Abstract |
The recent abundance of Extended Reality (XR) technologies has transformed the way we
perceive and interact with digital information. XR spans along the reality-virtuality continuum
permeating diverse sectors, from entertainment and gaming to education, healthcare, and
industry. As XR continues to gain widespread acceptance, it has become increasingly clear that
this innovative paradigm holds the potential not only to redefine our digital experiences but
also to impact the way we engage with technology itself. However, amidst the excitement and
promise of XR, digital accessibility is a crucial issue that demands our prompt attention. More
specifically, in the current rapidly evolving technological landscape, it is essential to prioritize
accessibility as a fundamental aspect of XR development. This necessitates a shift in current
practices toward a proactive commitment to incorporating accessibility features from the
outset of XR projects, which is a concept referred to as "Accessibility by Design" within the XR
landscape. In this respect, XR becomes not only transformative, but also equitable and inclusive,
ensuring that every individual, regardless of their abilities, can harness its full potential.
The concept of Accessibility by Design is stemming from the Universal Access and Design for All
principles, advocating the importance of catering for the needs of all individuals, including
persons with disabilities, at design time, avoiding a posteriori adaptation to products or services
to make them accessible. In the context of XR, this approach takes on particular significance,
especially considering that despite the fact that XR is still an emerging field, the discussion on
accessibility has already yielded guidelines that should be adhered to for the development of
accessible user experience. Furthermore, as a result of these efforts, XR technologies have
shown great promise in developing tools to assist users with visual impairments. These tools
focus on assisting users with visual impairments in interacting with the XR environment through
basic assistive functionalities, such as zoom-in, text enlargement, as well as the provision of
alternative input and output modalities. Nevertheless, despite considerable progress, most of
these initiatives remain proprietary software solutions, often limited to the research prototype
phase. The seamless integration of these solutions into mainstream XR applications or platforms
remains an open challenge, mainly due to the lack of generic and cohesive approaches
promoting accessibility across platforms in a consistent manner.
This thesis introduces a methodological accessibility framework and pertinent software tools
for the development of inclusive Extended Reality (XR) applications, following the ‘Accessible
by Design’ approach. The framework, built upon XR accessibility guidelines, best practices, and
cutting-edge techniques, addresses the needs of individuals with disabilities, with a primary
focus on blind and partially sighted users. Key features include customizable text settings,
alternative text on visual elements, multiple user interaction controls, edge enhancement for
visual elements, audio description of the visual elements, hierarchical navigation, foreground
positioning of active objects, and adaptable scene configurations. Furthermore, it allows the
enhancement of XR elements with haptics, providing force and temperature feedback, aiming
to augment users’ perception with additional information, allowing for example developers to
realistically represent virtual elements by imparting information about their physical
characteristics in the real world. The proposed framework was built following a human-
centered design approach, with the active involvement of individuals with vision impairments
and pertinent stakeholders in the requirements specification phase, as well as in its evaluation.
The proposed framework has been implemented as an assets package made on the Unity Game
Engine, available to be installed in XR applications.
To facilitate testing and evaluation, a Unity 3D sample scene was developed, using the
accessibility features of the framework. This scene presents a Virtual Reality (VR) museum,
showcasing different virtual rooms exhibiting 3D cultural heritage (CH) artefacts. In order to
assess the proposed framework, a user-based evaluation of the use-case VR museum was
carried out, involving 20 participants with vision impairments who assessed the system's
effectiveness, usability, mental workload, VR-induced sickness symptoms, and haptic
experience. The evaluation results demonstrate that the framework enhances the exploration
of VR environments, permitting users with vision impairments to efficiently navigate in the
environment and effectively perceive the museum exhibits, providing at the same time a
positive user experience without imposing undue cognitive load.
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