A system for determining that a user is in possession of a game-ball comprising: a game-ball comprising an antenna and a response circuit; a user-worn device comprising a camera and a transceiver; and a computer system, wherein the transceiver is configured to: send, to the antenna of the game-ball, a radio frequency proximity signal; receive, from the antenna and the response circuit of the game-ball, a radio frequency return signal; and responsive to receiving the radio frequency return signal within a predetermined amount of time after sending the radio frequency proximity signal, sending a power up signal to the camera; and wherein the computer system is configured to: process first image data obtained from the camera worn by a first user; detect a presence of the game-ball within the first image data; determine a first image size of the game-ball; compare the first image size to a threshold image size; determine that the first user is in possession of the game-ball if the first image size meets or exceeds the threshold image size; and determine that the first user is not in possession of the game-ball if the first image size is less than the threshold image size. a game-ball comprising an antenna and a response circuit; a user-worn device comprising a camera and a transceiver; and a computer system, wherein the transceiver is configured to: send, to the antenna of the game-ball, a radio frequency proximity signal; receive, from the antenna and the response circuit of the game-ball, a radio frequency return signal; and responsive to receiving the radio frequency return signal within a predetermined amount of time after sending the radio frequency proximity signal, sending a power up signal to the camera; and wherein the computer system is configured to: process first image data obtained from the camera worn by a first user; detect a presence of the game-ball within the first image data; determine a first image size of the game-ball; compare the first image size to a threshold image size; determine that the first user is in possession of the game-ball if the first image size meets or exceeds the threshold image size; and determine that the first user is not in possession of the game-ball if the first image size is less than the threshold image size. send, to the antenna of the game-ball, a radio frequency proximity signal; receive, from the antenna and the response circuit of the game-ball, a radio frequency return signal; and responsive to receiving the radio frequency return signal within a predetermined amount of time after sending the radio frequency proximity signal, sending a power up signal to the camera; and wherein the computer system is configured to: process first image data obtained from the camera worn by a first user; detect a presence of the game-ball within the first image data; determine a first image size of the game-ball; compare the first image size to a threshold image size; determine that the first user is in possession of the game-ball if the first image size meets or exceeds the threshold image size; and determine that the first user is not in possession of the game-ball if the first image size is less than the threshold image size. process first image data obtained from the camera worn by a first user; detect a presence of the game-ball within the first image data; determine a first image size of the game-ball; compare the first image size to a threshold image size; determine that the first user is in possession of the game-ball if the first image size meets or exceeds the threshold image size; and determine that the first user is not in possession of the game-ball if the first image size is less than the threshold image size. <EOS>