I have the following diagram that describes a camera model (I believe it is the pinhole camera model).
For example, an image plane is described as follows
that plane in the world which is identified with the plane of the display monitor used to view the image that is being rendered
So, is the image plane just the plane of the camera (or phone, etc.) where the image is displayed?
The virtual image is defined as
In optics, an image is defined as the collection of focus points of light rays coming from an object. A real image is the collection of focus points actually made by converging rays, while a virtual image is the collection of focus points made by extensions of diverging rays. In other words, a virtual image is found by tracing real rays that emerge from an optical device (lens, mirror, or some combination) backward to perceived or apparent origins of ray divergences.
In the diagram above, there are rays coming from the object. The description above seems to be consistent with the virtual image (i.e. the imaginary plane between the pinhole of the camera and the actual 3d real object) in the diagram above.
Because the rays never really converge, a virtual image cannot be projected onto a screen. In contrast, a real image can be projected on the screen as it is formed by rays that converge on a real location.
What the heck is a real image in the diagram above?
After all these conclusions, I still don't get the whole picture (pun intended). What is an image plane? What is a virtual image? What are their differences? What are their purposes?