Consider the diagram of a pinhole camera below, with camera…
Consider the diagram of a pinhole camera below, with camera coordinate system in blue and sensor coordinate system in red. To simplify, we’ll assume (i) the origin of the sensor coordinate system lies along the optical axis, (ii) the units of the sensor and camera coordinate systems match (both are in centimeters, say), and (iii) the location of the image plane is at zc=+1.0. If xc is a point in the camera’s coordinate system, its projection onto the image plane is given by the formula (circle one):