curvature versus slope
  n = 1234084 
  X=0, Y = 20.41 +/- 14.41 
  Weighted least-squares fit:  Y = 75.1 + 1.173 X  + -0.01154 X**2 

slope versus dZ, curvature < 5
  n = 5623 

  Weighted least-squares fit:  Y = 8.3 + 0.381 X  + -0.00073 X**2 
     at X = 100, Y = 39.1 
     effective RMSE xy = 60.1 

slope versus dZ, curvature < 15
  n = 30748 

  Weighted least-squares fit:  Y = 8.4 + 0.554 X  + -0.00116 X**2 

curvature versus dZ, slope < 10
  n = 2228 
  X=0, Y = 7.92 +/- 4.62 
  Weighted least-squares fit:  Y = 7.9 + 3.845 X  + -0.21714 X**2 


Number of samples 1246099
Max dz = 900
Mean dz = 60
RMS dz = 82.9216497665
100cm = 81.5991345792 percentile value of dz