curvature versus slope
  n = 1941388 
  X=0, Y = 14.64 +/- 10.82 
  Weighted least-squares fit:  Y = 20.1 + 3.893 X  + -0.04300 X**2 

slope versus dZ, curvature < 5
  n = 646407 
  X=0, Y = 5.70 +/- 3.72 
  Weighted least-squares fit:  Y = 13.5 + 0.047 X  + 0.00164 X**2 
     at X = 100, Y = 34.6 
     effective RMSE xy = 50.1 

slope versus dZ, curvature < 15
  n = 1100400 
  X=0, Y = 7.25 +/- 5.09 
  Weighted least-squares fit:  Y = 13.4 + 0.154 X  + 0.00149 X**2 

curvature versus dZ, slope < 10
  n = 549864 
  X=0, Y = 12.47 +/- 9.53 
  Weighted least-squares fit:  Y = 11.7 + 2.594 X  + -0.06255 X**2 


Number of samples 1980570
Max dz = 900
Mean dz = 25
RMS dz = 46.0977222865
100cm = 95.6116673483 percentile value of dz