curvature versus slope
  n = 178662 
  X=0, Y = 12.24 +/- 9.73 
  Weighted least-squares fit:  Y = 19.6 + 4.048 X  + -0.04434 X**2 

slope versus dZ, curvature < 5
  n = 77531 
  X=0, Y = 7.81 +/- 5.19 
  Weighted least-squares fit:  Y = 6.4 + 0.438 X  + -0.00054 X**2 
     at X = 100, Y = 44.8 
     effective RMSE xy = 69.6 

slope versus dZ, curvature < 15
  n = 119096 
  X=0, Y = 8.08 +/- 5.31 
  Weighted least-squares fit:  Y = 6.6 + 0.426 X  + 0.00080 X**2 

curvature versus dZ, slope < 10
  n = 74606 
  X=0, Y = 9.19 +/- 5.85 
  Weighted least-squares fit:  Y = 8.3 + 1.025 X  + 0.06242 X**2 


Number of samples 180645
Max dz = 900
Mean dz = 21
RMS dz = 53.7494186015
100cm = 96.3253895762 percentile value of dz