curvature versus slope
  n = 577752 
  X=0, Y = 12.29 +/- 8.84 
  Weighted least-squares fit:  Y = 13.5 + 4.209 X  + -0.04407 X**2 

slope versus dZ, curvature < 5
  n = 270848 
  X=0, Y = 6.18 +/- 4.35 
  Weighted least-squares fit:  Y = 12.4 + 0.433 X  + -0.00229 X**2 
     at X = 100, Y = 32.8 
     effective RMSE xy = 47.7 

slope versus dZ, curvature < 15
  n = 433600 
  X=0, Y = 6.14 +/- 4.29 
  Weighted least-squares fit:  Y = 15.1 + 0.341 X  + -0.00121 X**2 

curvature versus dZ, slope < 10
  n = 246784 
  X=0, Y = 13.62 +/- 10.92 
  Weighted least-squares fit:  Y = 13.7 + 3.704 X  + -0.10856 X**2 


Number of samples 585822
Max dz = 700
Mean dz = 20
RMS dz = 33.4215499341
100cm = 98.5031289368 percentile value of dz