curvature versus slope
  n = 464454 
  X=0, Y = 33.11 +/- 26.29 
  Weighted least-squares fit:  Y = 67.0 + 1.384 X  + -0.01427 X**2 

slope versus dZ, curvature < 5
  n = 13023 

  Weighted least-squares fit:  Y = 71.4 + 0.062 X  + 0.00147 X**2 
     at X = 100, Y = 92.3 
     effective RMSE xy = 92.0 

slope versus dZ, curvature < 15
  n = 37282 

  Weighted least-squares fit:  Y = 69.4 + 0.126 X  + 0.00149 X**2 

curvature versus dZ, slope < 10
  n = 4299 
  X=0, Y = 72.94 +/- 24.37 
  Weighted least-squares fit:  Y = 69.7 + 1.336 X  + -0.06122 X**2 


Number of samples 469365
Max dz = 900
Mean dz = 93
RMS dz = 122.686592585
100cm = 63.02280741 percentile value of dz