Joaquim Madeira

Learn More
Polygonal meshes are used in many areas to model different objects and structures. Depending on their applications, they sometimes have to be processed to, for instance, reduce their complexity (simplification). This mesh processing introduces error, whose evaluation is important when choosing the kind of processing that is to be done for a particular(More)
Virtual Reality (VR) has been constantly evolving since its early days, and is now a fundamental technology in different application areas. User evaluation is a crucial step in the design and development of VR systems that do respond to users’ needs, as well as for identifying applications that indeed gain from the use of such technology. Yet, there is not(More)
Feature modeling systems usually employ a boundary representation (b-rep) to store the shape information on a product. It has, however, been shown that a b-rep has a number of shortcomings, and that a cellular representation can be a valuable alternative. A cellular model stores additional shape information on features, including the feature faces that are(More)
The complexity of a polygonal mesh is usually reduced by applying a simplification method, resulting in a similar mesh having less vertices and faces. Although several such methods have been developed, only a few observer studies are reported comparing the perceived quality of the simplified meshes, and it is not yet clear how the choice of a given method,(More)
The appropriate use of color in Visualization is a very important subject. The choice of the proper color scale to use with a particular data set is not just a matter of choosing the prettiest representation. Throughout the years researchers have studied this subject and managed to propose guidelines which help users along the process of color scale(More)
Meshes are currently used to model objects, namely human organs and other structures. However, if they have a large number of triangles, their rendering times may not be adequate to allow interactive visualization, a mostly desirable feature in some diagnosis (or, more generally, decision) scenarios, where the choice of adequate views is important. In this(More)