curvature versus slope
  n = 406327 
  X=0, Y = 13.47 +/- 10.60 
  Weighted least-squares fit:  Y = 19.5 + 4.500 X  + -0.05356 X**2 

slope versus dZ, curvature < 5
  n = 215940 
  X=0, Y = 12.04 +/- 6.37 
  Weighted least-squares fit:  Y = 8.5 + 0.283 X  + 0.00124 X**2 
     at X = 100, Y = 49.2 
     effective RMSE xy = 76.1 

slope versus dZ, curvature < 15
  n = 290369 
  X=0, Y = 12.20 +/- 6.59 
  Weighted least-squares fit:  Y = 8.3 + 0.323 X  + 0.00098 X**2 

curvature versus dZ, slope < 10
  n = 182877 
  X=0, Y = 10.41 +/- 6.12 
  Weighted least-squares fit:  Y = 9.7 + 1.091 X  + 0.06421 X**2 


Number of samples 413589
Max dz = 900
Mean dz = 18
RMS dz = 32.4807635378
100cm = 98.0243671858 percentile value of dz