curvature versus slope
  n = 611784 
  X=0, Y = 6.98 +/- 5.96 
  Weighted least-squares fit:  Y = 11.6 + 4.805 X  + -0.05593 X**2 

slope versus dZ, curvature < 5
  n = 381197 
  X=0, Y = 10.44 +/- 6.72 
  Weighted least-squares fit:  Y = 10.7 + 0.193 X  + 0.00286 X**2 
     at X = 100, Y = 58.7 
     effective RMSE xy = 90.6 

slope versus dZ, curvature < 15
  n = 493368 
  X=0, Y = 10.75 +/- 6.93 
  Weighted least-squares fit:  Y = 10.6 + 0.311 X  + 0.00206 X**2 

curvature versus dZ, slope < 10
  n = 417111 
  X=0, Y = 10.89 +/- 6.57 
  Weighted least-squares fit:  Y = 10.7 + 1.450 X  + 0.08482 X**2 


Number of samples 619276
Max dz = 900
Mean dz = 20
RMS dz = 54.9909083395
100cm = 96.8679554835 percentile value of dz