curvature versus slope
  n = 135428 
  X=0, Y = 65.14 +/- 23.21 
  Weighted least-squares fit:  Y = 73.0 + 1.030 X  + -0.01036 X**2 

slope versus dZ, curvature < 5
  n = 17348 

  Weighted least-squares fit:  Y = 7.2 + 3.296 X  + -0.02527 X**2 
     at X = 100, Y = 84.1 
     effective RMSE xy = 131.6 

slope versus dZ, curvature < 15
  n = 45980 

  Weighted least-squares fit:  Y = 25.5 + 2.424 X  + -0.01825 X**2 

curvature versus dZ, slope < 10
  n = 251 
  X=0, Y = 54.82 +/- 63.08 
  Weighted least-squares fit:  Y = 66.8 + -7.431 X  + 0.34150 X**2 


Number of samples 137817
Max dz = 900
Mean dz = 76
RMS dz = 125.279687101
100cm = 74.9609990059 percentile value of dz