How to deal with petty vindictive people?

There is a girl at work who for some reason has taken an intense dislike to me, I think its because I don't go drinking with her circle of losers, (I don't drink or smoke). I don't really mind but in the office out of obligation she has to interact with me, but when I see her outside the building, normally with a cigarette in her mouth she just rudely ignores me. She has a heightened opinion of hersef because of her large which are much admired in the company, (not my type really), and she is white (21years old). I am ethnic and not I would say average looking.Whenever I p her on the street I try to say hello out of politeness and she just looks the other way, making me feel very uncomfortable. As much as I don't like to admit it her behaviour is obviously bothering me now since I am writing this, has she got to me, what should I do? don't say ignore her, I don't want to sink to the level of that ameba and her friends.