curvature versus slope
  n = 487569 
  X=0, Y = 13.11 +/- 11.31 
  Weighted least-squares fit:  Y = 24.7 + 2.528 X  + -0.02629 X**2 

slope versus dZ, curvature < 5
  n = 160656 
  X=0, Y = 6.99 +/- 4.35 
  Weighted least-squares fit:  Y = 5.9 + 0.461 X  + -0.00034 X**2 
     at X = 100, Y = 48.7 
     effective RMSE xy = 75.9 

slope versus dZ, curvature < 15
  n = 245831 
  X=0, Y = 6.87 +/- 4.34 
  Weighted least-squares fit:  Y = 6.4 + 0.451 X  + 0.00001 X**2 

curvature versus dZ, slope < 10
  n = 171978 
  X=0, Y = 8.30 +/- 5.62 
  Weighted least-squares fit:  Y = 6.0 + 2.884 X  + -0.00988 X**2 


Number of samples 500167
Max dz = 800
Mean dz = 23
RMS dz = 39.1535439009
100cm = 95.7484200277 percentile value of dz