Czech integrator AV Media has used eight Optoma projectors for a huge hemispherical dome rear-projection at the National Technical Museum of Prague.
The Measurement of Time is one of 12 permanent exhibitions open to the public in the museum. It contains elementary time-measuring devices including sundials, waterclocks, fireclocks, hourglasses and mechanical clocks, as well as electric and electronic devices and clocks based on quantum principles. The exhibition showcases the different approaches to measuring time across cultures and through history.
The museum commissioned integrator AV Media to create an impressive hemispherical dome centrepiece for the exhibition. This was to show an evocative film on the phenomenon of time, and would be one of the key attractions for the museum’s reopening event.
The installation had to create an atmospheric and emotive space with perfectly blended imagery within a huge hemispherical dome - 4.6m wide and 3.8m high. The project had an additional challenge in that the imagery had to be back-projected, because of a large column at the centre of the dome.
Jan Buriánek, 3D specialist from AV Media, commented: "We really appreciated the flexibility of the projectors, especially the short-throw lenses and lens-shift capabilities. This installation was particularly unusual in that the imagery had to be back projected. Optoma’s EX785 was the only projector that met our parameters both in terms of functionality required and budget."
Eight Optoma EX785 projectors with short-throw lenses were installed to back-project around the hemispherical dome. Each projector was fed by a media player with synchronised video and audio, then warped and blended to form one seamless image around the whole hemispherical dome. The full lens shift and interchangeable lenses made installation straightforward. The short-throw lens used in the projectors has a throw ratio of 0.8:1 and is highly suited to rear-projection installations.
The audio used a directional sound system with the sound focussed upon a specific area within the dome. An external 5.1 system was installed for just sound atmosphere within the dome. This was then complemented by the powerful 10W built-in speakers to create directional sounds from each of the eight projectors.
Construction and installation took four weeks to complete, with the dome constructed from wood and metal. The main contractor was Mplus, with the architectural solution by SGL Architects. AV Media designed the technical AV elements of the project, installing, warping and blending all projectors within one week.
"We had not initially intended to use both the external sound system and the [projectors '] built-in speakers but it works so well to create atmospheric and directional sound. We are delighted with the results of this very special installation for both its visual impact and impressive sound," explained Buriánek.
This huge dome creates an immersive space for the abstract shows themed around the subject of time. Three different audiovisual presentations are projected currently, with more shows planned by the museum for the future. The 5,000 ANSI lumen projectors fill the whole dome with clear bright imagery, and the experience is completely immersive as the projectors are out of sight to visitors.