Design guidelines for an interactive 3D model as a supporting tool for exploring a cultural site by visually impaired and sighted people

Being able to explore and familiarise themselves with the structure and details of a cultural site before actually visiting it is fundamental for orienting visually impaired people during the visit; otherwise, it is particularly difficult to gain a global understanding of the structure and an overall impression of a square, a church, or a large monument. Our project addressed this problem by using low cost 3D models combined with audio descriptions to enable visually impaired users to explore the cultural site autonomously. Audio descriptions are organised into three groups (for historical, practical, and architectural information), and for each group, several tracks are recorded giving increasing levels of details. Users can easily navigate through the audio tracks to follow their tactile exploration by listening to the information they are most interested in. Relevant details are reproduced separately and linked to the main model via the audio tracks. A goal of our model is to enhance the understanding of the cultural site also for partially sighted as well as sighted people, making them able to appreciate the details of the architectural design using both visual and auditory senses. We exploited low-cost and partially open-source technologies, thus rendering our system easily replicable. We evaluated the interactive system with blind, partially sighted, and sighted users. Our user test confirmed the validity of our approach: (1) the 3D models and the tactile reproduction of details obtained via a low-cost 3D printing solution are well perceived by touch; (2) the semantic auditory information activated via perceptible buttons on demand and the different content levels for the audio tracks are suitable for an interactive, autonomous, and satisfying exploration; and (3) relevant details are well perceived. Finally, we propose guidelines to use in the 3D reproduction of buildings or large sites based on our experience.