curvature versus slope
  n = 538006 
  X=0, Y = 15.66 +/- 10.96 
  Weighted least-squares fit:  Y = 20.5 + 4.031 X  + -0.04521 X**2 

slope versus dZ, curvature < 5
  n = 268265 
  X=0, Y = 14.79 +/- 7.63 
  Weighted least-squares fit:  Y = 8.5 + 0.436 X  + 0.00015 X**2 
     at X = 100, Y = 53.6 
     effective RMSE xy = 83.1 

slope versus dZ, curvature < 15
  n = 397746 
  X=0, Y = 15.63 +/- 8.06 
  Weighted least-squares fit:  Y = 9.5 + 0.428 X  + 0.00016 X**2 

curvature versus dZ, slope < 10
  n = 194586 
  X=0, Y = 11.48 +/- 7.22 
  Weighted least-squares fit:  Y = 10.8 + 2.055 X  + 0.04892 X**2 


Number of samples 547879
Max dz = 900
Mean dz = 21
RMS dz = 39.7994974843
100cm = 97.5187952084 percentile value of dz