curvature versus slope
  n = 825155 
  X=0, Y = 16.43 +/- 15.70 
  Weighted least-squares fit:  Y = 45.7 + 2.597 X  + -0.02852 X**2 

slope versus dZ, curvature < 5
  n = 108452 
  X=0, Y = 16.78 +/- 9.16 
  Weighted least-squares fit:  Y = 15.3 + 0.085 X  + 0.00396 X**2 
     at X = 100, Y = 63.4 
     effective RMSE xy = 96.7 

slope versus dZ, curvature < 15
  n = 238319 
  X=0, Y = 16.78 +/- 9.16 
  Weighted least-squares fit:  Y = 14.0 + 0.267 X  + 0.00262 X**2 

curvature versus dZ, slope < 10
  n = 79276 
  X=0, Y = 16.65 +/- 8.68 
  Weighted least-squares fit:  Y = 16.4 + 0.223 X  + 0.14193 X**2 


Number of samples 833376
Max dz = 900
Mean dz = 47
RMS dz = 73.1436941916
100cm = 87.5824357793 percentile value of dz