curvature versus slope
  n = 442813 
  X=0, Y = 10.58 +/- 10.39 
  Weighted least-squares fit:  Y = 31.7 + 3.384 X  + -0.03866 X**2 

slope versus dZ, curvature < 5
  n = 119581 
  X=0, Y = 2.78 +/- 3.15 
  Weighted least-squares fit:  Y = 5.7 + 0.404 X  + 0.00067 X**2 
     at X = 100, Y = 52.8 
     effective RMSE xy = 82.4 

slope versus dZ, curvature < 15
  n = 168339 
  X=0, Y = 2.91 +/- 3.26 
  Weighted least-squares fit:  Y = 5.8 + 0.513 X  + -0.00048 X**2 

curvature versus dZ, slope < 10
  n = 114714 
  X=0, Y = 6.87 +/- 5.59 
  Weighted least-squares fit:  Y = 6.8 + 2.637 X  + -0.03868 X**2 


Number of samples 446102
Max dz = 900
Mean dz = 33
RMS dz = 66.1059755242
100cm = 93.28651295 percentile value of dz