Computer Graphics has been accepted as a solid scientific topic all over the
world. In Portugal, we have also been assisting to its maturity, with the
creation of interesting research groups that maintain a regular work in the area
and in closely related areas, such as multimedia, virtual and augmented
environments, user-friendly and interactive multimodal interfaces.
Technology transference is being ensured as can be proved by the increasing
number of enterprises that are already working in the country and using
associated technologies for video production, 3D animation, computer games and
multimedia products, among others.
This special issue of VIRTUAL Journal, titled Advances in Computer Graphics in
Portugal, intends to review the recent advances made in those areas by research
teams working in the country. Therefore, this special edition gives an
opportunity to all players to present the best they have produced in the recent
past.
To achieve that goal, a special call for papers was launched in September 2005.
In addition, some authors were invited to extend earlier versions of papers
already presented in the most recent Portuguese conferences on Computer
Graphics. The resulting submissions, ultimately written in English, were then
peer reviewed by the Journal advisory board and consequently published.
Based on their participation in the conference Interacção 2004, held in FCUL (Faculdade
de Ciências da Universidade de Lisboa) from 12th-14th July 2004, J.M. Dias et
al. present a tool called ARTIC, which is a tangible interface that offers a 3D
user interaction allowing six degrees of freedom. It can be used in augmented
and mixed reality environments.
Games 2004 was held in FCUL as well, from 12th-13th July 2004. In this workshop,
J. Pereira et al. presented the development of an agent-based architecture for
MMORPG (Massively Multiplayer Online Role Playing Games). The corresponding
paper describes work aimed in the development of an Artificial Intelligence
layer for including agent-based participants in a game framework.
Five other papers were selected from the 13th Portuguese Symposium on Computer
Graphics that took place at UTAD (Universidade de Trás-os-Montes e Alto Douro,
Vila Real), from 12th-14th October 2005. They are mentioned here in the same
order they appear in the proceedings.
S. Silva, J. Madeira and B. Santos sign the first of these papers, where a tool
for analysing and comparing polygonal mesh features is presented. This tool
allows visualizing and comparing the values obtained for different figures of
merit. For instance, it is possible to use different kinds of graphical
representations in order to visualize intrinsic properties of a mesh or the
distribution of deviation values of a processed mesh regarding its original.
The second paper deals with the generation of Coons surfaces and their
representation as B-Spline and NURBS forms. E. Oliveira and J.C. Teixeira refer
methods providing adjustment of the weights of the control points in the
rational form and compare the resulting surfaces based on a statistical test.
The authors also present a methodology to easily analyse and compare the
generated surfaces.
Another paper presents a new technique for regular mesh subdivision used to
achieve a final smooth surface from a small control mesh that is poorly refined.
In the extended version, F. Birra e M.P. Santos show how the algorithm runs
entirely on the GPU and illustrate the presentation with some examples taken
from cloth simulations, where the level of detail varies dynamically and the CPU
power can be directed towards the more demanding physical simulation.
A paper describing the design and construction of a blowing-sensitive tangible
interface, referred to as Blowpipe, is presented by J.M. Dias and A. Pocinho.
This system has been tested in augmented and mixed reality entertainment
environments and was put into effect in a game in which virtual darts are shot
at a target.
The fifth selected paper from the 13th Portuguese Symposium on Computer Graphics
was written by D. Gonçalves and J. Jorge. It focuses on the difficult task that
a common user experiments in searching for specific documents in a computer,
including non-textual documents. The authors state that narrative-based
interfaces can be a natural and effective alternative to facilitate document
retrieval. Therefore, these new retrieval mechanisms will reflect the way users
naturally remember and refer to their documents. An implemented prototype is
also referred in the paper, together with the evaluation of the accuracy of the
information contained in story samples.
A paper not previously presented in any of the scientific events referred before
is also published in this special issue of the VIRTUAL Journal. Written by H. du
Buf et al., it presents a way to create pictures having the perception models
(human vision) in mind rather than a computer vision. The paper claims that
automatic rendering can be achieved by applying four image representations in
the visual system: colour constancy, coarse background brightness, multi-scale
line and edge representation and multi-scale keypoint representation.
Finally, we would like to express our gratitude to the Advisory Board colleagues
for their valuable work in reviewing all the papers and to the Editorial
Production staff for their efforts in making this material available, as well as
to all the authors for their valuable contributions in this work.
Lisbon, July 2006
Manuel Próspero dos Santos
A. Augusto de Sousa
Adriano Lopes