360-degree videos, also known as immersive videos or spherical videos, are video recordings where a view in every direction is recorded at the same time, shot using an omnidirectional camera or a collection of cameras. During playback the viewer has control of the viewing direction like a panorama.
360-degree video is typically recorded using either a special rig of multiple cameras, or using a dedicated camera that contains multiple camera lenses embedded into the device, and filming overlapping angles simultaneously. Through a method known as video stitching, this separate footage is merged together into one spherical video piece, and the colour and contrast of each shot is calibrated to be consistent with the others. This process is done either by the camera itself, or using specialized video editing software that can analyze common visuals and audio to synchronize and link the different camera feeds together. Generally, the only area that cannot be viewed is the view toward the camera support. It is then rendered at high resolution – most commonly at 4K resolution – with positional or binaural sound to ensure the most immersive experience possible.
Specialized omnidirectional cameras and rigs have been developed for the purpose of filming 360-degree video, including rigs such as GoPro's Omni and Odyssey, the Nokia OZO, the Facebook Surround 360, the Kodak Pixpro SP360 4K Dual Pack Pro and the Axon's AZilPix Studio.One (all of which consist of multiple cameras installed into a single rig), the Vuze camera, handheld dual-lens cameras such as the Ricoh Theta S, Samsung Gear 360, Garmin VIRB 360, and the Kogeto Dot 360—a panoramic camera lens accessory developed for the iPhone 4, 4S, and Samsung Galaxy Nexus. In videoconferencing, 360° cameras are used, so that all participants on one location can be recorded with one camera. In Dec 2016, 360/VR specialist Orah. started shipping its 4K Live VR camera called Orah 4i.
Due to the newness of the technology, developer communities have begun to be developed around the various cameras, including the RICOH THETA Unofficial Guide, the Samsung Developer Program, LG Friends Developer, and more.
Most 360-degree video is monoscopic (2D), meaning that it is viewed as a one (360x180 equirectangular) image directed to both eyes. Stereoscopic video (3D) is viewed as two distinct (360x180 equirectangular) images directed individually to each eye. 360-degree videos are typically viewed via personal computers, mobile devices such as smartphones, or dedicated head-mounted displays. When viewed on PCs, the mouse is typically used to pan around the video by clicking and dragging. On smartphones, internal sensors such as the gyroscope are used to pan the video based on the orientation of the device. Taking advantage of this behavior, devices such as Google Cardboard viewers and the Samsung Gear VR serve as stereoscope-style headset enclosures that a smartphone can be inserted into, for viewing this content in a virtual reality format. They emulate the operation of a dedicated head-mounted display, but utilizing the display of the phone itself and internal lenses, rather than containing dedicated screens of their own.
In March 2015, YouTube officially launched the ability for users to view and upload 360-degree videos, with playback on its website and its Android mobile apps. Vimeo, another platform for video hosting, launched support for 360-degree video in March, 2017. Parent company Google also announced that it would collaborate with camera manufacturers to make it easier for creators to upload 360-degree content recorded with their products to YouTube. Facebook (parent company of VR headset maker Oculus VR) followed suit by adding 360-degree video support in September 2015. Other 360-degree video companies include Vrideo, Littlstar, Jaunt, and VRSE (now Within).
Google Cardboard, which is typically distributed in the form of do-it-yourself kits consisting of low-cost materials and components, has been credited with helping virtual reality become more readily available to the general public, and helping boost the adoption of 360-degree video by publishers, such as mainstream journalists and media brands.
Many 360-degree videos are labelled as 3D or VR, but some experts argue that these terms should be used more narrowly. If after stitching there is only one 360x180 equirectangular image then the resulting video is 2D and not 3D. It takes two distinct 360x180 equirectangular images to make a 3D video. For this reason, most content labelled as 3D is not 3D. Likewise, representations of reality made using a computer do not necessarily include any virtual simulations for the viewer. As a result of these ambiguities, the term VR should only be used if the content is indeed virtual.
|3D video||360-degree video||Interactive Virtual Reality|
|Characteristics||a view with depth of field||360-degree immersive view, look in different directions||
|Experience||immersed spectator||immersed spectator||active participant|
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