curvature versus slope
  n = 728918 
  X=0, Y = 8.77 +/- 6.08 
  Weighted least-squares fit:  Y = 13.2 + 4.701 X  + -0.05424 X**2 

slope versus dZ, curvature < 5
  n = 484527 
  X=0, Y = 11.45 +/- 7.43 
  Weighted least-squares fit:  Y = 6.8 + 0.452 X  + -0.00003 X**2 
     at X = 100, Y = 51.7 
     effective RMSE xy = 80.5 

slope versus dZ, curvature < 15
  n = 589186 
  X=0, Y = 11.73 +/- 7.55 
  Weighted least-squares fit:  Y = 7.0 + 0.475 X  + -0.00005 X**2 

curvature versus dZ, slope < 10
  n = 473380 
  X=0, Y = 8.48 +/- 6.24 
  Weighted least-squares fit:  Y = 7.5 + 2.439 X  + -0.03080 X**2 


Number of samples 744419
Max dz = 900
Mean dz = 17
RMS dz = 38.7169213652
100cm = 97.2163526186 percentile value of dz