curvature versus slope
  n = 373197 
  X=0, Y = 13.69 +/- 10.86 
  Weighted least-squares fit:  Y = 18.0 + 4.370 X  + -0.04944 X**2 

slope versus dZ, curvature < 5
  n = 202133 
  X=0, Y = 6.52 +/- 3.96 
  Weighted least-squares fit:  Y = 6.0 + 0.270 X  + 0.00085 X**2 
     at X = 100, Y = 41.5 
     effective RMSE xy = 64.5 

slope versus dZ, curvature < 15
  n = 283080 
  X=0, Y = 6.68 +/- 4.08 
  Weighted least-squares fit:  Y = 6.0 + 0.299 X  + 0.00082 X**2 

curvature versus dZ, slope < 10
  n = 184733 
  X=0, Y = 7.22 +/- 4.62 
  Weighted least-squares fit:  Y = 6.4 + 1.449 X  + 0.04477 X**2 


Number of samples 377737
Max dz = 900
Mean dz = 14
RMS dz = 28.7576076891
100cm = 98.660443642 percentile value of dz