1. An imaging parameter acquisition apparatus connected via a network to a client system equipped with a display apparatus and imaging apparatuses, the imaging parameter acquisition apparatus comprising: a movement instruction unit that sends a moving instruction message to the client system, the moving instruction message instructing to move the display apparatus so that each of the imaging apparatuses, which define lines of sight for creating a three-dimensional model, can shoot a screen of the display apparatus; a pattern image display instruction unit that sends a display instruction message to the client system to which the moving instruction message is sent, the display instruction message instructing the display apparatus to display a pattern image for imaging parameter calculation; an imaging instruction unit that sends an imaging instruction message to the client system to which the display instruction message is sent, the imaging instruction message instructing the imaging apparatuses to shoot the screen of the display apparatus; an image acquisition unit that acquires images which are shot by the imaging apparatuses in response to the imaging instruction message; an imaging parameter acquisition unit that acquires imaging parameters of each of the imaging apparatuses based on the images acquired by the image acquisition unit; and a memory unit that stores the imaging parameters acquired by the imaging parameter acquisition unit, wherein the memory unit stores, in association with each of client systems connected via the network, each of the imaging parameters of the imaging apparatuses included in each of the client systems, the imaging parameters being acquired by the imaging parameter acquisition unit.