  Virtual Reality (VR) applications often require users to perform actions with
two hands when performing tasks and interacting with objects in virtual
environments. Although bimanual interactions in VR can resemble real-world
interactions -- thus increasing realism and improving immersion -- they can
also pose significant accessibility challenges to people with limited mobility,
such as for people who have full use of only one hand. An opportunity exists to
create accessible techniques that take advantage of users' abilities, but
designers currently lack structured tools to consider alternative approaches.
To begin filling this gap, we propose Two-in-One, a design space that
facilitates the creation of accessible methods for bimanual interactions in VR
from unimanual input. Our design space comprises two dimensions, bimanual
interactions and computer assistance, and we provide a detailed examination of
issues to consider when creating new unimanual input techniques that map to
bimanual interactions in VR. We used our design space to create three
interaction techniques that we subsequently implemented for a subset of
bimanual interactions and received user feedback through a video elicitation
study with 17 people with limited mobility. Our findings explore complex
tradeoffs associated with autonomy and agency and highlight the need for
additional settings and methods to make VR accessible to people with limited
mobility.
