I am new to computer vision and was watching this lecture on camera calibration. I will use a diagram from the lecture for reference.
From what I understand, a ray of light that is emitted from a point in 3D space (in the world coordinate frame) will pass through the aperture that is the pinhole and hit the image plane, creating a singular pixel. However, why do we need to find the position of the point in the world coordinate with respect to the camera coordinate frame? Can we just disregard the camera coordinate frame entirely and just use similar triangles to find the image coordinates directly?