curvature versus slope
  n = 2444978 
  X=0, Y = 14.56 +/- 11.90 
  Weighted least-squares fit:  Y = 14.2 + 1.255 X  + -0.00644 X**2 

slope versus dZ, curvature < 5
  n = 30946 
  X=0, Y = 5.39 +/- 2.88 
  Weighted least-squares fit:  Y = 3.3 + 0.150 X  + 0.00033 X**2 
     at X = 100, Y = 21.6 
     effective RMSE xy = 33.6 

slope versus dZ, curvature < 15
  n = 126745 
  X=0, Y = 4.16 +/- 2.39 
  Weighted least-squares fit:  Y = 3.5 + 0.128 X  + 0.00096 X**2 

curvature versus dZ, slope < 10
  n = 523955 
  X=0, Y = 4.62 +/- 3.16 
  Weighted least-squares fit:  Y = 4.1 + 0.135 X  + 0.00162 X**2 


Number of samples 2448940
Max dz = 900
Mean dz = 11
RMS dz = 22.0227155455
100cm = 99.805630191 percentile value of dz
Mean dz (curv<=5) = 4
RMS dz (curv<=5) = 17.691806013