HoloKit
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| HoloKit | |
|---|---|
| Basic Info | |
| VR/AR | Augmented Reality |
| Type | Head-mounted display |
| Subtype | Phone-Powered AR |
| Creator | Botao Hu, Fengyuan Zhu, Yang Liu |
| Developer | Amber Garage |
| Announcement Date | 1 June 2017 (Augmented World Expo) |
| Release Date | 2017 |
| Price | US$30 (2017) |
| Website | https://1.holokit.io/ |
| Versions | HoloKit (2017, cardboard); HoloKit X (2022, plastic) |
| Requires | Smartphone (iPhone 7 and 7 Plus, Google Pixel and Project Tango phones at launch; later ARKit and ARCore phones) |
| Successor | HoloKit X |
| Image | |
| Field of View | 76 degrees diagonal |
| Optics | |
| Optics | Two mirrors reflecting the phone display onto an angled, semi-transparent Fresnel lens (optical see-through) |
| Tracking | |
| Tracking | Inside-out, using the phone's camera and inertial sensors |
| Device | |
| Material | Cardboard |
HoloKit is a cardboard AR headset for smartphones.[1] Instead of blocking out the room like a Google Cardboard viewer, it reflects the phone's screen onto a see-through lens, so virtual objects appear on top of the real world while the phone's camera and sensors track the wearer's position.[1] The name is also used for its plastic successor, HoloKit X, released in 2022,[2] which works with the iPhone only.[3]
HoloKit was created by Botao Hu, founder of the Silicon Valley studio Amber Garage, and was presented at the Augmented World Expo in June 2017.[4] The project describes itself as open source: the tracking software and the do-it-yourself hardware instructions were published, although the original license did not allow others to mass-produce and sell the headset without Amber Garage's permission.[4][5] HoloKit X is made by Holo Interactive, a New York company also founded by Hu, and sells for US$129.[6][7]
History
HoloKit (2017)
Amber Garage launched HoloKit on 1 June 2017 at the Augmented World Expo. The package consisted of the HeadKit cardboard headset and the TrackKit software. Amber Garage's credits list Hu, Fengyuan Zhu and Yang Liu as the creators of HoloKit 1.[5] TechCrunch described it as a low-cost option for testing or deploying augmented reality applications, compared with Microsoft HoloLens.[1] Early reports differed on availability: Gizmodo wrote that the headset and its open-source tracking software would be released on GitHub on 6 June 2017, while TechCrunch reported that ready-to-assemble kits were expected from July.[8][1]
Synced reported a price of US$30 and compared it with the Meta 2 (US$945) and HoloLens (US$3,000).[4] Hu told Synced: "HoloKit is our gift to the AR/MR industry. You can think of this project as a social experimental project of academia and art." Synced also reported that some Chinese media had run headlines claiming a US$30 HoloKit could beat a US$3,000 HoloLens, which drew skepticism on social media. Hu responded that "a low-cost component is not our core competence. The technology behind the software is the key."[4]
The first supported phones were the iPhone 7 and 7 Plus, Google Pixel phones and Project Tango hardware.[1] The HoloKit Unity SDK first had separate versions for Tango, ARKit and ARCore. Version 1.5 combined ARKit and ARCore support in one package; its changelog dates ARCore 1.0 and ARKit 1.5 beta support to 23 February 2018.[9] The HoloKit 1 website later listed ARKit iPhones from the iPhone 6s and SE to the iPhone 11 Pro Max, plus ARCore phones such as the Pixel 3 and Galaxy S10.[5] The SDK repository is now archived and marked as deprecated.[9]
HoloKit X (2022)
Holo Interactive released HoloKit X in 2022. The company calls it a "premium-quality upgrade" of the original "periscope-shaped" HoloKit 1, which it describes as a "cardboard proof of concept".[2] MIXED reported the product on 1 November 2022, when it cost US$129. At that time the hardware was final, the software was still in development, and the team of about ten people planned to publish the HoloKit app on the App Store at the end of November.[10] AppleInsider wrote that the app was released in December 2022.[11] As of September 2026, Holo Interactive sells HoloKit X for US$129, or US$249 for a two-headset bundle.[6]
Design and hardware
Optics
HoloKit uses optical see-through optics rather than showing a camera feed. In the cardboard version, mirrors reflect the smartphone display onto an angled, semi-transparent Fresnel lens, so the wearer sees the rendered image and the real surroundings at the same time.[1] Synced described the optics as a semipermeable membrane and a Fresnel lens.[4] Amber Garage gave the field of view as 76 degrees diagonal.[5] Synced compared this with 90 degrees for Meta 2 and 34 degrees for HoloLens.[4]
The phone sits on top of the headset in a periscope-style layout. Synced noted that this moves the center of gravity forward, so the cardboard HoloKit is not hands-free and has to be held at all times.[4] Gizmodo noted that, like Cardboard, it has no head strap.[8]
HoloKit X keeps the top-mounted phone, with the iPhone's display reflected into view from above.[10] Holo Interactive specifies a 60-degree field of view and says its lenses give near-zero distortion.[12] The plastic headset has a fabric head strap and fits over most eyeglasses.[11][12][13] According to MIXED, the only electronic part in the holder is an NFC sensor; the iPhone does everything else.[10] Holo Interactive says the NFC chip is used for anti-counterfeit authentication.[13]
Tracking
The cardboard HoloKit uses inside-out tracking based on the phone.[4] Synced reported that its method, called a "monocular visual-inertial state estimator for mobile phones", combines a rolling-shutter camera with the phone's inertial measurement unit. It traced the technique to Shaojie Shen of the Hong Kong University of Science and Technology and said Hu's role was applying it to AR.[4] The HoloKit GitHub organization hosts an archived fork of VINS-Mobile, a monocular visual-inertial odometry system from the HKUST Aerial Robotics Group that runs on iOS devices and provides localization for AR applications.[14] With the later SDK, tracking came from Apple's ARKit or Google's ARCore instead.[9]
HoloKit X relies on the iPhone's own AR features. Holo Interactive lists 6DoF tracking through ARKit, environment sensing with the iPhone LiDAR scanner, hand tracking through Apple's Vision framework recognizing up to 21 hand joints, and haptic feedback from the iPhone's Taptic Engine felt through the forehead.[12]
Specifications
| Specification | HoloKit (2017) | HoloKit X (2022) |
|---|---|---|
| Material | Cardboard[8] | Plastic with a grey metallic finish[11] |
| Field of view | 76 degrees diagonal[5] | 60 degrees[12] |
| Optics | Two mirrors and an angled semi-transparent Fresnel lens[1] | Optical see-through lenses[12] |
| Head strap | None[8] | Replaceable headband[13] |
| Size (without strap) | Not published | 100 mm high, 133 mm wide, 140 mm deep[13] |
| Weight | Not published | 215 grams (7.6 oz)[13] |
| Phones | iPhone, Google Pixel, Tango and later ARKit and ARCore phones[1][5] | iPhone only[3] |
| Price | US$30[4] | US$129[6] |
Compatible phones for HoloKit X
Holo Interactive says HoloKit X "works primarily with iPhones with LiDAR Scanner", listing the iPhone 12 Pro and Pro Max through the iPhone 15 Pro and Pro Max. It gives secondary support to iPhones with OLED screens, from the iPhone X to the iPhone 14. It says iPhones with LCD screens (326 ppi) do not have enough pixel density, and that iPhones older than the iPhone X, and the 12 mini and 13 mini, have screens too small to fit.[15]
Software and features
For the cardboard headset, Amber Garage published a HoloKit app for iOS and Android and the HoloKit SDK for developers.[5] The HoloKit 1 Unity SDK, released under the Apache 2.0 license, handled stereoscopic rendering, per-phone calibration profiles, switching between AR and mixed reality modes, screen brightness control and a shared wrapper for ARKit and ARCore.[9] Amber Garage's license allowed anyone to build commercial or non-commercial apps for HoloKit and to modify the hardware for non-commercial use. It did not allow mass production and sale of the headset without the company's permission.[5]
HoloKit X uses the HoloKit Unity SDK, which is published on GitHub under the MIT license, along with sample projects such as a co-located multiplayer template.[16] Holo Interactive promotes the product for shared, co-located use. Nearby users can share the same digital content, and a spectator can watch through another iPhone or iPad or stream the view over AirPlay.[12][3] An Apple Watch can be used as a motion controller.[12] MIXED reported that the AirDrop feature is used for local multiplayer games and for a spectator view, and that spatial sound works with suitable headphones.[10]
At the time of AppleInsider's review, the HoloKit app contained three game modes built around wizard duels (against a computer opponent, against other HoloKit users, and against a dragon) and eight other AR demonstrations.[11] Holo Interactive describes the product as meant for creators, researchers and educators, and positions it as the mixed reality equivalent of Arduino.[17]
Research use
Hu and co-authors used HoloKit X in research on co-located mixed reality play. Their paper on "Immersive Mixed Reality Street Play", accepted at CSCW 2025, studied the game Multiplayer Omnipresent Fighting Arena (MOFA) in public places. The game ran as an iOS app built with Unity and the HoloKit SDK on iPhone 12 or newer phones placed in HoloKit, and players cast spells with an Apple Watch. The authors chose HoloKit because of its US$129 price, which made it possible for many passers-by to take part.[18] One participant quoted in the paper said: "This (HoloKit with iPhone) is (yet) not the form factor that will change the paradigm, the smartphone is."[18]
Reception
Writing about the cardboard version, Gizmodo called it "a big step down from an actual Hololens" and said it was hard to judge from video whether the image would look "totally bootleg".[8] Synced's reviewer found the blending of a virtual character with the real room "visually acceptable" and did not experience dizziness during the demo.[4]
AppleInsider gave HoloKit X 2.5 out of 5 in February 2023. The reviewer found the headset well built and comfortable with glasses and said the lenses showed no distortion. The review criticized buggy multiplayer, a small selection of AR experiences and uncertainty about further development, and recommended waiting "at least a few months" before buying.[11] MIXED cited a Wired hands-on that called the image "clear, colorful and quite sharp".[10]
HoloKit X won a Red Dot Design Award in the Product Design category in 2023. Red Dot lists Holo Interactive of New York as the manufacturer, with in-house design by Hu's team and external design by the Seoul studio Second White.[19] Holo Interactive also lists an iF Design Award 2024 and two Core77 Design Awards 2023, and says the design was nominated for the 2023 Webby Awards and SXSW 2023 Innovation Awards.[20]
See also
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Coldewey, Devin (2017-06-02). "HoloKit is like Google Cardboard for augmented reality". TechCrunch. https://techcrunch.com/2017/06/02/holokit-is-like-google-cardboard-for-augmented-reality/. Retrieved 2024-05-19.
- ↑ 2.0 2.1 "HoloKit X". HoloKit Docs. Holo Interactive. https://docs.holokit.io/product/holokit-x. Retrieved 2026-09-27.
- ↑ 3.0 3.1 3.2 "About the Product". HoloKit Docs. Holo Interactive. https://docs.holokit.io/about/media-inquiry/fact-sheet/about-the-product. Retrieved 2026-09-27.
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 Tony Peng (2017-08-22). "A $30 AR Headset?". Synced. https://syncedreview.com/2017/08/22/a-30-ar-headset/. Retrieved 2026-09-27.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 "HoloKit - Open Source Mixed Reality for Everyone". HoloKit. Amber Garage. https://1.holokit.io/. Retrieved 2026-09-27.
- ↑ 6.0 6.1 6.2 "HoloKit - Open-Source AR Headset for Creative Spatial Computing". HoloKit. Holo Interactive. https://holokit.io/. Retrieved 2026-09-27.
- ↑ "About the Company". HoloKit Docs. Holo Interactive. https://docs.holokit.io/about/media-inquiry/fact-sheet/about-the-company. Retrieved 2026-09-27.
- ↑ 8.0 8.1 8.2 8.3 8.4 Rhett Jones (2017-06-03). "Make Your Own Bootleg HoloLens With the Cardboard Holokit". Gizmodo. https://gizmodo.com/make-your-own-bootleg-hololens-with-the-cardboard-holok-1795784864. Retrieved 2026-09-27.
- ↑ 9.0 9.1 9.2 9.3 "holokit-1-sdk: HoloKit Unity SDK for HoloKit 1 (Cardboard version)". GitHub. HoloKit. https://github.com/holokit/holokit-1-sdk. Retrieved 2026-09-27.
- ↑ 10.0 10.1 10.2 10.3 10.4 Tomislav Bezmalinovic (2022-11-01). "Holokit X turns your iPhone into AR headset". MIXED. https://mixed-news.com/en/holokit-x-turns-your-iphone-into-ar-headset/. Retrieved 2026-09-27.
- ↑ 11.0 11.1 11.2 11.3 11.4 Thomas Sibilly (2023-02-08). "Holokit X Review: Still-developing stereoscopic AR". AppleInsider. https://appleinsider.com/articles/23/02/08/holokit-x-review-still-developing-stereoscopic-ar. Retrieved 2026-09-27.
- ↑ 12.0 12.1 12.2 12.3 12.4 12.5 12.6 "HoloKit X - A Stereoscopic AR Headset for iPhone". HoloKit. Holo Interactive. https://holokit.io/pages/holokit-x. Retrieved 2026-09-27.
- ↑ 13.0 13.1 13.2 13.3 13.4 "Specifications". HoloKit Docs. Holo Interactive. https://docs.holokit.io/product/holokit-x/specifications. Retrieved 2026-09-27.
- ↑ "VINS-Mobile: Monocular Visual-Inertial State Estimator on Mobile Phones". GitHub. HoloKit. https://github.com/holokit/VINS-Mobile. Retrieved 2026-09-27.
- ↑ "Compatible iPhones". HoloKit Docs. Holo Interactive. https://docs.holokit.io/product/holokit-x/compatible-iphones. Retrieved 2026-09-27.
- ↑ "HoloKit". GitHub. https://github.com/holokit. Retrieved 2026-09-27.
- ↑ "About us". HoloKit Docs. Holo Interactive. https://docs.holokit.io/about/about-us. Retrieved 2026-09-27.
- ↑ 18.0 18.1 Botao Amber Hu, Rem Rungu Lin, Yilan Elan Tao, Samuli Laato, Yue Li (2025-05-18). "Towards Immersive Mixed Reality Street Play: Understanding Co-located Bodily Play with See-through Head-mounted Displays in Public Spaces". arXiv (accepted at CSCW 2025). doi:10.1145/3757679. https://arxiv.org/abs/2505.12516. Retrieved 2026-09-27.
- ↑ "HoloKit X". Red Dot Design Award. Red Dot. 2023. https://www.red-dot.org/project/holokit-x-64930. Retrieved 2026-09-27.
- ↑ "Awards". HoloKit Docs. Holo Interactive. https://docs.holokit.io/about/awards. Retrieved 2026-09-27.