Slide-on HMD
More actions
Slide-on HMD, also known as Smartphone mount, is the cheapest and most accessible form of virtual reality head-mounted display. The Slide-on consists of a smartphone holder, lenses and some form of basic input. A smartphone is inserted into the HMD and the entire device is placed upon the eyes of the user to create the VR experience. The Slide-on utilizes the smartphone for display, processing and rotational tracking. Some Slide-on HMDs such as the Gear VR use their own built-in IMUs instead of relying on that of the smartphones. This method allows the HMD to create a superior tracking experience for the user.[1][2]
In research papers the same devices are also called smartphone-based head-mounted displays.[3][4] The format reached a mass audience through Google Cardboard, announced in 2014, and the Samsung Gear VR, developed with Oculus VR. Google's Cardboard program had shipped more than 15 million viewers by November 2019.[5] Google stopped selling its Daydream View headset in October 2019, and Oculus stopped accepting new Gear VR apps in September 2020.[6][7]
How it works
Display and optics
Magnifying lenses in the viewer sit between the phone's screen and the user's eyes.[8] The 2012 FOV2GO kit from the University of Southern California used software that displayed stereo images from the Unity game engine on the phone.[9] Google's manufacturer guidance for Cardboard viewers says that lenses with a 45 mm focal distance "might work" and that biconvex lenses work best because they prevent distortion around the edges.[10]
Simple magnifying lenses distort the image, so the phone pre-warps each frame in software. The Google VR SDK describes its correction with a radial polynomial, p' = p (1 + K1 r^2 + K2 r^4 + ... + Kn r^(2n)), where r is the distance from the optical center and the coefficients Ki correspond to the pincushion distortion equation.[11] Because every third-party viewer has different optics, Google offers a Viewer Profile Generator: a manufacturer enters the viewer's parameters and prints the result as a QR code on the viewer, and Cardboard apps read the code and adapt their rendering to that viewer.[10] The open-source Cardboard SDK released in 2019 contains the head tracking, lens distortion rendering and input handling code, plus a QR code library for pairing viewers.[5]
Tracking
Consumer smartphone VR systems track only head rotation (three degrees of freedom).[12] Cardboard apps track head movement with the phone's own accelerometers and gyroscopes.[8] On the first Cardboard the phone's magnetometer also detected the magnetic input ring; Google's second-generation design freed the magnetometer from that job so it could help keep the virtual view from drifting.[13]
The Gear VR took a different approach. Oculus described the Innovator Edition as having the "Oculus Tracker and firmware built into the headset" for low-latency 3DOF tracking, and quoted a motion-to-photon latency under 20 milliseconds, while the phone's CPU and GPU did the rendering.[1] Engadget's review of the 2015 consumer model noted an accelerometer, a gyroscope and proximity sensors in the headset "to reduce latency and increase the performance overall".[2] None of these consumer headsets offered positional tracking, so users could not lean in or duck to change their viewpoint.[2][14]
Input
Input methods changed with each generation. The first Cardboard used a metal ring held on the side of the viewer by a magnet; flicking it downward acted as a trigger that the phone detected through its magnetometer.[8] The 2015 Cardboard replaced the magnet with a button that Google said would work with all phones.[13] The Gear VR had a touchpad on the side of the headset for swipes and taps, and Samsung sold an optional Bluetooth controller in a US$249 bundle with the Innovator Edition.[15] Google's Daydream View shipped with a motion-sensing controller that also tracked three degrees of freedom.[14]
History
Early viewers
Researchers at the Mixed Reality (MxR) Lab of the USC Institute for Creative Technologies, working with the USC School of Cinematic Arts, built the FOV2GO, a fold-out paper viewer that turned an iPhone or Android phone into a 3D virtual reality display. It cost less than US$5 to construct, and the lab handed out hundreds of them in manila envelopes at the IEEE Virtual Reality conference in March 2012, starting at the Workshop on Off-The-Shelf Virtual Reality on 4 March.[9] The lab's poster at that conference described training games that ran entirely on commodity smartphones, an off-the-shelf game engine and mass-produced optics, and suggested the setup for casual "pick up and use" VR in classrooms and design reviews.[3] According to the institute, the MxR Lab won the IEEE VR Best Demo Award that year.[16] A 2013 paper from the lab listed its open-source projects, including the VR2GO smartphone viewer, the inVerse tablet viewer and a repurposed FOV2GO design used with Nokia Lumia phones in a 3D user interface course at Columbia University; the same abstract listed the Oculus Rift among the projects spun out of the lab's efforts.[17]
Google Cardboard
Cardboard started as a "20% time" project by David Coz and Damien Henry at the Google Cultural Institute in Paris.[18] Google gave the viewers to attendees of its I/O developer conference in June 2014. The kit was folded corrugated cardboard with magnifying lenses, a metal ring trigger and a rubber band to hold the phone, and the companion app included 360-degree photo panoramas and a YouTube viewer.[8] Road to VR reported that Google handed out about 6,000 kits at I/O and saw 50,000 to 100,000 app downloads in the first week; Google's Christian Plagemann called the viewer "just a placeholder".[18]
The second version, given to I/O attendees in May 2015, fit phones with screens up to 6 inches and assembled in three steps instead of twelve. Google did not sell either version itself at first and left manufacturing to third parties.[13] In February 2016 it began selling Cardboard directly through its online Google Store at US$15 for one viewer or US$25 for two.[19] Mattel and Google announced a plastic, Cardboard-based View-Master viewer in February 2015 at a price of US$30, with reel packs at US$12 for four.[20]
On 6 November 2019 Google said Cardboard had shipped more than 15 million units, that overall usage had declined over time, and that it was releasing the Cardboard software as an open-source project for Android and iOS.[5] Engadget described the move as part of Google's retreat from phone-based VR.[21]
Samsung Gear VR
Samsung and Oculus announced the Gear VR Innovator Edition on 3 September 2014 as an add-on for the Galaxy Note 4, whose 5.7-inch 1440p AMOLED screen served as the display.[1] It went on sale in the US on 8 December 2014 for US$199 through Samsung and AT&T.[15] At Oculus Connect 2 on 24 September 2015, the companies announced a consumer edition for US$99, compatible with the Galaxy Note 5, S6 edge+, S6 and S6 edge, with a US launch in November and more than 40 other countries to follow.[22] Later models are covered at Samsung Gear VR (2015/2016) and Samsung Gear VR (2017).
Samsung dropped VR support on the Galaxy Note 10 and Galaxy S20.[23] In March 2020 Oculus announced that from 15 September 2020 developers could no longer create new Gear VR apps, although existing apps could still be updated and downloaded from the Gear VR store.[7] On 31 March 2020 UploadVR reported that Samsung phones would no longer receive new Gear VR features through Oculus software updates, and that the Oculus Video and Oculus 360 Photos apps could no longer be downloaded on Gear VR.[23]
Google Daydream View
Google announced the Daydream View on 4 October 2016 at US$79, including its controller, for release in November 2016. It had a fabric exterior and, unlike the Gear VR, connected to the phone wirelessly instead of through a data port.[14] On 15 October 2019 Google stopped selling the headset and said the Pixel 4 would not support Daydream, while the Daydream app and store remained available to existing users.[6]
Notable slide-on HMDs
| Viewer | Maker | Announced or released | Launch price | Input |
|---|---|---|---|---|
| FOV2GO | USC Institute for Creative Technologies | March 2012 (IEEE VR) | Under US$5 to build[9] | Not stated |
| Google Cardboard (first version) | June 2014 (Google I/O) | Free to I/O attendees[8] | Magnetic ring[8] | |
| Samsung Gear VR Innovator Edition | Samsung and Oculus VR | Announced September 2014; on sale December 2014 | US$199[15] | Touchpad; optional Bluetooth controller[15] |
| Google Cardboard (second version) | Google and third-party makers | May 2015 (Google I/O) | US$15 in the Google Store from February 2016[19] | Button[13] |
| View-Master VR | Mattel with Google | Announced February 2015 | US$30[20] | Not stated |
| Samsung Gear VR (consumer edition) | Samsung and Oculus VR | Announced September 2015; US launch November 2015 | US$99[22] | Touchpad[2] |
| Daydream View | Announced October 2016 | US$79 with controller[14] | Motion controller[14] |
Cost
Slide-on HMDs are often the cheapest form of VR if the user excludes the cost of the smartphone. Google Cardboard can be built or purchased for under $20; Google sold its own viewer for US$15 in 2016.[19] The consumer Samsung Gear VR sold for US$99 at its November 2015 launch.[22] Google's build-it-yourself guidance lists corrugated cardboard, two lenses, magnets, hook-and-loop fastener, a rubber band and an optional NFC tag as the parts for a homemade viewer.[10]
Limitations
Because the display is an ordinary phone screen held close to the eyes, individual pixels can be visible. Engadget's 2015 Gear VR review reported a screen door effect in which individual pixels could be seen (less pronounced than on earlier Gear VR models), a battery drop of about 20 percent after an hour of use, and occasional overheating during long sessions.[2] The lack of positional tracking limited what applications could do.[2]
When Google ended Daydream, it said it had "noticed some clear limitations constraining smartphone VR from being a viable long-term solution", and that "asking people to put their phone in a headset and lose access to the apps they use throughout the day causes immense friction".[6] In its report on the end of Gear VR updates, UploadVR noted that John Carmack had said the standalone Oculus Go saw Rift-like user retention, while Gear VR retention was much lower.[23]
Applications
Slide-on viewers were distributed in large numbers for education and media. Google's Expeditions Pioneer Program, launched in 2015, brought kits to schools in the United States, Australia, the United Kingdom and Brazil; each kit contained Asus Zenfone 2 phones, a tablet for the teacher, a router for offline use and Cardboard or View-Master viewers, so a teacher could lead a whole class on a synchronized virtual field trip.[24] In journalism, The New York Times sent more than one million Cardboard viewers to its home delivery subscribers on the weekend of 7 November 2015 to go with its new VR app.[25] The viewers arrived with the Times' VR film The Displaced, which tells the stories of three refugee children forced from their homes by war or persecution.[26] Google said in 2019 that Cardboard still saw consistent use for entertainment and education through apps such as YouTube and Expeditions.[5]
Research
Smartphone-based HMDs have also been studied directly. In a 2017 study at the IEEE International Conference on Advanced Learning Technologies, Papachristos, Vrellis and Mikropoulos compared an Oculus Rift with a low-cost smartphone VR headset in an educational virtual environment and found no differences in spatial presence, usability, simulator sickness, satisfaction, workload or learning outcome.[27]
Tošić, Hoffman and Balram tested simulator sickness in smartphone VR at latencies of 18 ms and 28 ms during natural game play. They found differences between individuals but no significant difference across the whole sample.[12] A 2021 randomized controlled trial in Scientific Reports had 58 healthy volunteers play games for two hours on a Gear VR Innovator Edition with a Galaxy S6 and, on a different day, on a smartphone alone. After the VR sessions the researchers measured significant changes in near-point convergence and accommodation, exophoric deviation, stereopsis and accommodative lag, which they did not see after smartphone use; refraction and choroidal thickness did not change significantly with either device.[4]
Device list
| Devices | Requires | Display | Resolution | Refresh Rate | Field of View | Tracking | Rotational Tracking | Positional Tracking | Update Rate | Latency | Input | Connectivity |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Figment VR | Depends on the smartphone | Depends on the smartphone | 3DOF | IMUs in Smartphone | None | |||||||
| Impression Pi | Smartphone for Starter/Empower; Master proposed with built-in computing and display | Phone display for Starter/Empower; built-in display proposed for Master | Depends on phone for Starter/Empower | More than 90 degrees advertised in the 2015 campaign | 6DoF head tracking and hand tracking advertised for Core-equipped versions | Core board IMU and AHRS algorithm; campaign claims IMU sampling above 1,000 Hz | Inside-out camera-based tracking proposed; accuracy remained under development | Camera-based hand/finger tracking and gestures advertised for Core-equipped packages | Core-to-phone USB or Lightning proposed; Master 2.4/5 GHz Wi-Fi proposed | |||
| Mi VR Play | Smartphone; Xiaomi recommends a 4.7-5.7-inch display | Uses the smartphone display | Depends on the smartphone | Uses the phone's motion sensing | Top button makes conductive contact with phone touchscreen | |||||||
| Samsung Gear VR (2015/2016) | All Samsung Smartphones 2015 and newer | 5.7 / 5.1 inch Super AMOLED (RGBG PenTile) | 2560 x 1440, 1280 x 1440 per eye | 60 Hz | 96° (nominal) | 3DOF | Accelerator, Gyrometer, Proximity | None | Rotational: 1000 Hz, high accuracy | Motion to Photon: Less than 6 ms | Touchpad, Back Button, Volume Key, Focus adjustment wheel | microUSB to the smartphone |
| Samsung Gear VR Innovator Edition | Galaxy Note 4, Galaxy S6, Galaxy S6 Edge | 5.7 / 5.1 inch Super AMOLED (RGBG PenTile) | 2560 x 1440, 1280 x 1440 per eye | 60 Hz Low-persistence | 96° (nominal) | 3DOF | Accelerator, Gyroscope, Magnetometer | None | Rotational: 1000 Hz, high accuracy | Motion to Photon: Less than 20 ms | Touch Pad, Back Button, Volume Key | microUSB to the smartphone |
| Wearality Sky | Smartphone | Depends on smartphone | Depends on smartphone | 150° | 3DOF | IMUs in Smartphone | None |
See also
References
- ↑ 1.0 1.1 1.2 Oculus VR (2014-09-03). "Introducing the Samsung Gear VR Innovator Edition". Oculus Blog. Meta. https://www.meta.com/blog/introducing-the-samsung-gear-vr-innovator-edition/. Retrieved 2026-09-27.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Nicole Lee (2015-11-25). "Samsung Gear VR review (2015): A no-brainer if you own a Samsung phone". Engadget. https://www.engadget.com/2015-11-25-samsung-gear-vr-review-2015.html. Retrieved 2026-09-27.
- ↑ 3.0 3.1 Perry Hoberman, David M. Krum, Evan A. Suma, Mark Bolas (2012-03). "Immersive training games for smartphone-based head mounted displays". 2012 IEEE Virtual Reality (VR), pp. 151-152. doi:10.1109/VR.2012.6180926. https://doi.org/10.1109/VR.2012.6180926. Retrieved 2026-09-27.
- ↑ 4.0 4.1 Hyeon Jeong Yoon, Hyun Sik Moon, Mi Sun Sung, Sang Woo Park, Hwan Heo (2021-07-28). "Effects of prolonged use of virtual reality smartphone-based head-mounted display on visual parameters: a randomised controlled trial". Scientific Reports, vol. 11. doi:10.1038/s41598-021-94680-w. https://doi.org/10.1038/s41598-021-94680-w. Retrieved 2026-09-27.
- ↑ 5.0 5.1 5.2 5.3 Jeffrey Chen (2019-11-06). "Open sourcing Google Cardboard". Google Developers Blog. Google. https://developers.googleblog.com/2019/11/open-sourcing-google-cardboard.html. Retrieved 2026-09-27.
- ↑ 6.0 6.1 6.2 Ben Lang (2019-10-15). "Google Discontinues Daydream View Headset, the Final Nail in the Coffin for its Android VR Ambitions". Road to VR. https://www.roadtovr.com/google-puts-final-nail-daydream-coffin-discontinues-view-headset/. Retrieved 2026-09-27.
- ↑ 7.0 7.1 "Gear VR Update: No Longer Accepting New Apps as of September 15, 2020". Meta Horizon OS Developers Blog. Meta. 2020-03-11. https://developers.meta.com/horizon/blog/gear-vr-update-no-longer-accepting-new-apps-as-of-september-15-2020/. Retrieved 2026-09-27.
- ↑ 8.0 8.1 8.2 8.3 8.4 8.5 Jared Newman (2014-06-26). "The Weirdest Thing at Google I/O Was This Cardboard Virtual Reality Box". Time. https://time.com/2925768/the-weirdest-thing-at-google-io-was-this-cardboard-virtual-reality-box/. Retrieved 2026-09-27.
- ↑ 9.0 9.1 9.2 "Out of the Box: USC Researchers Debut Smartphone 3-D Virtual Reality Viewer Made Out of Cardboard". USC Institute for Creative Technologies. 2012-03-05. https://ict.usc.edu/news/press-releases/out-of-the-box-usc-researchers-debut-smartphone-3-d-virtual-reality-viewer-made-out-of-cardboard/. Retrieved 2026-09-27.
- ↑ 10.0 10.1 10.2 "It's your turn to make it - Cardboard". Google for Developers. Google. https://developers.google.com/cardboard/manufacturers. Retrieved 2026-09-27.
- ↑ "Distortion - Google VR". Google for Developers. Google. https://developers.google.com/vr/reference/android/com/google/vr/sdk/base/Distortion. Retrieved 2026-09-27.
- ↑ 12.0 12.1 Ivana Tošić, David Hoffman, Nikhil Balram (2021). "Effect of latency on simulator sickness in smartphone virtual reality". Journal of the Society for Information Display, vol. 29, no. 7, pp. 561-572. doi:10.1002/jsid.999. https://doi.org/10.1002/jsid.999. Retrieved 2026-09-27.
- ↑ 13.0 13.1 13.2 13.3 Ben Lang (2015-05-28). "Google Announces New, Larger Cardboard VR Viewer with Universal Input Button". Road to VR. https://roadtovr.com/google-announces-new-larger-cardboard-vr-viewer-with-universal-input-button/. Retrieved 2026-09-27.
- ↑ 14.0 14.1 14.2 14.3 14.4 Lucas Matney (2016-10-04). "Google welcomes the future of mobile VR with its $79 Daydream View VR headset". TechCrunch. https://techcrunch.com/2016/10/04/google-welcomes-the-future-of-mobile-vr-with-its-daydream-view-vr-headset/. Retrieved 2026-09-27.
- ↑ 15.0 15.1 15.2 15.3 Kyle Russell (2014-12-08). "Samsung Gear VR Launches Today For $199". TechCrunch. https://techcrunch.com/2014/12/08/samsung-gear-vr-launches-today-for-199/. Retrieved 2026-09-27.
- ↑ David Nelson (2024-04-03). "A University in Every Garage". USC Institute for Creative Technologies. https://ict.usc.edu/news/essays/a-university-in-every-garage/. Retrieved 2026-09-27.
- ↑ Mark Bolas, Perry Hoberman, Thai Phan, Palmer Luckey, James Iliff, Nate Burba, Ian McDowall, David M. Krum (2013-03). "Open virtual reality". 2013 IEEE Virtual Reality (VR), pp. 183-184. doi:10.1109/VR.2013.6549423. https://doi.org/10.1109/VR.2013.6549423. Retrieved 2026-09-27.
- ↑ 18.0 18.1 Ben Lang (2014-07-01). "Google: 'Cardboard is a Placeholder,' 6,000 Kits and 50,000+ App Downloads in First Week". Road to VR. https://roadtovr.com/google-cardboard-virtual-reality-6000-kits-50000-app-downloads-first-week/. Retrieved 2026-09-27.
- ↑ 19.0 19.1 19.2 Elyse Betters Picaro (2016-02-29). "Google now sells Cardboard VR viewer directly through its online store". Pocket-lint. https://www.pocket-lint.com/apps/news/google/136905-google-now-sells-cardboard-vr-viewer-directly-through-its-online-store/. Retrieved 2026-09-27.
- ↑ 20.0 20.1 Christina Austin (2015-02-13). "Google, Mattel team up to give the iconic View-Master a makeover". Fortune. https://fortune.com/2015/02/13/google-mattel-view-master-makeover/. Retrieved 2026-09-27.
- ↑ Jon Fingas (2019-11-06). "Google open sources Cardboard as it retreats from phone-based VR". Engadget. https://www.engadget.com/2019-11-06-google-cardboard-open-source-project.html. Retrieved 2026-09-27.
- ↑ 22.0 22.1 22.2 "Oculus Connect 2: Consumer Gear VR, Minecraft, and more!". Oculus Blog. Meta. 2015-09-24. https://www.meta.com/blog/oculus-connect-2-consumer-gear-vr-minecraft-and-more/. Retrieved 2026-09-27.
- ↑ 23.0 23.1 23.2 David Heaney (2020-03-31). "Facebook Ends Samsung Gear VR Software Updates, 360 Video Downloads & Films". UploadVR. https://www.uploadvr.com/samsung-gear-vr-updates-end/. Retrieved 2026-09-27.
- ↑ Frederic Lardinois (2015-09-28). "Google's Expeditions Pioneer Program Brings Cardboard To Schools". TechCrunch. https://techcrunch.com/2015/09/28/googles-expeditions-pioneer-program-brings-cardboard-to-schools/. Retrieved 2026-09-27.
- ↑ Mathew Ingram (2015-10-20). "New York Times enters the world of virtual reality with Google partnership". Fortune. https://fortune.com/2015/10/20/nyt-google-cardboard/. Retrieved 2026-09-27.
- ↑ Rick Broida (2015-11-09). "What It Was Like to Watch the New York Times' VR Movie". Fortune. https://fortune.com/2015/11/09/new-york-times-virtual-reality/. Retrieved 2026-09-27.
- ↑ Nikiforos M. Papachristos, Ioannis Vrellis, Tassos A. Mikropoulos (2017-07). "A Comparison between Oculus Rift and a Low-Cost Smartphone VR Headset: Immersive User Experience and Learning". 2017 IEEE 17th International Conference on Advanced Learning Technologies (ICALT), pp. 477-481. doi:10.1109/ICALT.2017.145. https://doi.org/10.1109/ICALT.2017.145. Retrieved 2026-09-27.