curvature versus slope
  n = 1357979 
  X=0, Y = 17.37 +/- 15.27 
  Weighted least-squares fit:  Y = 35.3 + 3.493 X  + -0.03934 X**2 

slope versus dZ, curvature < 5
  n = 412669 

  Weighted least-squares fit:  Y = 8.3 + 0.209 X  + 0.00067 X**2 
     at X = 100, Y = 35.8 
     effective RMSE xy = 54.8 

slope versus dZ, curvature < 15
  n = 728932 

  Weighted least-squares fit:  Y = 8.3 + 0.282 X  + 0.00034 X**2 

curvature versus dZ, slope < 10
  n = 471862 
  X=0, Y = 8.96 +/- 5.92 
  Weighted least-squares fit:  Y = 9.0 + 1.095 X  + -0.01400 X**2 


Number of samples 1382947
Max dz = 900
Mean dz = 23
RMS dz = 40.286474157
100cm = 96.6327704532 percentile value of dz