curvature versus slope
  n = 268546 
  X=0, Y = 9.95 +/- 7.47 
  Weighted least-squares fit:  Y = 11.7 + 4.248 X  + -0.04604 X**2 

slope versus dZ, curvature < 5
  n = 108443 
  X=0, Y = 9.22 +/- 7.59 
  Weighted least-squares fit:  Y = 13.3 + 0.230 X  + 0.00077 X**2 
     at X = 100, Y = 44.1 
     effective RMSE xy = 66.1 

slope versus dZ, curvature < 15
  n = 197780 
  X=0, Y = 12.41 +/- 10.29 
  Weighted least-squares fit:  Y = 13.3 + 0.272 X  + 0.00039 X**2 

curvature versus dZ, slope < 10
  n = 152542 
  X=0, Y = 15.61 +/- 11.42 
  Weighted least-squares fit:  Y = 14.1 + 0.584 X  + 0.11116 X**2 


Number of samples 274375
Max dz = 900
Mean dz = 19
RMS dz = 35.7910603363
100cm = 97.6586788155 percentile value of dz