Contributions to Virtual Reality
This thesis presents contributions to Virtual Reality organized in three topics: visual perception, immersive scenarios and ubiquitous visualization.
Visual perception in virtual reality devices differs from perception in the real world in several aspects. Stereoscopic displays can simulate the disparity of images perceived by each eye in the real world, to provide depth perception. However, this solution is limited. Correctly simulating the view from each eye of a virtual environment, so that eye convergence to virtual objects is similar to converge to equivalent real objects, requires precise knowledge of the viewing conditions of the display. Furthermore, stereo displays do not simulate the light field behavior that triggers accommodation (i.e. focus) of the eye, whereas in reality accommodation varies as we look at objects at different distances. Conventional head-mounted displays feature a pair of displays at fixed positions and thus require a fixed eye accommodation for them to be seen sharply. This thesis proposes ways to tackle these problems using variable-focus HMDs and special calibration methods. A calibration algorithm is proposed to estimate stereo projection parameters for each specific device, and calibration and control procedures are proposed to obtain expected accommodation stimuli at different virtual distances.
This thesis also proposes solutions to practical problems in immersive scenarios. The thesis addresses problems in diverse scenarios: construction machinery simulators, weather radar volumetric visualization and manual arc welding simulation. They demand varying degrees of immersion and special, innovative visualization solutions are proposed to fulfil their requirements.
Finally, contributions are presented for ubiquitous visualization scenarios where users access interactive 3D applications remotely. Here, running on networked devices using conventional web browsers is the main requirement, to the detriment of realism and immersion. The thesis follows the evolution of Web3D standards and technologies to propose original visualization solutions for volume rendering of weather radar data, e-learning on energy efficiency, virtual e-commerce and visual product configurators.