The Techopedia website describes stereoscopic imaging as “… a technique used for creating or enhancing the illusion that an image has depth by showing two slightly offset images separately to each eye of the viewer.”

Stereoscopic 3D (or stereo 3D) as a display technology isn’t new – in fact the first 3D film screened to an audience took place in a Los Angeles cinema in 1922.

3D in a dome, however, is a relatively new technology and experience. In 2008, the world’s first fulldome 3D stereo planetarium opened its doors in Hawaii. Now, there are several 3D domes globally – some operating as 3D fulldome, others as 2D fulldome with a 3D ‘insert’ window.

Great stereoscopy in a dome is a particular science in itself, as there are many challenges associated with the curved, immersive form of the screen and the range of audience seating locations within it – unlike standard single-projector cinemas, domes and other immersive displays use multiple projectors to create a single image, all of which have to be synchronised. Other factors that need to be considered and addressed include issues arising due to the cross-bounce of light caused by hemispherical projection, and how the wearing of 3D glasses and consequent field-of-view reduction could actually limit the immersive ‘effect’ of sitting under a dome screen.

In this blog, we discuss what stereoscopic 3D is, what it’s good for, and when it should be adopted.

What’s the difference between the commonly available 3D stereo display technologies?

Currently, active and passive stereo are the two main types of 3D display technology in use by planetariums, digital theatres and cinemas.

Active stereoscopy involves 3D glasses with built-in electronic components. On each side of the glass lens there is a liquid crystal layer, which seems invisible when not in use, but makes the lens dark when switched on. Once a timed signal is received from the emitter, both sides of the glass ‘flicker’ in a coordinated sequence that receives and synchronises images fed from the display to the left and right eye, creating the 3D effect.

Passive 3D is typically used by 3D cinemas as glasses are cheap, often disposable, and therefore better suited for larger audiences and higher footfall and audience turnaround. Left and right images are projected on screen with polarising filters used in front of the projector lens. To preserve the polarisation, a silver screen is used.

INFITEC (or Dolby 3D) is also a passive 3D technology, but is a patented process that uses optical filters with separate wavelengths compared to that of standard, polarised passive 3D. This has also been regularly used in dome and immersive environments.

How can 3D enhance an experience – whether entertainment, informal learning or research/science/data visualisation?

The dome gives the audience an understanding, in an interactive visual sense, of complex science or situations. It takes them inside the data. Imagine looking at an architectural model inside a 3D environment – you can visualise the data from any side, in plan view. 3D perspective adds detail and a level of comprehension that simply isn’t possible from seeing things in a standard 2D, recto-linear way.

How can a 3D visual experience be enhanced?

A 3D experience with added ‘physical’ effects such as fog, wind, motion or bass-rumbler seats, scent (and sometimes even water spray!) are referred to as a 4D experience. Sometimes humorously more! These, when integrated in a complementary way, can increase the perceived ‘reality’ of the experience.

What we do see is that audio is most certainly the best added ‘effect’ – great audio in an immersive space is not secondary, but equal to the visual experience. A first-class audio experience must be carefully and well designed. Either locally embedded audio, or filling the whole digital canvas, audio can truly enhance the sense of scale within the environment.

What are the limitations of 3D in the dome?

3D isn’t always the right choice, and whether or not 3D should be adopted as part of a system can be determined after careful consideration of the application and requirement.

In the case of looking at large-scale datasets, our opinion is that stereoscopic 3D is not the right answer.

If you plan to be looking at particular data points where the presenter and audience need to drill into detail, to microscopic level as an example, then stereoscopic 3D as a tool can be very powerful and with real value.

Our consulting and design teams assess each of these considerations and offer the right technology choices for the application.

How are glasses managed?

Hygiene factors in public environments are critical, especially with new sanitising and virus control regulations. We work with a range of technologies to ensure the processing and rapid turnaround of glasses is managed well.

Factoring in the frequency of shows, audience turnarounds, and the available number of glasses, we ensure timely process management for high volume usage and can propose the right approach.

Can existing content and media be converted from 2D to 3D? What’s the global library of 3D fulldome content like?

The global library of ready-to-go 3D immersive content is extremely specialised and typically quite limited. However, we work with specialist data visualisation and can create custom 3D versions of that data. We also have close partnerships with content houses that can produce custom 3D shows.

Objects, data and media that don’t have natural depth-of-field, or can’t show particular coordinates, are better staying in 2D – using the ‘immersiveness’ of the dome to create a 3D-like effect for exploring the content.

3D systems are capable of playing both 2D and 3D content. A 2D experience can often be just as powerful in an immersive space. Sometimes a 3D system may run in 2D-mode, shifting into 3D-mode at key moments. Specialist display systems are capable of running in both 3D and 2D modes simultaneously, allowing us to insert 3D into areas that need it. This is referred to as the ‘green screen effect’ or stereo insertion.

Can any real-time data visualisation be converted into 3D?

It has to be fit for the job, but our media teams can run most data through a specialist render engine and convert into 3D assets and 3D models for the dome or immersive space.

Is 3D suitable for all ages?

Generally, children under age of 6 dont have the fully developed cognitive processing power to necessarily see depth-of-field in the same way as older children and adults do.

It’s also important to note that it is estimated between 2% and 12% of people are stereo-blind which is the term given to viewers who are either unable to see the 3D effect, or suffer unacceptable side-effects such as headaches and nausea. Reasons for stereo-blindness include loss of vision in one eye, and medical disorders that prevent the eyes focussing and/or aligning correctly.

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