curvature versus slope
  n = 159243 
  X=0, Y = 22.89 +/- 21.89 
  Weighted least-squares fit:  Y = 51.5 + 2.356 X  + -0.02658 X**2 

slope versus dZ, curvature < 5
  n = 37891 
  X=0, Y = 3.97 +/- 3.75 
  Weighted least-squares fit:  Y = 4.9 + 0.827 X  + 0.00115 X**2 
     at X = 100, Y = 99.0 
     effective RMSE xy = 155.4 

slope versus dZ, curvature < 15
  n = 58243 
  X=0, Y = 3.97 +/- 3.75 
  Weighted least-squares fit:  Y = 4.5 + 1.003 X  + -0.00010 X**2 

curvature versus dZ, slope < 10
  n = 23048 
  X=0, Y = 8.49 +/- 7.23 
  Weighted least-squares fit:  Y = 8.3 + 4.253 X  + -0.00349 X**2 


Number of samples 161071
Max dz = 900
Mean dz = 78
RMS dz = 198.607653428
100cm = 78.5864618709 percentile value of dz
Mean dz (curv<=5) = 18
RMS dz (curv<=5) = 71.1688133946