curvature versus slope
  n = 164629 
  X=0, Y = 46.67 +/- 30.79 
  Weighted least-squares fit:  Y = 64.9 + 1.393 X  + -0.01409 X**2 

slope versus dZ, curvature < 5
  n = 6839 

  Weighted least-squares fit:  Y = 9.2 + 0.187 X  + 0.00287 X**2 
     at X = 100, Y = 56.6 
     effective RMSE xy = 87.7 

slope versus dZ, curvature < 15
  n = 23989 

  Weighted least-squares fit:  Y = 9.5 + 0.249 X  + 0.00258 X**2 

curvature versus dZ, slope < 10
  n = 1550 
  X=0, Y = 11.67 +/- 8.16 
  Weighted least-squares fit:  Y = 9.7 + 1.408 X  + 0.00708 X**2 


Number of samples 166211
Max dz = 900
Mean dz = 58
RMS dz = 103.812330674
100cm = 83.6689509118 percentile value of dz