curvature versus slope
  n = 199700 
  X=0, Y = 11.88 +/- 11.32 
  Weighted least-squares fit:  Y = 25.0 + 4.109 X  + -0.04797 X**2 

slope versus dZ, curvature < 5
  n = 140463 
  X=0, Y = 4.24 +/- 4.89 
  Weighted least-squares fit:  Y = 11.9 + 0.630 X  + 0.00206 X**2 
     at X = 100, Y = 95.5 
     effective RMSE xy = 148.9 

slope versus dZ, curvature < 15
  n = 156669 
  X=0, Y = 4.26 +/- 4.89 
  Weighted least-squares fit:  Y = 11.7 + 0.724 X  + 0.00231 X**2 

curvature versus dZ, slope < 10
  n = 123548 
  X=0, Y = 14.32 +/- 12.14 
  Weighted least-squares fit:  Y = 15.2 + 2.160 X  + 0.06274 X**2 


Number of samples 202121
Max dz = 900
Mean dz = 43
RMS dz = 134.88513632
100cm = 90.8238134583 percentile value of dz
Mean dz (curv<=5) = 13
RMS dz (curv<=5) = 37.563279942