curvature versus slope
  n = 218064 
  X=0, Y = 58.16 +/- 35.12 
  Weighted least-squares fit:  Y = 80.1 + 0.650 X  + -0.00640 X**2 

slope versus dZ, curvature < 5
  n = 3982 

  Weighted least-squares fit:  Y = 12.9 + 0.338 X  + 0.00226 X**2 
     at X = 100, Y = 69.3 
     effective RMSE xy = 107.0 

slope versus dZ, curvature < 15
  n = 14083 

  Weighted least-squares fit:  Y = 11.6 + 0.491 X  + 0.00129 X**2 

curvature versus dZ, slope < 10
  n = 461 
  X=0, Y = 21.15 +/- 13.94 
  Weighted least-squares fit:  Y = 16.8 + 1.404 X  + 0.08430 X**2 


Number of samples 220170
Max dz = 900
Mean dz = 85
RMS dz = 117.051270818
100cm = 67.6795203706 percentile value of dz