Watching the Stars: Technologies of St. Petersburg’s New Planetarium
A new planetarium with the world’s biggest dome (37 meters in diameter) has opened in St. Petersburg; a unified system of 39 projectors allows for fulldome 360 videos. The new equipment was first tested at ITMO’s Higher School of Lighting Design. ITMO.NEWS visited the new planetarium and found out how these new projections work, and learned what issues such equipment presents.
The new Planetarium #1 is now the world’s biggest, having topped the record of its counterpart in Nagoya, Japan, with a diameter of 35 meters. The new dome was fixed into a historic building of a former gas-holder that once supplied St. Petersburg’s public lighting. The construction is similar to a saucepan in its appearance: round, with a hemispheric roof, and is located in St. Petersburg’s “grey belt”.
At the opening Sergei Poltavchenko, St. Petersburg’s governor, noted that such projects bring new life to the half-abandoned industrial buildings that separate St. Petersburg’s center from its new districts. Andrei Borisenko, astronaut and Hero of the Russian Federation added that, in a city where skies are so often overcast, the planetarium is a great opportunity for citizens to see the stars. Also, seeing the stars in a big city is hard due to light pollution.
According to the project’s initiator, entrepreneur Evgeniy Gudov, Planetarium #1 is one of the world’s most technologically advanced planetariums. At its heart is a sphere that houses 39 powerful projectors capable of projecting images with a resolution of 8K by 8K onto the dome. A resolution this high can be attained by filming a video with several 4K cameras or lots of HD cameras. It is most important for the cameras to be adjusted in a similar manner, each filming a part of the final image without overlapping. Then, special programs help combine the different videos into one with a really high resolution.
Modern planetariums use projectors of different capacities, and their light output is measured in lumens. The more lumen there are, the less projectors are needed to light the dome. Planetarium #1 makes use of 39 projectors connected into a unified system; each projector is responsible for a part of the image, and these parts are then blended into one.
“When you use several projectors to create one big image, apart from blending, there’s the problem of having different brightness in adjacent areas. For the image to look wholesome, you need to disguise it; in essence, you have to make the brightness even throughout the whole image. There are programs that solve this issue automatically by analyzing the distortions of test patterns projected on the surface. We’ve considered such solutions, yet decided to do everything manually. Also, we had to work on the problem of synchronizing the projectors,” explains Ildar Yakubov, Planetarium #1’s chief video engineer.
The planetarium’s equipment and content were tested at ITMO University’s Higher School of Lighting Design, using a mobile planetarium 10 meters in diameter. Usually, they use it for performances in collaboration with the Hungarian laser theatre Lux Aeterna at events like Geek Picnic. According to Nikolai Matveev, assistant professor at the School, the mobile set-up was used to test eight of the projectors and adjust the blending process.
“The software used to create fulldome projections is a lot more complex that what is used for 2D graphics. It makes use of 3D mapping technologies, which is the projection of an environment on a physical object with regard to its geometry – the planetarium’s dome, in our case. In essence, videos shown at the planetarium have the appearance of 360-degree videos,” comments Nikolai Matveev.
He adds that planetariums usually employ special dome casings to amplify the image’s sharpness. For instance, such casing has to be grey-ish, and not completely white. Also, hemispheric structures often demonstrate remarkable acoustics; thus, being at one side of the dome, one can easily hear what happens at the other. Thanks to that, planetariums are great for audio-visual performances.
“In future, specialists from the Higher School of Lighting Design would be eager to work with the new planetarium’s capabilities, as it is a vast space where one can experiment with light installations,” adds Nikolai Matveev.