Method for capturing real-world information into virtual environment and related head-mounted device

A method for capturing real-world information into a virtual environment is provided. The method is suitable for a head-mounted device (HMD) located in a physical environment, and includes the following operations: providing the virtual environment, wherein a real-world content within the virtual environment is captured from a part of the physical environment corresponding to a perspective of the HMD; tracking a feature point which located within the physical environment and moved by a user, so as to define a selected plane of the real-world content by projecting a moving track of the feature point onto the real-world content; capturing image information corresponding to the selected plane; and generating a virtual object having an appearance rendered according to the image information, in which the virtual object is adjustable in size.