The edges of the room and the corners give us all the information we need to construct where the floor might be and how to properly draw her in perspective. I won't go into too much detail since it would take an eternity to write.
Basically, we assume that the box she's in, has parallel walls. With this, you draw the lines (yellow and light blue). Using the knowledge available in books on perspective, you can determine the horizon line, and even figure out how exactly tall she is. In this case, she took the picture and cropped it, which is why i drew overall image is not centered within the circle. But yes... This is 3 point perspective. If you wanted to draw her feet in, you couldn't really do that unless you switched to fisheye perspective and not have it look wonky. The point I was trying to make here >>5322142
is that once you learn perspective on a basic level, you will become quicker and foreshortening and understanding how to do it accurately. Make good habits early.