Galactica, a Digital Planetarium for Immersive Virtual Reality Settings

Galactica, a Digital Planetarium for Immersive Virtual Reality Settings

Miguel Sales Dias (Microsoft Language Development Center, Lisboa, Portugal and ISCTE Instituto Universitário de Lisboa, ISTAR-IUL, Lisboa, Portugal), Jorge d'Alpuim (ISCTE Instituto Universitário de Lisboa, ISTAR-IUL, Lisboa, Portugal) and Pedro Caetano (IST - Técnico, Universidade de Lisboa, Lisboa, Portugal and ISCTE Instituto Universitário de Lisboa, ISTAR-IUL, Lisboa, Portugal)
DOI: 10.4018/IJCICG.2016010102
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The authors describe a new Digital Planetarium system and application (“Galactica”), for interactive visualization of astrophysical data and phenomena in immersive virtual reality (VR) settings, based in OpenSceneGraph (OSG). Galactica enables a visual and aural experience of a virtual space traveler, that can go anywhere in the Solar System and the Milky Way at any speed. The application was tested with an available dataset of such scenery, featuring 100 629 textured billboards representing stars and additional 104 328 polygons, representing constellations, orbits, planets and respective moons of the Solar System. The authors have computed the frame rate, GPU traverse time, Cull traverse time and Draw traverse time for three visualization conditions: (A) standard OSG view frustum culling technique; (B) view frustum culling with an octree organization of the scene; (C) view frustum culling with same organization of the scene and the occlusion culling algorithm. They have generally concluded that their acceleration techniques out-performs the standard OSG view frustum culling for the mentioned metrics, when around half or less than half of the dataset is in view of the virtual camera.
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Since the primordial times the human kind has an enormous fascination by all the phenomena observed from the sky standing above us. The construction of planetariums since the ancient Egypt and Classical Greece times, shows the desire of astronomers and astrophysicists to convey to the general public the instruments and knowledge regarding the astronomical and astrophysical fields. The planetariums have suffered a lot of improvements along with the several generations since they were just some mechanical models representing the planets orbits, to the digital planetariums of today, with the most advanced cluster of high-end graphics computers allowing interactive exploration of the known Universe, such as the Hayden Planetarium (Hayden 2015) at the American Museum of Natural History, New York, that runs the UniView system (Klashed 2010). Influenced by this example, we hypothesized the viability of the development of a Digital Planetarium, able to visualize and interact with publicly available datasets, correctly representing sensed astrophysical phenomena, and able to run in a wide range of Virtual Reality (VR) systems, from non-immersive desktop/tablet to fully immersive systems such as a CAVE (Cruz-Neira 1992). In fact, given the access of our tem to a similar immersive VR infrastructure in southern Portugal (near the city of Grândola), referred to as the CAVE Hollowspace of Lousal (CaveH) (Soares, 2010), our endeavor included putting in place in our VR system, visualization acceleration techniques in order to provide the user with real-time interactive experiences, within an environment capable of depicting photorealistic scenes in stereoscopy, in a high resolution multi-display projection system. Additionally, we postulated the creation of an interactive user experience allowing realistic and immersive virtual journeys across the known universe, independently of the dimension of the astrophysical dataset, via the adoption of suitable optimization techniques for data visualization, data storage and management and data navigation at astronomic scales. Finally, we sought of defining thematic astronautic space travels, via a storyboard, depicting rich multimedia information about the astrophysical phenomena observed along the correspondent voyage, within the VR environment.

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