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Performance improvements in graphics hardware have made it possible to visualize complex virtual environments and provided opportunities to interact with these in a more realistic way. In this paper two different types of Virtual Reality applications for simulating a billiards game are presented. In one application a commercial haptic interface is used to provide a force feedback, thus rendering the interaction realistic and exciting to the user. However, there are limitations due to the use of a commercial haptic device which has not been specifically designed for this game and thus limits the workspace. Also, in the commercial device, it is not possible to use the left hand when aiming and striking the ball, as you can in a real game of billiards. In order to overcome these limitations another type of simulation has been developed using a real billiard cue; its movements are reproduced in the virtual environment using a visual marker detection system. No force feedback is provided to the player. In the game simulations the virtual environments have been built using the development environment XVR in the first simulator and OpenSceneGraph in the second; rigid body dynamics have been simulated utilizing the ODE and PhysX physics engines. ARToolkit was the visual marker-based detection system utilized to replicate the movements of the real cue used by the player in the virtual environment of the second simulator. [ABSTRACT FROM AUTHOR]

The aim of this work is to develop a realistic virtual model of the human brain that could be used in a neurosurgical simulation for both educational and preoperative planning purposes. The goal of such a system would be to enhance the practice of surgery students, avoiding the use of animals, cadavers and plastic phantoms. A surgeon, before carrying out the real procedure, will, with this system, be able to rehearse by using a surgical simulator based on detailed virtual reality models of the human brain, reconstructed with real patient's medical images. In order to obtain a realistic and useful simulation we focused our research on the physical modelling of the brain as a deformable body and on the interactions with surgical instruments. The developed prototype is based on the mass-spring-damper model and, in order to obtain deformations similar to the real ones, a three tiered structure has been built. In this way, we have obtained local and realistic deformations using an ad-hoc point distribution in the volume where the contact between the brain surface and a surgical instrument takes place. [ABSTRACT FROM AUTHOR]