curvature versus slope
  n = 207589 
  X=0, Y = 3.23 +/- 1.97 
  Weighted least-squares fit:  Y = 3.2 + 1.586 X  + -0.09051 X**2 

slope versus dZ, curvature < 5
  n = 201612 
  X=0, Y = 4.34 +/- 5.46 
  Weighted least-squares fit:  Y = 6.4 + 1.471 X  + -0.07483 X**2 
     at X = 100, Y = -594.8 
     effective RMSE xy = 934.3 

slope versus dZ, curvature < 15
  n = 207391 
  X=0, Y = 4.38 +/- 5.50 
  Weighted least-squares fit:  Y = 6.5 + 1.436 X  + -0.06746 X**2 

curvature versus dZ, slope < 10
  n = 206391 
  X=0, Y = 9.68 +/- 8.84 
  Weighted least-squares fit:  Y = 9.7 + 2.998 X  + -0.24685 X**2 


Number of samples 207589
Max dz = 83
Mean dz = 6
RMS dz = 10.5356537529
100cm = 0 percentile value of dz