curvature versus slope
  n = 1077692 
  X=0, Y = 6.10 +/- 3.90 
  Weighted least-squares fit:  Y = 3.5 + 5.895 X  + -0.08533 X**2 

slope versus dZ, curvature < 5
  n = 813584 
  X=0, Y = 16.18 +/- 9.59 
  Weighted least-squares fit:  Y = 16.5 + 0.383 X  + -0.00124 X**2 
     at X = 100, Y = 42.4 
     effective RMSE xy = 61.3 

slope versus dZ, curvature < 15
  n = 1032914 
  X=0, Y = 16.48 +/- 9.66 
  Weighted least-squares fit:  Y = 17.0 + 0.374 X  + -0.00061 X**2 

curvature versus dZ, slope < 10
  n = 970921 
  X=0, Y = 17.71 +/- 10.25 
  Weighted least-squares fit:  Y = 17.7 + 0.673 X  + 0.17852 X**2 


Number of samples 1079315
Max dz = 900
Mean dz = 16
RMS dz = 21.0713075057
100cm = 99.8300774102 percentile value of dz