Apparently, when using 3D virtual space to explore design
approaches, people expect to be able to draw sketches and
add figures and memos to the virtual 3D space. For instance,
people need to draw arrows or sketches to indicate their
notes and changes to a plan or VR content in a collaborative
design work. Thus, annotation can be defined as freehand
sketching and annotated text in a 3D virtual space in the
context of this paper