curvature versus slope
  n = 451775 
  X=0, Y = 6.40 +/- 5.10 
  Weighted least-squares fit:  Y = 7.1 + 5.313 X  + -0.08364 X**2 

slope versus dZ, curvature < 5
  n = 286376 
  X=0, Y = 9.48 +/- 5.36 
  Weighted least-squares fit:  Y = 7.9 + 0.362 X  + -0.00088 X**2 
     at X = 100, Y = 35.3 
     effective RMSE xy = 54.0 

slope versus dZ, curvature < 15
  n = 368229 
  X=0, Y = 9.51 +/- 5.42 
  Weighted least-squares fit:  Y = 8.1 + 0.408 X  + -0.00051 X**2 

curvature versus dZ, slope < 10
  n = 346797 
  X=0, Y = 9.24 +/- 5.33 
  Weighted least-squares fit:  Y = 9.0 + 1.096 X  + -0.01975 X**2 


Number of samples 460634
Max dz = 500
Mean dz = 15
RMS dz = 27.8747197295
100cm = 97.7691616337 percentile value of dz