How does a HUD track a runway? I was looking at the FCOM of the 787, and I came across an interesting thing. There is an HUD takeoff selection on the SID selection page. It got me to wonder, how does the HUD track the runway from so far away?

Is it related to ILS?
Correct, that optional feature on the 787 relies on the ILS or GLS signals.


  On takeoff, HUD provides lateral guidance for takeoff roll and rejected takeoff using ILS or GLS signals.


(FCOM 4.20.7)

PVD (Para-Visual Display) is a similar instrument (in function) that was available on the 747-400 as an option that relied on the ILS (shown below).


(aerowinx.com) PVD.



Further reading:


Peripheral Vision Displays (nasa.gov).
The crash of Singapore Airlines Flight 006 during a takeoff in LVP conditions.