Research on Accessing Graphics

Accessing Maps, Diagrams, and similar Object-Oriented Graphics


There are a number of audio technologies that are useful as substitutes or enhancements for visual presentation of maps, charts, diagrams, and other types of object-oriented graphical information. Many of these technologies rely on feeback from the computer to identify and display information about the important objects in the figure.

For example, Jacobson and Kitchin reported that blind people can read" maps rather well by using a touch screen and running their fingers along a road or railroad track, interrogating cross streets as they are encountered, etc. This "map-reading" method requires not only a touch screen but also graphics software that can provide information to the viewer about any major object on the screen. In this case the names of streets, railroads, foot- and bike-paths, etc.

This access method relies on the user's ability to assimilate a mental spatial image of the map. A tactile image greatly reduces the mental effort, and this combination of touch and audio(or braille) feedback has been found to be very successful in making maps and other graphics accessible to blind users. See Parkes reference.

There are no technologies for displaying refreshable tactile images on-line, but it is possible to create a tactile copy of a computer picture. See Gardner review Tactile Graphics: an Overview and Resource Guide for the state-of-the-art in 1996. The newly-introduced Tiger Tactile Graphics and Braille Embosser greatly enhances possibilities for creating and distributing tactile graphics.

A tactile figure on a touch screen or other digitizing tablet permits a blind user to feel the tactile images, and receive audio feedback from the computer about those images.

The critical necessity for any of these methods to work is a well-structured data format that includes labels and permits other information about objects and the location of these objects in the figure.

The SAP developed methods for permitting this kind of information to be added and displayed for bit map web graphics. on the world wide web. These graphic files are accessible to blind users through a touch screen (or any digitizing tablet that acts as a mouse). Better access is achieved if a tactile picture is put on the touch pad.

This research phase on bit-map graphics was successful in developing understanding of audio/tactil access possibilities and limitations, but there is no way to make bit map graphics that are more-or-less automatically accessible. A separate "accessibility" page needs to accompany each graphic. Scalable Vector Graphics (SVG) appears to be a major graphics language of the future and has now become our center of attention.

An SVG graphic is an object-oriented file for which each object has a label and description field. It has enormous potential as an improved method for displaying the kinds of information scientists love to show without the need to clutter figures with vast numbers of explanatory labels. The good structure and availability of label and description fields make SVG an ideal file for audio-graphic display as well. We are now developing a audio/tactile/haptic SVG browser that can provide excellent access to graphical information by everybody, including people with print disabilities. The SVG project is described in a paper in the 2001 CSUN conference. People with the ability to use the mouse can access labels and object descriptions by a click of the mouse. Those who cannot see the screen or who cannot process the visual information can "view" the graphic either with an on-line haptic device or through a tactile graphic picture that has been created and placed on a digitizing pad. Haptic access is useful but too limited to give adequate access to more complex graphics. Any student who needs tactile copy for access can achieve that if her/his institution has a Tiger available in a university computer lab. You may Download the current SVG Accessible Viewer to try a few examples. This download is put up largely to assist people who are using SVG to make their files accessible. It will be a year or two before a final version of the viewer will be available, and we are encouraging all SVG users to assure that their sites will be accessible when the time comes. The zip files contains a brief "read-me.txt" file that explains how to use the Viewer.

We have also experimented with Virtual Reality Modeling Language (VRML) as a graphics language. VRML is a high-level well-structured language permitting very flexible modeling of three dimensional time-dependent interactive graphics. There are several research efforts, at the University of Toronto, and at NIST, aimed at making VRML more accessible by non-visual means.

Although VRML is not intrinsically fully accessible, it it is a language capable of representing graphical information in a form that is at least in principle fully accessible. Until the advent of SVG there was no other common graphical language with this capability.

We have constructed some prototype examples of VRML graphics that are interactive, and one is time-dependent. They contain everything necessary for accessibility by people who cannot see.

All objects in these example files have "hidden" labels that can be inspected by clicking on the object and popping up a dialog box containing the label and any other information an author might want to include. This is the only "special" addition that is required in principle for full accessibility. Other features that permit good audio and haptic access, etc. should eventually be included automatically by good authoring tools. Object labels will be useful to many people other than those with print disabilities, and we anticipate that all authors will find it advantageous to use object labels. If so, all figures would be accessible to all people.

Special audio display tools analogous to our audio graph browser should eventually permit a range of audio display options. Such tools are not presently available, and the information necessary for their use is not included in any standard way at present however. Therefore we have added audio features to these prototype examples to illustrate what could be possible with such future tools.

Finally we remark that access to the interactive and time-dependent features of these figures should be vastly improved with force feedback devices like the haptic mice discussed earlier.


Reference R. Jacobson and R. Kitchin,

"Geographical information systems and people with visual impairments or blindness: Exploring the potential for education, orientation and navigation"
Transactions in Geographical Information Systems, 2(4) 315-332 (1997)

Reference D. Parkes
"NOMAD": AN AUDIO-TACTILE TOOL FOR THE ACQUISITION, USE AND MANAGEMENT OF SPATIALLY DISTRIBUTED INFORMATION BY PARTIALLY SIGHTED AND BLIND PERSONS"
Editors. A. F. Tatham and A. G. Dodds
Proceedings of the Second International Symposium on Maps and Graphics for Visually Handicapped People
King's College, University of London, April 20-22 1988, pp. 24-29



Last update March 12, 2002