Face login question

If i grow my hair longer than i have now will it not recognize my face? If the background is different well it accept my picture?? I am asking this stuff before i try the face login on my laptop. Also if i put the face recongnize program will i still need to put the login password thing can people bypass the face recognize program?
Answer #1
Face login usually tries to find the landmarks of your face, including eyes, nose, cheekbone and they act as reference points. A unique pattern is drawn between these reference points and is compared to the existing stored pattern.
If you were to cover any of the landmarks with something (eg. fake nose, hair covering eyes, large beard, etcetera), then the facial recognition system would fail to detect you and thus prevent you from logging in. Furthermore, some facial recognition systems allow you to login to the computer without any further password.
However, some systems can be tricked in to unlocking the PC by holding up a photo of you (or so I’ve heard). So it’s better to use a password anyway.