curvature versus slope
  n = 2739387 
  X=0, Y = 12.06 +/- 9.45 
  Weighted least-squares fit:  Y = 17.3 + 4.622 X  + -0.05275 X**2 

slope versus dZ, curvature < 5
  n = 987072 
  X=0, Y = 13.98 +/- 7.42 
  Weighted least-squares fit:  Y = 30.3 + 0.561 X  + -0.00297 X**2 
     at X = 100, Y = 56.7 
     effective RMSE xy = 75.2 

slope versus dZ, curvature < 15
  n = 1761677 
  X=0, Y = 13.98 +/- 7.42 
  Weighted least-squares fit:  Y = 32.4 + 0.487 X  + -0.00174 X**2 

curvature versus dZ, slope < 10
  n = 1121569 
  X=0, Y = 30.09 +/- 23.82 
  Weighted least-squares fit:  Y = 31.8 + 2.936 X  + -0.08378 X**2 


Number of samples 2786534
Max dz = 900
Mean dz = 39
RMS dz = 58.617403559
100cm = 93.0985231115 percentile value of dz