curvature versus slope
  n = 541878 
  X=0, Y = 8.85 +/- 8.06 
  Weighted least-squares fit:  Y = 18.0 + 3.697 X  + -0.04779 X**2 

slope versus dZ, curvature < 5
  n = 246565 
  X=0, Y = 9.89 +/- 5.06 
  Weighted least-squares fit:  Y = 8.1 + 0.208 X  + 0.00158 X**2 
     at X = 100, Y = 44.7 
     effective RMSE xy = 69.1 

slope versus dZ, curvature < 15
  n = 327513 
  X=0, Y = 9.98 +/- 5.28 
  Weighted least-squares fit:  Y = 7.8 + 0.324 X  + 0.00062 X**2 

curvature versus dZ, slope < 10
  n = 292859 
  X=0, Y = 9.12 +/- 4.97 
  Weighted least-squares fit:  Y = 7.5 + 2.010 X  + -0.02648 X**2 


Number of samples 553916
Max dz = 900
Mean dz = 23
RMS dz = 43.2781700168
100cm = 95.6592696366 percentile value of dz