Technical Drawings Understanding for the Blind

Our experience in local evaluations has reached scientific and technical sectors. As regards remote evaluations, we have obtained good results with users who could master computer instruments autonomously. As regards the material available for testing and evaluation, we have appreciated that it was well structured; this aspect was of the utmost importance during the evaluation phase. Moreover, we had frequent contacts over the phone with our users. It is worth to be mentioned that usually tutorials and manuals intended for local evaluations are not carefully drafted, since the physical presence of a human guide can do for the lack of completeness; on the contrary, exhaustive and complete manuals were prepared for remote evaluation and they revealed to be very important instruments for introducing the users into the system.

It was possible to learn a lot as for non-graphical interfaces for diagrams, especially as for three topics: - which information can be reported to help a blind to understand a diagram. For example as for floor plans it was useful to add descriptions of the shape of a room or about the number of doors and windows, etc. - what is better to vocally output or Braille output. It was found that vocal output helps a lot to quickly explore a diagram only when particular captions are vocally output (i.e. the name of the node when reached). More descriptive information, as the methods and attributes for a class in UML class diagrams, can be output on display Braille so that more attention can be paid to its content. - pros and cons of alternative output devices. The use of the joystick could bring great advantages especially to understand the positions of the nodes adjacent to a specific node. What was learnt as for non-graphical representations of diagrams can be useful also in the future (i.e. when describing a diagram aurally or to propose enhancements to screen reading software).

It was learnt very much above all as for vocal descriptions and exploration techniques. Vocal descriptions can be very short if properly planned. The techniques which were evaluated in the TeDUB system are a good basis also for teachers who have to describe a diagram both vocally and by means of tactile maps which show the structure of the diagram, but not its captions or the shape of its nodes.

Thanks to remote and face-to-face evaluations, and also thanks to discussions, which arose with export blind users, it was possible to better understand how blind people can make a mental image of a diagram. In particular some relevant considerations can be remarked: - as for simple diagrams without a great amount of written information and without many connections, blind persons prefer tactile representations. Actually simple tactile diagrams can be perceived by touch quickly and different parts (two nodes, two connections, a node and a connection, etc.) can be understood synchronously, likewise sighted persons can do by observing a diagram by sight; - as for complex diagrams (i.e. those diagrams that contain many captions and a great deal of connections and nodes) tactile representations aren't enough, therefore Braille and audio interaction is preferred. Audio and Braille exploration can't enable a blind to understand synchronously the diagram, but there are techniques to achieve synchronous exploration, namely the overall glance. These techniques were better understood during the project and they can be divided in two groups: - direct access to known or unknown parts of diagram (i.e. search node, select node from a list, etc.). The sighted exploration allows to directly finding a piece of information in a diagram. These techniques allow achieving the same purpose. - aggregation of nodes. The exploration by aggregating groups of nodes is a way to simplify a diagram so that the parts and their relations can be easily understood.

This is the Document Type Definition (DTD) of the internal XML format used to encode diagrams within and between TeDUB Diagram Navigator Module, Knowledge Processing Unit, Diagram Annotator Module, SVG import Process and the UML XMI import transformation.

The TeDUB Project has developed considerable knowledge about the kinds of information that visually impaired people would like from architectural plans and the ways they would like to interact with this information. This knowledge has application not only in the further development of the TeDUB and related systems, but also to the development of tactile and audio-tactile architectural plans for visually impaired people.

As for circuits, blind people seem not to take into account the spatial layout, but they pay attention mainly to the relations between gates and to the kind of gate. It is extremely relevant the use of aggregation because it helps to compute the result of a circuit. One more aspect of the utmost importance is the possibility to annotate intermediate results on out connections from gates. The exploration by joystick is very important with circuits above all as for quick explorations.

Knowledge of how experts in the domains studied by TeDUB (circuit diagrams, UML and floor plans) has been extremely useful in developing the current prototypes for the TeDUB system. This knowledge will continue to be used in the further development of the TeDUB system and in a variety of other projects undertaken by the partners, particularly in the areas of tactile diagrams and training for visually impaired people.

This is software that provides a means for blind people to read certain types of technical diagram using a screen reader and other equipment. Input into the system is through 'TeDUB' XML format and, for UML diagrams, some versions of the XMI interchange format. The software provides a representation of the diagram and support for domain-specific tasks in an accessible format. The primary information is presented to the blind user through the user's screen reader; additional information can also obtained by using low-cost joysticks. The software currently supports digital circuit diagrams, floor plans and most UML diagrams. It is the last of these in which the tool is most successful. The tool provides one of the very few ways through which blind people can gain access to technical information. We envisage it as being of most interest to blind people involved in software engineering; either as professionals and students. The tool will be made available for use free of charge.

The concept behind the knowledge-modelling unit is new from a scientific viewpoint. Its main concepts are: 1) A diagram is represented as a partonomic hierarchy. An element of the hierarchy represents a part of the diagram. Each part is defined in terms of its parts and the relations holding between them. The partonomic hierarchy can encompass an arbitrary number of semantic as well as geometric levels. 2) An assumed part is a hypothesis that is assigned a certain degree of confidence. Based on a mathematical model of confidence spreading, the best interpretation is inferred.

TeDUB offers an interface with which it is possible to navigate technical diagrams coming from the following tree domains: Architectural floor plans Circuit diagrams UML diagrams The interface is the result of an iterative process, based on extensive user studies in which potential end users of the software evaluated the suitability of the interface for reading these specific diagrams. Although the users initially have to get used to the joystick, the combination of the interface with the joystick, sounds and the screen reader works very well to give complete access to the content of these types of diagrams. The possibility to get an impression of the spatial lay out joystick of the diagrams by means of the joystick does not only help readers in representing the content, it facilitates contact with sighted users of the same diagrams. The TeDUB rationale and the developed interface is a good basis for giving access to any other type of box and pointer diagrams to visually impaired people.

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