curvature versus slope
  n = 629409 
  X=0, Y = 19.33 +/- 17.08 
  Weighted least-squares fit:  Y = 45.3 + 2.528 X  + -0.02747 X**2 

slope versus dZ, curvature < 5
  n = 56655 
  X=0, Y = 6.40 +/- 5.99 
  Weighted least-squares fit:  Y = 13.2 + 0.168 X  + 0.00205 X**2 
     at X = 100, Y = 50.5 
     effective RMSE xy = 76.6 

slope versus dZ, curvature < 15
  n = 128394 
  X=0, Y = 6.40 +/- 5.99 
  Weighted least-squares fit:  Y = 13.2 + 0.304 X  + 0.00112 X**2 

curvature versus dZ, slope < 10
  n = 48786 
  X=0, Y = 13.16 +/- 10.31 
  Weighted least-squares fit:  Y = 12.8 + 2.566 X  + -0.04597 X**2 


Number of samples 636609
Max dz = 900
Mean dz = 51
RMS dz = 76.6615940351
100cm = 84.2746489604 percentile value of dz