curvature versus slope
  n = 82341 
  X=0, Y = 20.69 +/- 16.05 
  Weighted least-squares fit:  Y = 51.0 + 2.163 X  + -0.02278 X**2 

slope versus dZ, curvature < 5
  n = 9737 

  Weighted least-squares fit:  Y = 7.2 + 0.349 X  + -0.00025 X**2 
     at X = 100, Y = 39.6 
     effective RMSE xy = 61.1 

slope versus dZ, curvature < 15
  n = 16231 

  Weighted least-squares fit:  Y = 7.4 + 0.359 X  + 0.00068 X**2 

curvature versus dZ, slope < 10
  n = 4882 
  X=0, Y = 10.48 +/- 5.36 
  Weighted least-squares fit:  Y = 10.4 + -0.020 X  + 0.22331 X**2 


Number of samples 82730
Max dz = 900
Mean dz = 52
RMS dz = 117.511701545
100cm = 86.9563640759 percentile value of dz