curvature versus slope
  n = 423875 
  X=0, Y = 12.12 +/- 10.60 
  Weighted least-squares fit:  Y = 17.5 + 4.190 X  + -0.04776 X**2 

slope versus dZ, curvature < 5
  n = 270073 
  X=0, Y = 10.31 +/- 5.59 
  Weighted least-squares fit:  Y = 10.4 + 0.535 X  + -0.00275 X**2 
     at X = 100, Y = 36.4 
     effective RMSE xy = 54.8 

slope versus dZ, curvature < 15
  n = 336822 
  X=0, Y = 10.91 +/- 5.98 
  Weighted least-squares fit:  Y = 9.8 + 0.798 X  + -0.00387 X**2 

curvature versus dZ, slope < 10
  n = 256688 
  X=0, Y = 11.31 +/- 6.93 
  Weighted least-squares fit:  Y = 10.7 + 3.118 X  + -0.08338 X**2 


Number of samples 426287
Max dz = 900
Mean dz = 21
RMS dz = 65.7267069006
100cm = 96.9780922243 percentile value of dz