Abstract
This paper presents the requirements and specifications of videotelephony services and applications that are being developed or adapted to take advantage and demonstrate the potential of the broadband access networks based on the adaptation of CATV networks for interactive services. Furthermore, it emphasises the experience, problems and conclusions that are being acquired by using the Digital Audio-Visual Council (DAVIC) framework to implement such type of services and applications.

Abstract

Abstract
The Department of Biology of the University of Tras-os-Montes e Alto Douro analyses every year a large number of chestnut-tree leaves, in order to measure their biometric characteristics, namely the leaf area, dimensions of the enclosing rectangle, number of teeth and secondary veins. Because for a human operator this is a time consuming and error prone task, a computer vision system has been set up to improve the process. The task of measuring the leaf presents no major problems, while counting the number of teeth and secondary veins has proved to be complex at the resolutions used. This paper describes the state of the project, going into some detail on the algorithms. A complete system has been assembled, based on an PC connected to an imaging system. A windows-based application has been developed, which integrates the control of the operations to grab, store and analyse images of different varieties of chestnut-tree leaves in an organised way. Because the accuracy of the computer vision algorithms used is not sufficient for the system to be completely autonomous, a semi-automatic solution has been adopted. The operator validates or corrects the results of the automatic analysis. This solution leads to a significant improvement in the performance of the human operator, both in terms of speed and quality of the results.

Abstract
Vehicle number plate recognition systems are expected to have numerous applications in traffic surveying and monitoring, e.g. finding stolen cars, controlling access to car parks and gathering traffic flow statistics. The Computer Vision Group at the University of Tras-os-Montes e Alto Douro, in collaboration with the Universities of Aveiro and Bristol, has been developing a number plate reading system [3][4][5]. The system builds on the experience gained by the Computer Vision Group at the University of Bristol while developing previous transputer based prototypes [5][6][8][12]. The main tasks of a number plate recognition system are the location of the number plate area in the image, the segmentation of the characters and their identification. These tasks are strongly inter-related, mainly because the way to check if the number plate has been correctly located is based on the result of the character identification process (it should correspond to a predefined syntax). Algorithmic improvements to previous versions of the system, based on the results of intensive testing, are described in the paper. For the location of the number plate area in the image, a new line-based method has been developed. The method, instead of looking for character like shapes in the image, takes advantage of the "signature" of the number plate area in a horizontal cross-section of the image. The method used for the segmentation of the characters is derived from a technique first proposed by Lu [8]. The identification of the characters uses the OCR engine developed by Barroso et al [3][4], based on the critical points method [10][11].

Abstract
Vehicle number plate recognition systems are expected to have numerous applications in traffic surveying and monitoring, e,g. finding stolen cars and controlling access to car parks. In this paper algorithmic improvements to a previous version of a number plate reading system are described. The work builds on the experience gained by the Computer Vision Group at the University of Bristol. This paper addresses the problem of locating the number plate area in the image and proposes a new line based method for number plate location, which is suitable for realtime number plate recognition.

Abstract
Ray-Tracing is a well known algorithm that simulates the reflection and refraction of light rays in the objects surfaces, beginning with rays sent from the view point. Each ray has to be tested against objects in the 3D scene and this is very time consuming. This paper describes one parallel solution. It is oriented to a general network, where each processor manages data and tasks and shares them with the others to optimise common resources utilisation. In this context, a Virtual Sharing Memory (VSM) is used and an efficient load balancing strategy can be implemented. With this approach, the amount of messages in the network tends to increase and strategies to reduce them are needed. Schemes to optimise remote accesses to data have been developed, namely a special type of multicast message addressing named InPathTo. © Springer-Verlag Berlin Heidelberg 1997.