curvature versus slope
  n = 149969 
  X=0, Y = 53.04 +/- 27.53 
  Weighted least-squares fit:  Y = 58.8 + 1.373 X  + -0.01150 X**2 

slope versus dZ, curvature < 5
  n = 13718 

  Weighted least-squares fit:  Y = 11.9 + 0.198 X  + 0.00143 X**2 
     at X = 100, Y = 46.0 
     effective RMSE xy = 69.8 

slope versus dZ, curvature < 15
  n = 47258 

  Weighted least-squares fit:  Y = 13.2 + 0.226 X  + 0.00109 X**2 

curvature versus dZ, slope < 10
  n = 1863 
  X=0, Y = 17.71 +/- 9.67 
  Weighted least-squares fit:  Y = 16.2 + 1.247 X  + 0.05925 X**2 


Number of samples 151719
Max dz = 800
Mean dz = 36
RMS dz = 51.9037570894
100cm = 95.1482675209 percentile value of dz