curvature versus slope
  n = 365105 
  X=0, Y = 8.12 +/- 3.64 
  Weighted least-squares fit:  Y = 8.0 + 0.697 X  + 0.00186 X**2 

slope versus dZ, curvature < 5
  n = 230155 
  X=0, Y = 10.65 +/- 6.41 
  Weighted least-squares fit:  Y = 10.7 + -0.036 X  + 0.00732 X**2 
     at X = 100, Y = 80.3 
     effective RMSE xy = 125.0 

slope versus dZ, curvature < 15
  n = 340340 
  X=0, Y = 16.86 +/- 13.19 
  Weighted least-squares fit:  Y = 11.5 + 0.008 X  + 0.00641 X**2 

curvature versus dZ, slope < 10
  n = 278591 
  X=0, Y = 9.93 +/- 6.37 
  Weighted least-squares fit:  Y = 9.8 + 1.655 X  + 0.03776 X**2 


Number of samples 365123
Max dz = 300
Mean dz = 10
RMS dz = 12.7671453348
100cm = 99.9953440347 percentile value of dz