A shot seen so many times. Why do variations of this image have such appeal?
Because of its absolute simplicity.
Firstly, it is a completely anonymous "everywoman" portrait of legs.
Secondly, the shapes and curves remain absolutely feminine. We would respond to those forms even if it were a simple line drawing.
Thirdly, because it is strongly sexually symbolic. The bent leg acting as symbolic penis and discrete covering at the same time.
The image has to be central and the pose well held,
There must be no tilt to the upthrust leg.
The legs should have the slight overlap so that the outer lines of both legs run smoothly through each other.
The model is lying on a reflective perspex sheet. That gives the reflection at the base of the picture.
This is really important. Without it, the body would just be floating in space. Instead, the reflection clearly grounds the figure. Graphically speaking it provides a plinth from which the sculptural legs extend.
This is an excerpt from "Art Nude Photography Explained" which shows you how to create nude images and how to read and evaluate art nude photographs
It is available on Amazon