Eye tracking: Difference between revisions

*'''[[Calibration]]:''' A per-user calibration process is usually required upon first use, and sometimes periodically, to account for individual differences in eye physiology (e.g., corneal shape, pupil size range) and the precise fit of the headset. This typically involves the user looking at specific points displayed within the headset.

**'''Gaze Selection/Pointing''': Allows users to select objects, menu items, or targets simply by looking at them. This is often combined with a confirmation action like a button press on a [[controller (computing)|controller]], a [[hand tracking]] gesture (e.g., pinch), or a short dwell time.<ref name="Piumsomboon2017">Piumsomboon, T., Lee, G., Lindeman, R. W., & Billinghurst, M. (2017). Exploring natural eye-gaze-based interaction for immersive virtual reality. *IEEE Symposium on 3D User Interfaces*, 36-39.</ref>

**'''Intent Prediction''': Systems can anticipate user actions or needs based on gaze patterns (e.g., highlighting an object the user looks at intently).

**'''Training and Simulation Analysis''': Assessing trainee attention, situational awareness, and decision-making processes in professional simulations (e.g., medical, aviation).

*'''[[Accessibility]]''': Eye tracking offers a powerful hands-free input modality for users with limited physical mobility, enabling them to navigate interfaces, communicate (e.g., gaze typing), and control applications within VR/AR.

*'''[[HTC VIVE Pro Eye]]''': An earlier enterprise-focused headset integrating Tobii eye tracking (accuracy ~0.5-1.1 degrees, 120Hz). Newer VIVE models may offer eye tracking via add-ons (e.g., VIVE Focus 3 Eye Tracker).<ref name="ViveProEye">HTC Corporation. (n.d.). *VIVE Pro Eye*. VIVE. Retrieved November 16, 2023, from https://www.vive.com/us/product/vive-pro-eye/overview/</ref>

*'''Latency''': The time delay between an actual eye movement and when it is detected and reported by the system. Crucial for real-time applications like foveated rendering and interaction, ideally below 20ms, though system latency can sometimes be higher (e.g., 45-81 ms reported in some studies).<ref name="SpringerReview2022">Mack, S., et al. (2022). A survey on eye tracking in virtual and augmented reality. *Virtual Reality*, 27, 1597–1625. https://link.springer.com/article/10.1007/s10055-022-00738-z</ref>

*'''Robustness / Tracking Ratio''': The percentage of time the system successfully tracks the eyes under various conditions (e.g., different users, lighting, eyewear).

*'''Calibration Drift''': Accuracy can degrade over time due to headset slippage or physiological changes, potentially requiring recalibration. Some studies note significant drift (e.g., 30% accuracy loss) within minutes under certain conditions.<ref name="SpringerReview2022"/>

*'''Individual Variations''': Differences in eye physiology (e.g., corneal curvature, pupil size, eyelid shape, ethnicity-related features, "droopy" eyelids) can impact tracking accuracy and robustness.

*'''[[Privacy]] Implications''': Eye tracking data is highly sensitive [[biometric data]]. It can potentially reveal information about identity, attention focus, cognitive state, emotional responses, interests, and even certain health conditions (e.g., fatigue, intoxication, neurological disorders), raising significant privacy concerns if collected, stored, or shared improperly.<ref name="Kroger2020">Kröger, J. L., Lutz, O. H. M., & Müller, F. (2020). What does your gaze reveal about you? On the privacy implications of eye tracking. *Privacy and Identity Management*, 226-241.</ref><ref name="EFFPrivacyVRAR">Crockford, K., & Electronic Frontier Foundation. (2020, November 19). *The Privacy Bird Isn't Real: Your VR/AR Data Is*. Electronic Frontier Foundation. https://www.eff.org/deeplinks/2020/11/privacy-bird-isnt-real-your-vrar-data</ref>

*'''Compatibility with Eye Conditions''': Certain ophthalmological conditions (e.g., strabismus, nystagmus, ptosis, corneal scarring) can significantly impair or prevent accurate eye tracking for affected individuals.

*'''Sensor Fusion''': Combining eye tracking data with other sensor inputs (e.g., [[electroencephalography]] (EEG), head tracking, facial expression tracking) for richer interaction and analysis.

*'''[[Unity (game engine)|Unity]]''': Provides APIs through its XR Interaction Toolkit and potential vendor-specific SDKs (e.g., Tobii XR SDK).

*'''[[Khronos Group]] / [[OpenXR]]''': Defines standard APIs for accessing eye tracking data (e.g., [[XR_EXT_eye_gaze_interaction]]).