GraVVITAS: accessible graphics for visually impaired people

Graphics, whether they are visually appealing elements or simply scribbles on a sheet of paper, are important tools used by people to convey information. They are widely used in educational and daily life materials such as newspapers, text books, web pages, electronic books, metro maps, instruction manuals etc. When appropriate they provide many cognitive benefits over text. Graphics are also becoming more sophisticated with recent advances in information visualisation applications, and now often include dynamic content such as animations and elements that can interact with the users. Unfortunately, graphics are not easily accessed by visually impaired people, in partic- ular by blind people. There have been many different approaches to solve this problem by using tactile, tactile-audio, haptic and speech/non-speech audio techniques, however, these approaches have limitations such as use of expensive tactile graphics or expensive peripheral devices, and they may not provide similar cognitive benefits to visual graphics. The main contribution of this thesis is GraVVITAS (Graphics Viewer using Vibra- tion, Interactive Touch, Audio and Speech) which addresses these limitations and presents graphics to blind people in a way which: (i) can be used effectively to read accessible versions of a wide range of graphics while preserving the cognitive benefits of visual graphics, (ii) is practical in terms of cost and portability, and (iii) provides an interactive display which allows dynamic exploration of graphics. A user- centered and participatory design methodology is used to develop GraVVITAS. A usability evaluation is then performed to investigate the interaction model of the final system. In addition to GraVVITAS the thesis has the following contributions: (i) an evaluation of assistive technologies used for presenting graphics to blind people by using theoretical analyses which assess the usability of these technologies, and to what extent they provide the cognitive benefits of graphics, (ii) a formal usability study which examines tactile and tactile-audio bar chart layouts for improving their effectiveness and readability, (iii) authoring tools developed to create accessible graphics.