I'm a little confused about this diagram - how is the image point in between the camera center and the 3D world point? I'm confused about the positioning since this seems different from the pinhole camera setup, but correct me if I'm wrong.
motoole2
It's still a pinhole camera setup! The camera center is located at $C$, and it's looking at a world point $P^+ x$. Both $C$ and $P^+ x$ are defined with respect to the world coordinate system.
If we were to trace a ray through both $C$ and $P^+ x$, they intersect at a single point on the image plane. This intersection point is $x$, defined here with respect to the image coordinate system (e.g., it represents the coordinates of the pixel looking at the 3D point $P^+ x$). Note also that if we were to apply the camera matrix $P$ to the 3D point $P^+ x$, this produces $x$.
I'm a little confused about this diagram - how is the image point in between the camera center and the 3D world point? I'm confused about the positioning since this seems different from the pinhole camera setup, but correct me if I'm wrong.
It's still a pinhole camera setup! The camera center is located at $C$, and it's looking at a world point $P^+ x$. Both $C$ and $P^+ x$ are defined with respect to the world coordinate system.
If we were to trace a ray through both $C$ and $P^+ x$, they intersect at a single point on the image plane. This intersection point is $x$, defined here with respect to the image coordinate system (e.g., it represents the coordinates of the pixel looking at the 3D point $P^+ x$). Note also that if we were to apply the camera matrix $P$ to the 3D point $P^+ x$, this produces $x$.