Marcelo Dreux

An object model for collaborative CAD environments

This paper presents a distributed dynamic object model that is aligned with the concept of design history in the context of design problem solving activities. A distributed object model is proposed as an enabling feature for distributed CAD (computer-aided design) allowing teams to work cooperatively, accessing and exchanging information at run time in a distributed engineering environment. The architecture of the proposed CAD environment allows for the artefact properties to be associated with any relevant aspect of the design process, including those related with the artefact specification, but also with the organisation hierarchy, planning and process workflow.

Distributed object model for collaborative CAD environments based on design history

This paper presents new concepts for distributed dynamic design environments that deal with three aspects not effectively considered by the design literature in an integrated way: design history, CAD data model, and virtual prototyping. The present work details a design history model that gives support to views of higher levels than those usually found in design journals of CAD systems. The dynamic nature of the distributed environment is provided by an innovative mechanism that is not dependent on CORBAs DII or any other specialized middleware structure. Moreover, this paper presents an effective integration of a geometry bus on the top of a communication layer with strong support to mutant distributed objects at run time.

A heterogeneous system based on GPU and multi-core CPU for real-time fluid and rigid body simulation

Computational fluid dynamics in simulation has become an important field not only for physics and engineering areas but also for simulation, computer graphics, virtual reality and even video game development. Many efficient models have been developed over the years, but when many contact interactions must be processed, most models present difficulties or cannot achieve real-time results when executed. The advent of parallel computing has enabled the development of many strategies for accelerating the simulations. Our work proposes a new system which uses some successful algorithms already proposed, as well as a data structure organisation based on a heterogeneous architecture using CPUs and GPUs, in order to process the simulation of the interaction of fluids and rigid bodies. This successfully results in a two-way interaction between them and their surrounding objects. As far as we know, this is the first work that presents a computational collaborative environment which makes use of two different paradigms of hardware architecture for this specific kind of problem. Since our method achieves real-time results, it is suitable for virtual reality, simulation and video game fluid simulation problems.

Software shaders in interactive environments using relief impostors

This work presents an architecture for real-time visualization, which is able to render a set of 3D objects by using the CPU idle time. The objects being rendered are sent to the graphics pipeline as relief impostors. Their depth maps are used to apply 3D image-warping operations in order to prolong the life cycle of the synthesized images. While an image is within the graphics pipeline the CPU idle time is used to generate additional necessary images. With this method, it is possible to render images with special illumination models and effects that are impossible or unsuitable to be implemented with the shaders of the available graphics cards.

An architecture for the design entity

This paper proposes a new model for the representation of design processes based on the evolutionary aspect of this activity. Also this work presents an innovative approach to object-oriented design processes and a new pragmatic view of the Design Problem Space (DPS). Furthermore, the principles underlying the model are derived from a working CAD system in furnace design developed during the present research work. The information related to the artifact form (space representation), as well as those associated to the functions (rules and nature laws) that the form should attend to, are incorporated by the model. The proposed model is structured in terms of a small number of object types which are capable of building an efficient and robust hierarchical tree. This tree incorporates all the requirements associated with the artifact from the conceptual stage up to the stage of the artifact complete specification.

A shading model for image-based object rendering

In order to obtain models of complex virtual environments, there are many solutions that make use of image-based rendering techniques. When using a set of images to represent an element in space as a billboard, there are some problems related with the shading calculations, once these elements are just planes in space. This article presents a new approach for shading objects represented by images, which divides the problem into two parts: the shading maps generation for an object with specific set of lights in the environment and real-time shading simulation for a specific observer point of view and object location.

2D texture refinement using procedural functions

In computer graphics, aliasing is a problem which is always present when discrete elements are mapped to continuous functions or vice-versa. Although there is no general solution for this kind of problem, there are many techniques that aim at reducing the effects of aliasing. The article first discusses how interpolation methods are usually applied in order to correct this problem and shows the limitations of those techniques. It then presents another solution for this problem, that can be used together with the interpolation. It increases the texture details, making use of procedural functions.