Omnidirectional (360-degree) camera
In photography, an omnidirectional camera (from "omni", meaning all), also known as 360-degree camera, is a camera having a field of view that covers approximately the entire sphere or at least a full circle in the horizontal plane. Omnidirectional cameras are important in areas where large visual field coverage is needed, such as in panoramic photography and robotics.
A camera normally has a field of view that ranges from a few degrees to, at most, 180°. This means that it captures, at most, light falling onto the camera focal point through a hemisphere. In contrast, an ideal omnidirectional camera captures light from all directions falling onto the focal point, covering a full sphere. In practice, however, most omnidirectional cameras cover only almost the full sphere and many cameras which are referred to as omnidirectional cover only approximately a hemisphere, or the full 360° along the equator of the sphere but excluding the top and bottom of the sphere. In the case that they cover the full sphere, the captured light rays do not intersect exactly in a single focal point.
Various techniques can be used to generate 360-degree images.
Cameras with one lens
These models are used with a fisheye lens. The lens bends the angle of the shot to take a larger radius of the selected subject. It is not possible to take a complete 360-degree picture with this technique because there is always a dead angle directly behind the lens.
Cameras with two lenses (Dual Fisheye)
360-degree cameras with two lenses are probably the most common type, as they can accommodate a full 360-degree angle with two lenses facing each other. A camera takes pictures and videos with an angle of just over 180 degrees, e.g. 220 degrees. These are then converted into a 360-degree object using software. Problems are often caused by stitching errors. This means that an incorrect combination of the images can result in an unclean cut edge that is difficult or impossible to remove.
Cameras with more than two lenses
Depending on the application, manufacturers use more than two camera lenses to produce the images. One of the first cameras was the throwing camera, Panono. It has 36 cameras, which are triggered at the same time at the highest point, if the camera was thrown into the air. The more lenses are installed in the camera, the more difficult it becomes for the software to combine the individual images, however, the possible stitching problems are less with a good stitching.
Camera rigs are mostly used for the attachment of 6 conventional Actioncams. GoPro produced one of the first camera rigs. They are available in different versions and connect several single cameras. The cameras are placed in this cube and record the surroundings in all directions.
Mosaic based cameras
If several "normal" cameras are combined in a network, one speaks of mosaic-based cameras. Each of these cameras records a small area of the environment. The individual images are then joined together like mosaic stones to form an omnidirectional overall image. The number of cameras to be used depends on the focal length of the lenses used. The smaller the focal length, the larger the angle of view and the fewer cameras are required.
Traditional approaches to panoramic photography mainly consists of stitching shots taken separately into a single, continuous image. The stitching of images, however, is computationally intensive (for example using the RANSAC iterative algorithm, commonly used to solve the correspondence problem), and depending upon the quality and consistency of the shots used, the resulting image might contain a number of deficiencies which impair the quality of the resulting image. In contrast, an omnidirectional camera can be used to create panoramic art in real time, without the need for post processing, and will typically give much better quality products.
Robotics and computer vision
In robotics, omnidirectional cameras are frequently used for visual odometry and to solve simultaneous localization and mapping (SLAM) problems visually. Due to its ability to capture a 360-degree view, better results can be obtained for optical flow and feature selection and matching.
Applications of omnidirectional cameras also include 3D reconstruction and surveillance, when it is important to cover as large a visual field as possible. Microsoft RoundTable was introduced in 2007 for videoconferencing, where all participants on one location can be in the same image.
Several implementations of omnidirectional (360-degree) cameras exist, including two opposing fisheye lens configurations and cameras with more than 30 separate lenses.
There have been fly-by-night companies that have produced prototypes and collected 'backers' on Kickstarter but have not delivered to end-users.
More established 360-camera manufacturers currently actively producing and supporting hardware as of March 2020 include:
- Red Digital Cinema
- 360 panorama
- 360-degree video
- Immersive video
- Light-field camera
- MSG Sphere
- Multiple-camera setup
- Panoramic tripod head
- Stereo camera
- VR photography
- Whole sky camera
- Parry, T. (December 2016). "Extensive Guide to 360 Cameras". Tim Parry. Retrieved 2017-01-02.
- "The GoPro 360 degree camera rig - Connect Omni Rig with 6 Actioncams". 360 Grad Kamera (in German). 2017-04-23. Retrieved 2019-02-11.
- "Cars with 360 camera".
- Scaramuzza, D.; Siegwart, R. (October 2008). "Appearance-Guided Monocular Omnidirectional Visual Odometry for Outdoor Ground Vehicles". IEEE Transactions on Robotics. 24 (5): 1015–1026. doi:10.1109/TRO.2008.2004490. hdl:20.500.11850/14362. S2CID 13894940.
- Ulrich, I.; Nourbakhsh, I. (2000). "Appearance-based place recognition for topological localization" (PDF). Proc IEEE Int Conf Rob Autom. 2: 1023–1029. Retrieved 2008-07-15.
- Kim, J.H.; Chung, M.J. (2003). "Slam with omni-directional stereo vision sensor". Intelligent Robots and Systems, 2003.(IROS 2003). Proceedings. 2003 IEEE/RSJ International Conference on. 1. doi:10.1109/IROS.2003.1250669.
- Jogan, M.; Leonardis, A. (2000). Robust localization using panoramic view-based recognition. 15th ICPR. 4. pp. 136–139. CiteSeerX 10.1.1.136.4931. doi:10.1109/ICPR.2000.902882. ISBN 978-0-7695-0750-7. S2CID 3178789.
- Bunschoten, Roland, and Ben Krose. "Robust scene reconstruction from an omnidirectional vision system." IEEE Transactions on Robotics and Automation 19.2 (2003): 351-357.
- Francesco Flammini; Roberto Setola; Giorgio Franceschetti (10 June 2013). Effective Surveillance for Homeland Security: Balancing Technology and Social Issues. CRC Press. ISBN 978-1-4398-8325-9.
- "Bublcam: 360º Camera Technology for Everyone". Kickstarter. Retrieved 2020-03-22.
- Zhang, Michael (2018). "RED and Facebook Unveil Manifold, a 3D and 360° VR Camera | PetaPixel". petapixel.com. Retrieved 2021-07-20.
- "Shop". Ricoh. Retrieved 2020-03-22.
- www.insta360.com https://www.insta360.com/. Retrieved 2020-03-22. Missing or empty
- "MAX 360 Camera | Max HyperSmooth, Max TimeWarp, Max SuperView | GoPro". gopro.com. Retrieved 2020-03-22.
- "MADV-Fuel Your Adventure". www.madv360.com. Retrieved 2020-03-22.
- "Home Page | Vuze Camera". vuze.camera. Retrieved 2020-03-22.
- "Panono 360 Camera 16K | Panono". www.panono.com. Retrieved 2020-03-22.
- "KanDao - 360 VR Camera | 3D Camera | 3D 360 Camera | 3D VR Camera". Kandao Tech. Retrieved 2020-03-22.
- "Z CAM - Professional Camera Company". Z CAM. Retrieved 2020-03-22.
- "Fm360.8K – FXG".
- "The race for the first 8K consumer 360 camera just got real thanks to this new sensor". 360 Rumors. 2019-08-13. Retrieved 2020-03-22.
- WHICH 360 CAMERA SHOULD YOU BUY IN 2020?, retrieved 2020-03-22
- Blumenthal, Eli. "How Madison Square Garden Co. is aiming to make every seat the best in the house". USA TODAY. Retrieved 2021-07-20.
|Wikimedia Commons has media related to Omnidirectional cameras.|