curvature versus slope
  n = 202661 
  X=0, Y = 24.06 +/- 22.90 
  Weighted least-squares fit:  Y = 74.8 + 1.155 X  + -0.01120 X**2 

slope versus dZ, curvature < 5
  n = 3558 

  Weighted least-squares fit:  Y = 4.1 + 0.370 X  + -0.00033 X**2 
     at X = 100, Y = 37.8 
     effective RMSE xy = 59.0 

slope versus dZ, curvature < 15
  n = 8121 

  Weighted least-squares fit:  Y = 2.5 + 0.699 X  + -0.00247 X**2 

curvature versus dZ, slope < 10
  n = 2793 
  X=0, Y = 6.35 +/- 3.79 
  Weighted least-squares fit:  Y = 6.1 + 1.403 X  + -0.13449 X**2 


Number of samples 207948
Max dz = 900
Mean dz = 66
RMS dz = 99.0706818388
100cm = 78.4277800219 percentile value of dz