Abstract
One of the most-used rendering algorithms in Computer Graphics is the Ray-Tracing. The ''standard'' (Whited like) Ray-Tracing(1) is a good rendering algorithm but with a drawback: the time necessary to produce an image is too large (several hours of CPU time are necessary to make a good picture of a moderately sophisticated 3D scene) and the image is only ready to be observed at the end of processing. This kind of situation is difficult to accept in systems where interactivity is the first goal. ''Increasing Realism'' In Ray-Tracing tries to avoid the problem by supplying the user with a preview of the final image. This preview can be calculated in a considerably shorter time but permits that, with some margin of error, the user can imagine (even see, sometimes) some final effects. With more processing time the image quality continues improving without loss of previous results. The user can, at any time, interrupt the session if the image does not match what he wants. Simultaneously with the above idea, it is necessary to accelerate image production. Parallelism is then justified by the need of more processing power. The aim of this text is to describe the Interactive Ray-Tracing Algorithm implementation, using a parallel architecture based on Transputers. An overview of the architecture used is presented and the main parallel processes and related problems are discussed.

Abstract
People with autism spectrum disorder (ASD) find it difficult to recognize and respond to emotions conveyed by the face. Most existing methodologies to teach people with ASD to recognize expressions use still images, and do not take into account that facial expressions have movement. We propose a new approach that uses state of the art technology to solve the problem and to improve interactivity. It is based on an avatar-user interaction model with real time response, which builds upon the patient-therapist relationship: it is designed to be used by the therapist and the patient. The core technology behind it is based on a technique we have developed for real time facial synthesis of 3D characters.

Abstract
The importance of the spatial component of data items has been long recognized and gave rise to a successful line of research and development in Geographic Information Systems (GIS). In many application domains it is also essential to deal with the evolution of data along time and to integrate spatial, temporal and other aspects of the information domain in an expressive and operationally effective manner. Until recently, temporal solutions provided by spatial database systems were semi-temporal approaches lacking full temporal support. As a consequence, most spatial database systems manage snapshots of the present state of facts without fully exploiting historical temporal aspects. This paper provides preliminary results on a spatiotemporal database implementation. The proposed system builds on existing database technologies, TimeDB and Oracle Spatial, for temporal and spatial support, respectively. The justification for the choice of these technologies is given, based on the state of the art in spatial and temporal database research. The integration of the spatial and temporal components is achieved with the extension of the TimeDB implementation layer. A set of goals has been established in order to cover both the integration of the spatial support and the enforcement of the temporal requirements in the extended system. Issues and solutions are presented and illustrative examples show the use of the implemented functionalities.

Abstract
Spatiotemporal databases provide effective means to represent, manage and query information evolving over time. However, the visualization of record sets that result from spatiotemporal queries through traditional visualization techniques can be of difficult interpretation or may lack the ability to meaningfully display several instants at the same time. We propose a Temporal Focus + Context visualization model to overcome issues from such techniques resorting to concepts from Information Visualization. In this model, Focus + Context is applied to time rather than, as more typically, to attributes or space, and allows large amounts of data from distinct periods of time and from several record sets to be compressed onto one. Underlying the proposed visualization technique is the calculation of a temporal degree of interest (TDOI) for each record driven by specific analysis, exploration or presentation goals and based on the record valid time attribute, as well as on user-defined temporal visualization requirements. In the mapping stage of the visualization pipeline, the TDOI for a record is used to control graphical properties, such as transparency and color. More complex rendering properties, such as sketch drawing edges or other non-photorealistic enhancement techniques, can also be used to convey the temporal aspects of data, replacing the original graphical features of the record data. By enhancing or dimming the representation of a data item, according to the corresponding degree of interest, it is possible to meaningfully compress information about distinct temporal states of data onto the same visualization display. The model has been applied to several test scenarios and proved appropriate and useful for a wide range of domains that require the display, exploration and analysis of spatial information discretely evolving over time. Information Visualization (2008) 7, 265-274. doi: 10.1057/palgrave.ivs.9500188

Abstract
As new standards for technology specifications related to XML are unveiled, and stable tools to implement them become available, the widespread usage of XML as an universal format for data exchange between heterogeneous systems (using the Internet), will increasingly become a reality. Therefore, in order to deal efficiently with the large amounts of XML data that will be generated in the near future it is imperative to find efficient alternatives for the storage and management of this special kind of data. For that matter, object-oriented databases seem to be a good alternative. In this paper, we begin with an analysis of the different alternatives available to store and manage XML data. After that, we concentrate our attention on the Object-Oriented (OO) database approach and, in that context, we present a first set of rules that allow the translation from a simple database schema specified in ODL (Object Definition Language) into a schema specified in XML-SCHEMA. In the near future we intend not only to expand this set with new rules that will handle other, more complex, OO modeling constructs, but also to create another set Of transformation rules to work the other way round (i. e. from XML-SCHEMA to ODL). Our aim is to cover all the possible modeling situations one may come across in OO database schemas specified in ODL.

Abstract
The XML (eXtensible Mark-up Language), proposed by the W3C (World Wide Web Consortium) as the new standard for data representation and exchange in the Internet, is a document mark-up (meta) language that seems adequate to the needs of today's World Wide Web. With the proliferation of XML documents in the Web, it is necessary to store and query them efficiently. In this article, it is our purpose to investigate the different approaches currently available to the storage and management of XML data. Moreover, we intend to analyse the main characteristics of some of the XML query languages, which have been proposed both by the Database and Internet communities, namely XML-QL, XQL, Quilt, and Xquery. The latter has been proposed by the W3C Query Working Group with the purpose of providing a standard for a XML query language. We believe that a query language such as Xquery will certainly accelerate the utilization of XML as an alternative approach to data storage, since it will make possible to interrogate, efficiently and in unpredictable ways (queries ad hoc), XML documents.