curvature versus slope
  n = 1381292 
  X=0, Y = 7.70 +/- 5.44 
  Weighted least-squares fit:  Y = 5.9 + 4.066 X  + -0.04790 X**2 

slope versus dZ, curvature < 5
  n = 751015 
  X=0, Y = 9.51 +/- 5.97 
  Weighted least-squares fit:  Y = 2.6 + 2.569 X  + -0.02412 X**2 
     at X = 100, Y = 18.3 
     effective RMSE xy = 28.5 

slope versus dZ, curvature < 15
  n = 1213771 
  X=0, Y = 9.54 +/- 5.83 
  Weighted least-squares fit:  Y = 6.4 + 2.109 X  + -0.01914 X**2 

curvature versus dZ, slope < 10
  n = 1005723 
  X=0, Y = 13.88 +/- 13.76 
  Weighted least-squares fit:  Y = 11.3 + 5.250 X  + -0.10495 X**2 


Number of samples 1438210
Max dz = 700
Mean dz = 22
RMS dz = 46.7867502612
100cm = 91.3253280119 percentile value of dz