User-Empowered Head Movement Techniques in Virtual Reality (VR)

Cover image: Head Rotation Amplification

As part of my Master's thesis in Human-Computer Interaction (HCI) at Umeå University, supervised by Prof. Anders Lundström, I explored novel head rotation amplification techniques in Virtual Reality (VR) specifically designed to overcome the challenges posed by physically restricted turning angles in seated VR environments. The project focused on exploring novel head rotation techniques enhancing user comfort, efficiency, and overall interaction experience.

In seated VR, physical rotation is limited, making full 360° exploration difficult. Amplifying head movements increases the virtual rotation relative to physical movement, enabling users to explore virtual environments with less physical effort.

Implemented Prototype in Unity 3D

Techniques Developed

Constant Gain (Baseline)

Constant amplification: Physical head rotation multiplied by a fixed factor. For example, a 30° turn becomes 60° in VR (gain = 2).

User‑Empowered (Manual) Gain

Manual amplification: Users manually toggle between high and 1:1 normal mapping using VR controllers during ballistic (rapid rotation) and corrective phases for higher accuracy.

Automatic Gain

Dynamic adaptive amplification: Automatic gain adjustment based on head rotation velocity and acceleration to smoothly transition between high gain during ballistic movements and normal gain during precise alignment.

User Study

A rigorous evaluation involving over 30 participants provided both qualitative and quantitative insights into the effectiveness of each method.

Metrics Collected

Task Completion Time: Time required to complete tasks.
Error Rate: The number of times targets were missed, and the angular deviation from the intended target.
Accumulated Offset: The overall angular difference between the task's starting and ending positions within the virtual environment.
Physical vs. Virtual Accumulated head Movement: Accumulated angular head movements were measured in both the physical and virtual environments.
NASA-TLX: User workload assessment.
Cybersickness in Virtual Reality Questionnaire (CSQ-VR): Used to assess the level of motion sickness experienced in virtual reality across different techniques.

Usability Questions Regarding

Comfort and Usability: User comfort levels and intuitive interaction.
Control and Precision: User comfort levels and the ease of interaction during tasks.
Naturalness and Applicability: How naturally the techniques felt and how applicable users found them for VR use.

Qualitative User Feedback

User feedback was gathered through semi-structured interviews to explore the following areas:

How users experienced amplified head rotation compared to normal 1:1 mapping.
How head rotation amplification affected users' sense of direction and spatial orientation.
Preferences between different amplification techniques (manual vs. automatic).
The impact of head rotation amplification on users' sense of immersion in the virtual environment.

The interviews included questions about users' overall experience with each technique, perceived control and speed, ease of targeting, feelings of discomfort or motion sickness, and preferences for manual versus automatic amplification. Participants were also asked about their perception of space and immersion while using amplified head rotation.

The qualitative data was analyzed using thematic analysis, which allowed me to identify key patterns and insights regarding user experiences and preferences related to head rotation amplification in VR.

Tasks

Head Rotation Amplification, 180° Rotation Task — 180° Rotation Task

Head Rotation Amplification, Small Bubbles Task (90° and 180° Conditions) — Small Bubbles Task (90° and 180° Conditions)

Resources & Further Reading