Maria Andréia Formico Rodrigues

Chaos and Graphics: An interactive simulation system for training and treatment planning in orthodontics

We have designed and implemented an interactive simulation system for training and treatment planning in orthodontics. Currently, both treatment planning, and the choice of a proper appliance model, are based exclusively on clinician expertise. Most orthodontists work by trial and error when estimating the loading conditions that will achieve the desired tooth movement. There is a strong need for computer methods that will enable them to make realistic visual predictions of the final positions of the teeth and the changes in shape that the dental arch undergoes. To validate our simulator, we used cephalometric measurements and dental cast data taken during one-year follow-up orthodontic treatments. The results demonstrated a closely degree of fit between experimental orthodontic treatments and simulated case studies. In addition to its use in therapy planning, we expect our simulator to be a useful environment for training, providing a means to explore the temporal evolution of planned treatments.

Interactive Mobile 3D Graphics for on-the-go visualization and walkthroughs

Developing interactive 3D graphics for mobile Java applications is now a reality. Recently, the Mobile 3D Graphics (M3G) API (also known as JSR-184) was proposed to provide an efficient 3D graphics environment suitable for the J2ME platform. However, new services and applications using interactive 3D graphics, which have already achieved reasonable standards on the desktop, do not exist for resource-constrained handheld devices yet. In this work, a generic architecture for visualizing and navigating through 3D worlds in a mobile setting was designed and implemented. In particular, a 3D virtual tour application was developed based on the proposed architecture, where multiple mobile clients using M3G navigate through and interact with each other in a shared 3D space.

Collaborative virtual training using force feedback devices

Force feedback plays an important role in collaborative virtual reality environments, mainly for programmers of haptic visualization tools. Whereas a great deal of work has gone into graphical displays over the past years, little has changed on the input side. One of the problems that has slowed down development in this area is the difficulty of integrating the visualization of a scene, the interaction of the user with the scene, the feeling for the user to be immersed inside the scene, and finally, the input devices. We describe the architecture we have designed, implemented and tested for a collaborative virtual training using force feedback devices. In particular, it provides device independence and easy extensibility through a compartmentalized and multilayered model. We also present examples of how force feedback joysticks can be integrated into training exercises using our prototype.

A LOOSELY COUPLED ASPECT LANGUAGE FOR SOA APPLICATIONS

The aspect-oriented programming (AOP) paradigm offers software developers with powerful modularization abstractions to help them explicitly separate design concerns at the source code level. However, the impact of AOP in the service-oriented architecture (SOA) paradigm has been dwarfed by the fact that existing AOP solutions are tightly coupled to a particular programming language, middleware system or execution platform. Clearly, this not only restricts the implementation choices available to application developers, but it also clashes with the heterogeneous and loosely coupled nature of SOA. This paper presents the Web Service Aspect Language (WSAL) that seamlessly integrates AOP and SOA concepts, thus avoiding the drawbacks of existing solutions. In WSAL, aspects themselves are freely specified, implemented and executed as loosely coupled web services. This characteristic allows WSAL aspects to be easily woven into the message flow exchanged between service consumers and service providers, in a way that is completely independent from any particular implementation technology. This paper also reports on the implementation and preliminary evaluation of a prototype aspect weaver for WSAL, which is based on an existing web intermediary technology.

Supporting guided navigation in mobile virtual environments

Developing interactive 3D graphics for mobile Java applications is a reality. Recently, the Mobile 3D Graphics (M3G) API was proposed to provide an efficient 3D graphics environment suitable for the J2ME platform. However, new services and applications using interactive 3D graphics, which have already achieved reasonable standards on the desktop, do not yet exist for resource-constrained handheld devices. In this work, we developed a framework for supporting guided navigation in mobile virtual environments. To illustrate its main functionalities, a virtual rescue training was designed, implemented and tested on mobile phones. Users can load virtual environments from a remote PC server, navigate through them, find an optimal and collision-free path from one place to another, and obtain additional information on the objects.

Experiences with rapid mobile game development using unity engine

In this work, we describe our experiences with FunCopter, a casual game we have designed and implemented using Unity engine, suitable for portable devices. We emphasize some general principles, particularly with respect to rapid game development and constrained graphics. In addition to that, we present the main activities realized in each software engineering phase and the lessons we learned during its development. These descriptions include details from the initial concept to the fully realized, playable game. This work will share general but important experiences with Unity, particularly interesting for game developers in beginners level.

A lightweight 3D visualization and navigation system on handheld devices

This work presents a lightweight 3D visualization and navigation system we have proposed and implemented on handheld devices, using the Open Graphics Library for Embedded Systems (OpenGL ES API). The visibility algorithms view-frustum culling, backface culling (this one available in the OpenGL ES API), and a combination of view-frustum culling and backface culling, associated to different depth levels of Octrees (used to partition the 3D scene) were implemented and used to optimize the processing time required to render 3D graphics. The system was then tested using these combinations of algorithms and performance analyses were conducted for situations where the camera walks through an environment containing 6199 polygons. The results show that navigation at interactive rates of 10.07 and 30.61 frames per second can be obtained using the Pock-etPC iPaq hx2490b and the mobile phone Nokia n82, respectively.

An evaluation of a collision handling system using sphere-trees for plausible rigid body animation

Collision handling plays a fundamental role for achieving realism and interactivity in 3D graphical systems. Nevertheless, it is still one of the bottlenecks of such systems. In this work, we use the Sweep & Prune algorithm and Sphere-Tree approximations of the objects to perform the collision detection. Besides, we show how to compute the contact data for the narrow phase out of the overlapping leaf spheres from the Sphere-Trees. For collision response, we have implemented a simple, yet efficient and accurate, impulse-based method. A number of experiments in virtual scenarios with objects falling in a static plane were conducted. The results show that when Sphere-Trees with 2 levels are used for scenarios with a great number of objects (up to 200 falling objects) and simultaneous contacts among them (up to 16381.50 contacts at each frame on average), our system is capable of generating real time plausible rigid body animation, with always more than 30 frames per second (FPS) on average.

Performance Evaluation of a Hybrid Algorithm for Collision Detection in Crowded Interactive Environments

Crowded interactive environments composed of a large number of objects need a fast, accurate and scalable mechanism for collision detection. This work presents a detailed performance analysis of a hybrid collision detection algorithm for highly interactive and crowded environments. Extensive tests were conducted and the performance of the algorithm was evaluated in terms of output quality and running time, by applying a usability criteria. The results show that interactive frame rates for environments composed of 1000 colliding objects can be successfully achieved with a good level of user satisfaction using the sweep & prune algorithm together with sphere-trees generated by the combined algorithm

A serious game to improve posture and spinal health while having fun

We present a serious game which we believe that has the potential to improve posture and spinal health while still having fun. In our game, we correct postural deviations and perform and memorize lengthening sequences. It operates in the single and multiplayer modes using haptic devices for game control and uses the Microsoft Kinect for gestural interaction. We also conducted user studies to evaluate our game. The results show that observations and experiences of posture correction and lengthening influence the behavior of the users, stimulating reflections and initiatives in their real lives during game play.