curvature versus slope
  n = 194667 
  X=0, Y = 49.58 +/- 24.99 
  Weighted least-squares fit:  Y = 61.3 + 1.905 X  + -0.02024 X**2 

slope versus dZ, curvature < 5
  n = 93189 

  Weighted least-squares fit:  Y = 22.9 + 0.264 X  + -0.00063 X**2 
     at X = 100, Y = 43.0 
     effective RMSE xy = 57.2 

slope versus dZ, curvature < 15
  n = 151788 

  Weighted least-squares fit:  Y = 23.2 + 0.262 X  + -0.00026 X**2 

curvature versus dZ, slope < 10
  n = 5871 
  X=0, Y = 21.82 +/- 7.23 
  Weighted least-squares fit:  Y = 21.6 + 1.991 X  + -0.33317 X**2 


Number of samples 195529
Max dz = 900
Mean dz = 35
RMS dz = 76.4329771761
100cm = 97.1385318802 percentile value of dz