HMD Position Acceleration
More actions
| HMD Position Acceleration | |
|---|---|
| Information | |
| Type | Seated, Standing, Room-scale |
| Required Devices | None |
| Description | Initiating movement by looking in the direction you want to go. You tilt your head forward, you move forward. Tilt your head backwards, and you go backwards. |
| Pros | Movement is started and steered by tilting the head; Crytek described it as fun and intuitive, especially with a visual aid[1] |
| Cons | Crytek reported that it "can be a bit nauseating"[1] |
| Creator | Crytek |
HMD Position Acceleration is a Locomotion Method. It is an artificial locomotion prototype for virtual reality (VR), developed by Crytek, in which the user starts moving by tilting the head in the direction they want to travel: tilting forward moves the user forward and tilting backward moves them backward.[1] Crytek presented it in 2017 as part of a series of locomotion experiments published with Oculus, and the method appears in Crytek's write-up under the names "HMD Acceleration" and "Head Tilt Acceleration".[2][1] The video demonstrating it on the Meta VR YouTube channel is titled "HMD Position Acceleration".[3]
Crytek game designer Julius Carter called the method "straight-up a lot of fun" but noted that it can be nauseating; he wrote that it was especially fun with a visual aid applied.[1] Academic studies have compared similar head-tilt and leaning interfaces with controller input and teleportation, measuring speed, presence and sickness.[4][5]
How it works
In Crytek's description, the user initiates movement "by looking in the direction you want to go". Tilting the head forward moves the user forward, and tilting it backward moves the user backward.[1] Crytek called the method "a combination of different prototypes". When it is combined with a separate "HMD strafing" prototype, tilting the head to the side moves the user sideways, and Crytek compared the result to being "a pinball on a table, rolling around" or moving through the world "like you're a snake".[1][6] In the Oculus video of the prototype, Carter tests the method in VR.[3] The blog post does not describe implementation details such as tilt thresholds or speeds.
Crytek suggested several combinations. It proposed an infinite runner game with obstacles and collection points that would pair head-tilt movement with its Charge Float Jump prototype, and it wrote that World Rotation, a controller-based turning method using Oculus Touch, combined with "Head Tilt Acceleration" and strafing, "has all the makings of a compelling VR first-person shooter experience".[1]
History
In May 2017 Oculus and Crytek began publishing "Developer Perspectives: VR Locomotion", a series of videos and blog posts presented by Julius Carter, a game designer in Crytek's research and development team.[7][8] Crytek said many of the methods it explored had made their way into its two Oculus Rift games, The Climb and Robinson: The Journey, and that it would share more than 40 videos covering different movements and actions.[8] When Road to VR reported on the first installment, seven videos had been published.[9]
Crytek did not run its tests in a plain white-box level. It built a large test environment designed to resemble a game level and filled it with features intended to provoke discomfort, including a carousel, an elevator that moves and accelerates up and down at random, a room that replicates the motion of a boat at sea, and platforms to jump from. Because testers quickly became used to VR, the team tried each prototype on many different people.[8]
The second post in the series, "Movement and Combinations", was published on the Oculus developer blog on 23 August 2017 and on the CRYENGINE site on 8 September 2017.[2][1][6] It singled out three methods from its video playlist as successful: Charge Float Jump, HMD Acceleration and World Rotation.[1] Road to VR described the accompanying playlist as showing eight prototype methods for moving and rotating in VR.[6] The description of the HMD Position Acceleration video places it in this "Movement and Combinations" series.[3]
Crytek's description
Crytek's full description of the method in the "Movement and Combinations" post reads:[1]
This movement is just straight-up a lot of fun. It's a combination of different prototypes, and it's a way of initiating movement by looking in the direction you want to go. You tilt your head forward, you move forward. Tilt your head backwards, and you go backwards. In combination with HMD strafing, you can also tilt your head to the side and together, it makes you feel like you're a pinball on a table, rolling around, or you can move through the world like you're a snake. While this functionality can be a bit nauseating, it's super fun, especially when you apply a visual aid. An infinite runner using this locomotion would be really interesting-put obstacles in the world, collection points, maybe add in Charge Float Jump functionality, and you can move rapidly and intuitively through VR.
Problems
Crytek reported that HMD Position Acceleration "can be a bit nauseating".[1] In its introduction to the locomotion series, Crytek wrote that acceleration in a VR environment can make users uncomfortable and that objects in very close proximity during movement can also cause discomfort.[8] Meta's developer guidance explains that the vestibular system responds to changes in motion but not to constant velocity, so steady movement is often comfortable, and it advises keeping accelerations brief and infrequent.[10] Crytek also found that responses varied between people: "What works for one may not work for another."[8]
Solutions
Crytek wrote that the method was "super fun, especially when you apply a visual aid".[1] Two aids that Crytek often used in combination with movement to reduce sickness were a "Constraint Screen", which blurs the user's peripheral vision, and a cockpit. Crytek wrote that both can help developers use movements that "might otherwise seem to 'break the rules'".[1] Meta's current design guidance describes the same two approaches: vignettes (tunneling) that darken or occlude the screen edges during movement to limit visible optic flow, and static geometry such as vehicle cabins, cockpits or headgear that obscures part of the environment.[10]
Related research
Crytek's prototype was a game-design experiment, not a controlled study. Researchers have separately evaluated interfaces that also drive travel from head tilt or leaning. Their implementations differ from Crytek's, so their results do not directly measure HMD Position Acceleration.
At CHI 2017, Sam Tregillus, Majed Al Zayer and Eelke Folmer evaluated head tilt, implemented with inertial sensing, as a way to allow hands-free omnidirectional navigation on mobile VR platforms. They noted that walking-in-place only moves users in the direction of their gaze. In a study with 24 subjects on an obstacle-avoidance task, they compared head tilt alone (TILT), a hybrid that used head tilt for direction and walking in place for speed (WIP-TILT), and controller input. TILT was significantly faster than WIP-TILT and joystick input, WIP-TILT and TILT gave the highest presence, and there was no difference in cybersickness between the input methods.[4]
Abraham Hashemian, Bernhard Riecke and colleagues at Simon Fraser University developed HeadJoystick, a seated leaning interface in which the user moves their head toward the target direction, like the handle of a joystick, to control virtual translation velocity, while rotating a swivel chair to turn with a 1:1 mapping.[11][12] In two studies of flying through a sequence of tunnels, HeadJoystick improved accuracy, precision, ease of learning, usability, presence, immersion and the sensation of self-motion (vection) compared with handheld interfaces.[11] A follow-up with three studies (24, 18 and 18 participants) on ground-based reach-the-target, follow-the-path and racing tasks found better performance and higher user ratings than with a touchpad or thumbstick controller, along with reduced motion sickness and task load.[13]
Other comparisons have favored teleportation. Fabio Buttussi and Luca Chittaro compared joystick movement, teleportation and continuous leaning for in-place locomotion with 75 users. Teleportation had the best performance, caused less nausea and received a higher usability score, while leaning outperformed the joystick. They found no significant differences in presence.[5]
See also
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 Julius Carter (2017-09-08). "Developer Perspectives: VR Locomotion - Movement and combinations". CRYENGINE. Crytek. https://www.cryengine.com/news/view/developer-perspectives-vr-locomotion-movement-and-combinations. Retrieved 2026-09-27.
- ↑ 2.0 2.1 Julius Carter (2017-08-23). "Developer Perspectives: VR Locomotion - Movement and Combinations". Meta Horizon OS Developers blog. Meta. https://developers.meta.com/horizon/blog/developer-perspectives-vr-locomotionmovement-and-combinations/. Retrieved 2026-09-27.
- ↑ 3.0 3.1 3.2 "HMD Position Acceleration". YouTube. Meta VR. https://www.youtube.com/watch?v=cG2HSoVZDRI. Retrieved 2026-09-27.
- ↑ 4.0 4.1 Sam Tregillus, Majed Al Zayer, Eelke Folmer (2017). "Handsfree Omnidirectional VR Navigation using Head Tilt". Proceedings of the 2017 CHI Conference on Human Factors in Computing Systems, pp. 4063-4068. ACM. doi:10.1145/3025453.3025521. https://doi.org/10.1145/3025453.3025521. Retrieved 2026-09-27.
- ↑ 5.0 5.1 Fabio Buttussi, Luca Chittaro (2021). "Locomotion in Place in Virtual Reality: A Comparative Evaluation of Joystick, Teleport, and Leaning". IEEE Transactions on Visualization and Computer Graphics, vol. 27, no. 1, pp. 125-136. IEEE. doi:10.1109/TVCG.2019.2928304. https://doi.org/10.1109/TVCG.2019.2928304. Retrieved 2026-09-27.
- ↑ 6.0 6.1 6.2 Ben Lang (2017-08-25). "Oculus and Crytek Explore New & Novel Methods of VR Locomotion". Road to VR. https://www.roadtovr.com/oculus-crytek-explore-new-novel-methods-vr-locomotion/. Retrieved 2026-09-27.
- ↑ Julius Carter (2017-05-11). "Developer Perspectives: VR Locomotion - A Series of Experiments From Crytek". Meta Horizon OS Developers blog. Meta. https://developers.meta.com/horizon/blog/developer-perspectives-vr-locomotion-a-series-of-experiments-from-crytek/. Retrieved 2026-09-27.
- ↑ 8.0 8.1 8.2 8.3 8.4 Julius Carter (2017-05-12). "VR locomotion - A series of experiments from Crytek". CRYENGINE. Crytek. https://www.cryengine.com/news/view/vr-locomotion-a-series-of-experiments-from-crytek. Retrieved 2026-09-27.
- ↑ Dominic Brennan (2017-05-23). "Oculus Teams With Crytek to Share VR Locomotion Experiments". Road to VR. https://www.roadtovr.com/oculus-teams-crytek-share-vr-locomotion-experiments/. Retrieved 2026-09-27.
- ↑ 10.0 10.1 "Locomotion comfort and usability". Meta Horizon OS Developers. Meta. https://developers.meta.com/horizon/design/locomotion-comfort-usability/. Retrieved 2026-09-27.
- ↑ 11.0 11.1 Abraham M. Hashemian, Matin Lotfaliei, Ashu Adhikari, Ernst Kruijff, Bernhard E. Riecke (2022). "HeadJoystick: Improving Flying in VR Using a Novel Leaning-Based Interface". IEEE Transactions on Visualization and Computer Graphics, vol. 28, no. 4, pp. 1792-1809. IEEE. doi:10.1109/TVCG.2020.3025084. https://doi.org/10.1109/TVCG.2020.3025084. Retrieved 2026-09-27.
- ↑ "Leaning-based interfaces improve ground-based VR locomotion". iSpace Research Lab, Simon Fraser University. http://ispace.iat.sfu.ca/project/headjoystick2d/. Retrieved 2026-09-27.
- ↑ Abraham M. Hashemian, Ashu Adhikari, Ernst Kruijff, Markus von der Heyde, Bernhard E. Riecke (2023). "Leaning-Based Interfaces Improve Ground-Based VR Locomotion in Reach-the-Target, Follow-the-Path, and Racing Tasks". IEEE Transactions on Visualization and Computer Graphics, vol. 29, no. 3, pp. 1748-1768. IEEE. doi:10.1109/TVCG.2021.3131422. https://doi.org/10.1109/TVCG.2021.3131422. Retrieved 2026-09-27.