1. A method performed by a control unit (CU) for aligning two or more video image frames received from two or more video cameras at an endpoint, the endpoint communicably connected to the CU via a communication network, comprising: receiving two or more reference image frames from the endpoint; and determining two or more reference points, each reference point located in at least two of the two or more video image frames, the two or more reference points derived from location coordinates of a same spot of a projected reference image captured in the two or more reference image frames.