Camera Height for Dramatic Effect

Camera height can give a subtle yet dramatic feeling to the viewer. Since our perspective is from that of the camera, we automatically associate ourselves with it.  A higher camera than the subject means we are looking down on that person, and we will feel more powerful as a result. A lower camera puts the viewer in a vulnerable position and looking up will usually show the subject as being more powerful. However, if the context is suspenseful, we will also see less far and our perspective will be unnervingly skewed.

In these examples, from the Alien franchise, a high camera will give a sense that we (the Alien) are bigger and watching them, and that the subject is powerless and/or unaware of our presence. It's quite unnerving for the subject (who we hopefully care about). A higher camera will also have the effect of limiting the view around the subject, which in itself is suspenseful.

Conversely, here's some examples where the camera is low. Usually this gives the impression the subject is in control, but in Alien it is meant to feel unnerving, to hide the view around the subject and to make the viewer feel more vulnerable.