curvature versus slope
  n = 116175 
  X=0, Y = 21.19 +/- 20.03 
  Weighted least-squares fit:  Y = 66.2 + 1.582 X  + -0.01585 X**2 

slope versus dZ, curvature < 5
  n = 6471 

  Weighted least-squares fit:  Y = 8.1 + 0.161 X  + 0.00080 X**2 
     at X = 100, Y = 32.2 
     effective RMSE xy = 49.0 

slope versus dZ, curvature < 15
  n = 13625 

  Weighted least-squares fit:  Y = 7.5 + 0.335 X  + 0.00056 X**2 

curvature versus dZ, slope < 10
  n = 6935 
  X=0, Y = 9.12 +/- 5.08 
  Weighted least-squares fit:  Y = 9.1 + 0.701 X  + 0.13708 X**2 


Number of samples 118312
Max dz = 900
Mean dz = 59
RMS dz = 90.7248587764
100cm = 81.3983366015 percentile value of dz