Visualisers or document cameras are a great teaching aid. They are especially useful when you have to make a presentation to a class in a large room. This means they are perfect for lecture theatres.
Most university classes are taught in large lecture theatres rather than classrooms. For this reason audio visual equipment has to be used to ensure that the whole classroom can hear the professor. Most lecturers have to use visual aids at some point and need to use audio visual equipment so that the room can see those visual aids. For sharing visual aids with a large class document cameras are the best AV aid there is.
Document cameras can display 3D objects, so it is possible to display an object from all angles. You can even physically carry out an experiment or make something from scratch under a document camera. That way the whole class can be shown an item or a procedure in detail. Not even students at the back of the lecture studio are going to miss anything.
The overhead projector was the forefather of the document camera, but it had a lot of limitations. Document cameras are compatible with many other audio visual devices. This means that if you have a video you want to show your class you can just plug your video camera into the document camera and show the whole class your video.
Connected to the right equipment document cameras can be used to present a lecture remotely. They are used in this way by the business community as well as by schools, colleges and universities.
The fact that document cameras can be used to present information in such a startling and full way is what makes them so great. If you do want to present something like a book or anything else on paper to your class you can. In these situations document cameras work in exactly the same way as overhead projectors.