Is 你是哪个人 the correct way to ask where you are from in China?
No, "你是哪个人" doesn't make much sense here. It translates into "Which one you are?".

Instead, you shall say "你是哪里人" as you have put.

If you are looking at the picture and you cannot recognize which one is your friend. You will probably ask "哪个人是你" literally means "Which one (in the picture) is you?"