curvature versus slope
  n = 155460 
  X=0, Y = 38.50 +/- 14.98 
  Weighted least-squares fit:  Y = 47.5 + 2.460 X  + -0.02618 X**2 

slope versus dZ, curvature < 5
  n = 58560 

  Weighted least-squares fit:  Y = 19.4 + 0.248 X  + 0.00377 X**2 
     at X = 100, Y = 81.8 
     effective RMSE xy = 124.8 

slope versus dZ, curvature < 15
  n = 93515 

  Weighted least-squares fit:  Y = 18.4 + 0.346 X  + 0.00335 X**2 

curvature versus dZ, slope < 10
  n = 1936 
  X=0, Y = 25.81 +/- 8.18 
  Weighted least-squares fit:  Y = 25.8 + 0.023 X  + 0.09381 X**2 


Number of samples 156742
Max dz = 900
Mean dz = 51
RMS dz = 107.046718773
100cm = 89.596917227 percentile value of dz