curvature versus slope
  n = 375065 
  X=0, Y = 17.77 +/- 12.09 
  Weighted least-squares fit:  Y = 26.5 + 3.681 X  + -0.04126 X**2 

slope versus dZ, curvature < 5
  n = 115144 
  X=0, Y = 14.11 +/- 6.81 
  Weighted least-squares fit:  Y = 12.1 + 0.589 X  + 0.00110 X**2 
     at X = 100, Y = 82.1 
     effective RMSE xy = 127.6 

slope versus dZ, curvature < 15
  n = 214823 
  X=0, Y = 12.99 +/- 7.18 
  Weighted least-squares fit:  Y = 12.1 + 0.626 X  + 0.00085 X**2 

curvature versus dZ, slope < 10
  n = 72977 
  X=0, Y = 16.61 +/- 8.20 
  Weighted least-squares fit:  Y = 16.3 + 0.462 X  + 0.13790 X**2 


Number of samples 378269
Max dz = 900
Mean dz = 37
RMS dz = 67.1490878568
100cm = 92.7548913604 percentile value of dz