No! That's not obscene at all! Not in my book, anyway: to me, obscenity involves portaying images that are exploitative or offensively gross in some way, sexually tacky, or something like that. It's very difficult to define, and there's certainly no blanket like 'if it contains nudity, it's obscene' much though some serious prudes would like to think. Using the human body-- which in itself is NOT obscene, not in the slightest-- to illustrate an idea is as old as art itself, and the naked human body is an object of beauty as much as it can be made an object of obscene stuff. Personally I think your work is very powerful and expressive and it would seriously detract from it if you put underwear on the models! And as Sam (my boyfriend, here just now) says, the nudity of the figures "is certainly not what you first notice".