope versus dZ, curvature < 5
  n = 97615 

  Weighted least-squares fit:  Y = 11.5 + 0.372 X  + 0.00067 X**2 
     at X = 100, Y = 55.4 
     effective RMSE xy = 85.1 

slope versus dZ, curvature < 15
  n = 290596 

  Weighted least-squares fit:  Y = 13.5 + 0.416 X  + 0.00040 X**2 

curvature versus dZ, slope < 10
  n = 6512 
  X=0, Y = 11.05 +/- 7.98 
  Weighted least-squares fit:  Y = 13.4 + 1.557 X  + 0.06595 X**2 


Number of samples 1165892
Max dz = 900
Mean dz = 56
RMS dz = 83.1624915452
100cm = 83.4577302186 percentile value of dz