curvature versus slope
  n = 240614 
  X=0, Y = 40.73 +/- 18.66 
  Weighted least-squares fit:  Y = 50.8 + 2.338 X  + -0.02595 X**2 

slope versus dZ, curvature < 5
  n = 97925 

  Weighted least-squares fit:  Y = 39.2 + 0.384 X  + 0.00146 X**2 
     at X = 100, Y = 92.2 
     effective RMSE xy = 131.1 

slope versus dZ, curvature < 15
  n = 144933 
  X=0, Y = 25.00 +/- 10.00 
  Weighted least-squares fit:  Y = 39.3 + 0.368 X  + 0.00144 X**2 

curvature versus dZ, slope < 10
  n = 4996 
  X=0, Y = 42.46 +/- 15.35 
  Weighted least-squares fit:  Y = 43.7 + -1.491 X  + 0.18757 X**2 


Number of samples 247505
Max dz = 900
Mean dz = 67
RMS dz = 95.4306030579
100cm = 83.8799216177 percentile value of dz