curvature versus slope
  n = 443904 
  X=0, Y = 9.93 +/- 8.18 
  Weighted least-squares fit:  Y = 19.7 + 4.278 X  + -0.05010 X**2 

slope versus dZ, curvature < 5
  n = 228289 
  X=0, Y = 12.16 +/- 7.90 
  Weighted least-squares fit:  Y = 15.0 + -0.174 X  + 0.00575 X**2 
     at X = 100, Y = 55.1 
     effective RMSE xy = 83.3 

slope versus dZ, curvature < 15
  n = 301474 
  X=0, Y = 12.06 +/- 7.43 
  Weighted least-squares fit:  Y = 14.2 + 0.039 X  + 0.00379 X**2 

curvature versus dZ, slope < 10
  n = 237543 
  X=0, Y = 14.61 +/- 7.79 
  Weighted least-squares fit:  Y = 13.7 + 1.118 X  + 0.12010 X**2 


Number of samples 453371
Max dz = 900
Mean dz = 26
RMS dz = 48.795491595
100cm = 95.0197520353 percentile value of dz