Camera matrix

In computer vision a camera matrix or camera projection matrix is a $3\times 4$ matrix which describes the mapping of a pinhole camera from 3D points in the world to 2D points in an image.

Let $\mathbf {x}$ be a representation of a 3D point in homogeneous coordinates, and let $\mathbf {y}$ be a representation of the image of this point in the pinhole camera. Then the follwing relation holds

\mathbf{y} \sim \mathbf{C} \: \mathbf{x}

where $\mathbf {C}$ is the camera matrix.