curvature versus slope
  n = 401765 
  X=0, Y = 7.53 +/- 6.25 
  Weighted least-squares fit:  Y = 8.1 + 5.195 X  + -0.06205 X**2 

slope versus dZ, curvature < 5
  n = 262016 
  X=0, Y = 20.26 +/- 13.50 
  Weighted least-squares fit:  Y = 26.8 + -0.293 X  + 0.00358 X**2 
     at X = 100, Y = 33.4 
     effective RMSE xy = 31.2 

slope versus dZ, curvature < 15
  n = 363624 
  X=0, Y = 20.60 +/- 13.40 
  Weighted least-squares fit:  Y = 27.2 + -0.308 X  + 0.00422 X**2 

curvature versus dZ, slope < 10
  n = 327574 
  X=0, Y = 26.72 +/- 18.84 
  Weighted least-squares fit:  Y = 25.9 + 0.914 X  + -0.02252 X**2 


Number of samples 405039
Max dz = 600
Mean dz = 21
RMS dz = 31.6859590355
100cm = 99.043302003 percentile value of dz