curvature versus slope
  n = 29796 
  X=0, Y = 51.38 +/- 25.20 
  Weighted least-squares fit:  Y = 71.6 + 1.224 X  + -0.01252 X**2 

slope versus dZ, curvature < 5
  n = 2328 

  Weighted least-squares fit:  Y = 11.0 + -0.037 X  + 0.00458 X**2 
     at X = 100, Y = 53.1 
     effective RMSE xy = 81.6 

slope versus dZ, curvature < 15
  n = 4991 

  Weighted least-squares fit:  Y = 14.4 + -0.232 X  + 0.00837 X**2 

curvature versus dZ, slope < 10
  n = 216 
  X=0, Y = 7.57 +/- 5.59 
  Weighted least-squares fit:  Y = 7.8 + 2.333 X  + 0.08065 X**2 


Number of samples 30143
Max dz = 900
Mean dz = 100
RMS dz = 188.324188569
100cm = 66.921009853 percentile value of dz