curvature versus slope
  n = 74239 
  X=0, Y = 71.32 +/- 38.56 
  Weighted least-squares fit:  Y = 81.0 + 0.551 X  + -0.00477 X**2 

slope versus dZ, curvature < 5
  n = 754 

  Weighted least-squares fit:  Y = 0.9 + 0.786 X  + -0.00221 X**2 
     at X = 100, Y = 57.5 
     effective RMSE xy = 90.2 

slope versus dZ, curvature < 15
  n = 3663 

  Weighted least-squares fit:  Y = -1.1 + 0.994 X  + -0.00299 X**2 

curvature versus dZ, slope < 10
  n = 77 
  X=0, Y = 2.54 +/- 1.79 
  Weighted least-squares fit:  Y = 2.4 + 1.930 X  + 0.15987 X**2 


Number of samples 74891
Max dz = 800
Mean dz = 79
RMS dz = 115.442626443
100cm = 71.4665313589 percentile value of dz