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Virtual human signing on the web
John Glauert, UEA ViSiCAST project manager, presents an overview of ViSiCAST, a project that has developed some flexible technology to provide access for deaf people in their chosen medium of sign language, to services currently provided only for hearing people, or in text. One in seven of the UK population is deaf or hard of hearing, but most have had some hearing in the past so can read well and may be able to lip-read. On the other hand, some 50,000 people have never heard speech and, as written language is closely linked to speech, they don't easily learn to read. Nevertheless many can communicate fluently using British Sign Language (BSL). Deaf people have their own rich culture, but lose many opportunities available to other members of society through lack of access to services. Unless interpretation in sign language is available, deaf people lose access to television, web and internet information, and to shops and other high street services. ViSiCAST The EU has funded a three-year programme involving nine partners in the UK, France, Germany, and the Netherlands to develop the use of Virtual Human Avatars in presenting sign language. The aim is to improve access to information when providing sign language interpreters would not be practical. UK partners are the ITC, Consignia, UEA (University of East Anglia) Norwich, Televirtual, and the RNID. ViSiCAST builds on earlier work in the UK: Simon the Signer, an experiment in generating automatic signing for broadcast, took words from the subtitle stream and used natural language processing techniques to present textual information as Sign Supported English, a simplified sign language familiar to most BSL users. TESSA is a prototype system to aid transactions between a deaf person and a Post Office clerk by translating the clerk's speech to sign language. A speech recogniser matches spoken phrases with a database of Post Office sentences. TESSA then presents the corresponding sequence of signs using a specially developed avatar. TESSA won the BCS Gold Medal and top IT Award in 2000, and has recently been on trial in a number of Post Offices around the country. Web applications ViSiCAST technology is also being developed for use on the web. An internet application provides up-to-date weather forecasts in text and national sign language for the Netherlands, Germany, and the UK. The user accesses the weather forecasts using a link to a web page on a server. The page displays a text version of the forecast with a pane showing Visia, the ViSiCAST avatar, and standard movie playing controls allow the signed version to be played, stopped, paused, and repeated. The text weather forecast uses phrases for all normal aspects of the weather (rain, visibility, temperature, and wind) for different areas and at different times. The structure is very similar to summary forecasts presented on the internet or through teletext. The system was designed around areas of the Netherlands, but is flexible as phrases such as 'north', 'south-east', 'in the whole country' can be used. The signed sequence involves the concatenation of individual sign phrases that correspond to the text phrases. The sentence order stays the same, but the sign order follows the correct structure for the national sign language concerned. In order to use the system the user must have a ViSiCAST avatar player plug-in for Internet Explorer on a Windows PC, developed by UEA and Televirtual. A set of sign files for the weather forecast sign phrases is required and would be distributed on CD for users without broadband internet connections. However, once the plug-in and signs are installed, the system can be used with a slow connection, as the page for a particular weather forecast is very compact. Signs are available for the three sign languages supported. Creating signed weather forecasts Weather forecasts must be constantly updated to be useful, so it is essential that signed forecasts can be generated easily and frequently. A Weather Forecast Creator application has been produced by UEA for use by meteorological organisations and others preparing internet content. The program is forms-based, with pulldown menus for building up a weather forecast from a sequence of weather phrases. Each phrase contains information about the time period and geographical area covered. Phrases can combine weather conditions and describe weather changes in time and in space. The interface can be in Dutch, English, or German. A forecast entered using the German text interface can be used to generate DGS signing, but since there is a common underlying model, the same forecast can be presented as English text with BSL signing, or as Dutch text with SLN signing. It takes only a few minutes to enter a comprehensive weather forecast and only seconds to generate all desired combinations of signed weather forecasts. The weather forecast creator is table driven from data held in XML files. The user interface labels and menu options match the language of the content creator. The user interface is in two sections. The top section lets the user choose a sentence type: general (including rain and cloud conditions), temperature (including thermometer readings), and wind (including wind force). Each of these dialogues enables the user to specify the time and place where a weather condition applies. The time can be a single specified time (such as: 'today', 'in the night') or a range of times (such as: from 'tonight' to 'tomorrow afternoon'). Similarly, the place can be a single place (such as: 'in the south', 'Zeeland') or a combination. The format is flexible enough to handle all but the most complex forecasts. The bottom section lists the sentences already created with buttons to allow new sentences to be added and previous sentences to be edited and reordered. Sentences are held in XML according to a language-independent model reflecting the logical structure of weather forecast information. For different sign languages the order of signing will vary, so the common model is transformed using XSLT (Extensible Stylesheet Language Transformations) to yield specific versions for each language. There is a live trial of the system in the Netherlands at www.dovenschap.org and there are plans to provide a UK version hosted by the RNID. The signs were produced by capturing data about the real motion of a human signer. In future, signs may be synthesised using a special sign language notation. A sign editor is being developed by UEA in order to enable deaf people and others to create high quality sign sequences for their websites without needing to be expert in sign language notation. These tools will provide graphical user interfaces for constructing individual signs, facilities for accessing signs from a lexicon, and composing signs into sequences. In future it would be possible to develop other applications of a similar nature where information to be presented follows a structure known in advance but where messages have a short lifetime and must be created quickly. Examples might be announcements at railway stations, or descriptions of job offers, where content creation tools usable by hearing people would follow the pattern of the weather forecast creator. ViSiCAST is supported by the European Union, as Information Society Technologies project IST-1999-10500. For further information go to: www.visicast.sys.uea.ac.uk or contact John Glauert, UEA Norwich, email: J.Glauert@uea.ac.uk Posted: 11 September, 2002
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