Image projection system, pointing element, and method for controlling image projection system

An image projection system comprising:

• a projector;
• and
• a pointing element, wherein
• the projector includes
• an image projection unit which projects an image;
• an image pickup unit which performs image pickup in a first period and does not perform image pickup in a second period, the first period and the second period being periodically repeated;
• a detection unit which detects a pointed position of the pointing element, based on an image picked up by the image pickup unit;
• and
• a receiving unit which receives pointing element information transmitted from the pointing element,
• the pointing element includes
• a light emitting unit;
• a control unit which controls light emission of the light emitting unit;
• and
• a storage unit which stores the pointing element information,
• the control unit of the pointing element causes the light emitting unit to perform first light emission in the first period and causes the light emitting unit to perform second light emission corresponding to the pointing element information in the second period,
• the detection unit of the projector detects the pointed position, based on an image of the first light emission picked up by the image pickup unit, and
• the receiving unit of the projector receives the pointing element information transmitted via the second light emission.