curvature versus slope
  n = 787151 
  X=0, Y = 8.14 +/- 5.83 
  Weighted least-squares fit:  Y = 8.1 + 4.716 X  + -0.05698 X**2 

slope versus dZ, curvature < 5
  n = 539850 
  X=0, Y = 6.97 +/- 4.78 
  Weighted least-squares fit:  Y = 6.2 + 0.200 X  + 0.00208 X**2 
     at X = 100, Y = 47.1 
     effective RMSE xy = 73.3 

slope versus dZ, curvature < 15
  n = 693200 
  X=0, Y = 7.35 +/- 5.08 
  Weighted least-squares fit:  Y = 6.1 + 0.277 X  + 0.00138 X**2 

curvature versus dZ, slope < 10
  n = 554752 
  X=0, Y = 7.26 +/- 4.99 
  Weighted least-squares fit:  Y = 6.4 + 1.289 X  + 0.03951 X**2 


Number of samples 793105
Max dz = 700
Mean dz = 10
RMS dz = 21.4476105895
100cm = 99.1574886049 percentile value of dz