Overview of Tilted Planetarium

Overview of Tilted Planetarium (Dome Theater)

In China, many science and technology museums have built a sky hall. The diameter of the sky hall is generally about 10 meters, and the traditional horizontal (ground level) dome structure is mostly used. The traditional celestial hall demonstration is to combine the mechanical motion and optical projection of the demonstration equipment to reproduce the motion of the planet. The demonstration equipment is mainly a planetarium. The basic principle of the planetarium is to use a star projector to project the starry sky onto a hemispherical dome screen to form an artificial starry sky, and then project the sun, moon, and planets to the artificial starry sky through a sun and moon planetary projector equipped with a precision gear rotation system In the simulation exercise. When making astronomical demonstrations, the audience needs to look up and watch the astronomical landscape where the celestial bodies rise and fall and the stars move from star to star.

What we now call the tilted planetarium is similar to the design style of the China Science and Technology Museum Dome Screen Theater. It is fundamentally different from the traditional planetarium.

First, the architectural design of the dome is different. Its dome screen is tilted, with a tilt angle of 22º, and the audience is watching the film straight ahead.

For small and medium-sized astronomical halls, the inner diameter of the dome designed by us is 8-14 meters. According to different star theater design standards, the maximum number of seats that can accommodate the audience is about 120.

The dome theater can be built in the ordinary exhibition hall, or it can be built separately. If it is a separate structure outdoors, its unique sphere shape will often become the most iconic highlight of a building.

The architectural appearance of the dome screen theater can be divided into two types: line type and assembled type. The main body is a double-layer steel frame structure, and the inner and outer metal plates are connected with the steel frame. The outer curtain uses a support structure of more than 24 points, and the inner curtain uses a 16-point support structure to ensure the stability and firmness of the overall steel structure.

The outer curtain metal plate is connected to the steel frame with rivets, and has a different appearance of line type and pineapple type. The inner screen is a projection screen, which is composed of perforated aluminum plates. In order to reduce the influence of interference light on the screen picture, the reflectivity of the surface coating of the perforated aluminum plates is not more than 65%. The diameter of the perforation of the aluminum plate is not more than 1.5 mm, and sound-absorbing materials are spread behind the scenes to ensure good reverberation conditions in the spherical theater.

In the previous period, the development of China's dome screen projection equipment has been at a relatively slow stage. What we call the small and medium-sized dome theater (inclined celestial hall) lacks funds to introduce foreign 70mm dome screen movie equipment and films. For example, if a 35mm film system is used, the embarrassing scene of heavy projection equipment and no film is encountered. However, even in the case where the dome screen projection equipment and programs are relatively lagging behind, there are still units in China that try to adopt the design of the new tilting planetarium, using projectors instead of projectors, and digital images instead of film films. In recent years, Beijing, Anhui and Fujian have all built new tilting sky halls.

With the development and production of domestic fisheye projection lenses and the continuous introduction of digital astronomy science and education films, the tilted astronomical hall, the dome (ball) screen theater, will gain a larger space for development.

With the development of science and technology, the use of high-tech means of digital film production and computer storage and playback can create many astronomical landscapes that cannot be seen in traditional astronomical halls.

Today, digital technology is gradually replacing analog technology. For small and medium-sized planetariums, projectors can be used instead of movie projectors. In terms of technical solutions, it is feasible to adopt a single projector and multiple projectors. However, from the point of view of equipment investment and program resources, equipment investment of a single projector is much less, and there are many sources of screening programs. It is convenient for the live shooting and digital animation production of single astronomical programs, and playback.

The fish-eye projection lens is a key link in the celestial program broadcasting system using a single projector.

The fisheye projection lens needs to have a very wide angle of view, and the horizontal angle of view is usually required to be above 120º. The average projector lens is far from reaching the dome screen movie projection effect. This requires our projector to match the corresponding fisheye lens. It enables high-brightness projectors to project the image onto a hemispherical dome screen. In this way, it is possible to introduce dome-screen projection for small and medium-sized tilted planetariums.

For the majority of viewers, what interests them most is mainly the program content of the film, so there should be a large number of diverse film programs to support the presentation of the Planetarium.

Now, in astronomical demonstrations, you can introduce film and television expression methods, and use high-tech means of live-action shooting and digital film production and computer storage and playback. From the information capacity of the presentation content, from the expression means popularized by science, from the diversification and interestingness of the film content, there has been a big leap forward than before.

The produced astronomical program is stored in the computer, output directly to the projector through the data connection, and projected onto the dome screen. In this way, the problem of projector room construction and projection noise is fundamentally solved. Solve the problem of film quality degradation and film scrapping caused by the wear of film projections. Film programs can be shown all the time, and the picture quality has always been in a new state. The entire screening operation is also extremely simple.

Using digital animation technology to make the film, we can make many visual effects that traditional celestial hall cannot. For example, in the film "Vast Starry Sky", we can see the scene of a big collision of the stars, and in the film "Tornado", we can intuitively see the formation process of the tornado.

The planetarium uses a tilted dome, which allows the planetarium to show astronomical films as well as films from other disciplines, such as meteorological, geographic, and biological films. It can not only show films made by computer digital animation, but also show movies shot in real scene, such as the magnificent scene of spacecraft being launched, and so on. This is the advantage of taking a stand-alone solution.

With the astronomical science film, the dome theater became a dome screen hall.

With the meteorological science film, the dome theater hall became the dome screen astronomy and meteorological office.

With 4D motion pictures, the dome theater has become a 4D astronomical and meteorological hall, adding joy to popular science activities.

In this way, the astronomical hall that shows a single astronomical program has become a multi-functional demonstration hall.