1. A method, comprising: tracking, by a system comprising a processor via at least one sight line tracking device, at least sight lines of at least one eye of at least one user in a space; acquiring, by the system, sight line information of the at least one user in the space based on the tracking, wherein the sight line information comprises direction information, starting point information, and gaze point position information of the sight lines; and determining, at least according to the sight line information, at least one transparent object existing in the space.