If I found my roommate set a mini surveillance camera in our room and she didn't tell me before, is that invasion of privacy?

It is a clear invasion of privacy as the area is not easily seen by someone passing by and you have an expectation of privacy, especially since you are a woman and there are web sites that post pictures of women not fully dressed. Talk to her as to why she set up the camera and why she did not tell you, that she must immediately remove it and show you it has been disposed of so she can not use it again, she has to turn over to you all photos, video from the camera, ask who she distributed any images to, etc. if she refuses to fully co-operate, report her to the dean for students and demand she be moved out of your room.