curvature versus slope
  n = 175404 
  X=0, Y = 13.09 +/- 11.07 
  Weighted least-squares fit:  Y = 22.8 + 3.798 X  + -0.04233 X**2 

slope versus dZ, curvature < 5
  n = 69795 
  X=0, Y = 14.48 +/- 6.98 
  Weighted least-squares fit:  Y = 11.9 + 0.067 X  + 0.00141 X**2 
     at X = 100, Y = 32.6 
     effective RMSE xy = 47.7 

slope versus dZ, curvature < 15
  n = 107512 
  X=0, Y = 14.48 +/- 6.98 
  Weighted least-squares fit:  Y = 12.0 + 0.126 X  + 0.00130 X**2 

curvature versus dZ, slope < 10
  n = 78504 
  X=0, Y = 12.70 +/- 6.36 
  Weighted least-squares fit:  Y = 12.2 + 1.053 X  + 0.00897 X**2 


Number of samples 177130
Max dz = 900
Mean dz = 23
RMS dz = 56.1960852729
100cm = 96.6956472647 percentile value of dz