Given a projection matrix m, it’s null space is the camera center.
Why? Because every point on a specific ray that is projected through projection line of the camera center has to land on the same spot on the image, so that means that the camera matrix times the center point must be equal to 0 in order for the projections to land on the same line regardless of scale.
Formula= MC = 0
Which is equal to:
C = [-Q¯¹b ][ 1]
