curvature versus slope
  n = 2148278 
  X=0, Y = 7.83 +/- 5.31 
  Weighted least-squares fit:  Y = 8.1 + 4.755 X  + -0.04811 X**2 

slope versus dZ, curvature < 5
  n = 1302250 
  X=0, Y = 10.17 +/- 5.75 
  Weighted least-squares fit:  Y = 13.4 + 0.278 X  + 0.00115 X**2 
     at X = 100, Y = 52.7 
     effective RMSE xy = 80.1 

slope versus dZ, curvature < 15
  n = 1902672 
  X=0, Y = 10.20 +/- 5.66 
  Weighted least-squares fit:  Y = 13.2 + 0.406 X  + 0.00008 X**2 

curvature versus dZ, slope < 10
  n = 1651992 
  X=0, Y = 14.00 +/- 9.68 
  Weighted least-squares fit:  Y = 14.8 + 1.109 X  + 0.03208 X**2 


Number of samples 2182782
Max dz = 900
Mean dz = 17
RMS dz = 33.0907842155
100cm = 98.2790768845 percentile value of dz