To easily capture the light emission position of a light-emitting apparatus on the imaging apparatus side, even when the positional relationship of the two changes. A mobile device detects its own speed, and an LED within the mobile device accomplishes light emission in accordance with any out of a first light emission pattern, a second light emission pattern and a third light emission pattern so that the light emission cycle becomes shorter the faster the speed of the mobile device. On the other hand, a server detects the speed of the mobile device from frames obtained through imaging by an imager, and changes the imaging interval of the imager so that the imaging interval becomes longer the slower the speed.