Centre for Vision Research

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Open Access
Augmented Reality Water-Level Task
(2023-08-04) Abadi, Romina; Allison, Robert
The``Water Level Task'' asks participants to draw the water level in a tilted container. Studies showed that many adults have difficulty with the task. Our study aimed to determine if the misconception about water orientation happens in a more natural environment. We implemented an AR water-in-container effect to create an augmented reality (AR) version of the Water-Level task (AR-WLT). In the AR-WLT, participants interacted with two containers half full of water in a Hololens2 AR display and were asked to determine which looked more natural. In at least one of the two simulations, the water surface did not remain horizontal. A traditional online WLT was created to recruit low and high-scoring participants. Our results showed that low-scoring individuals were likelier to make errors in the AR version. However, participants did not choose simulations close to their 2D drawings, suggesting different cognitive and perceptual factors were involved in different environments.
Open Access
Depth Perception Under Scaled Motion Parallax in Virtual Reality
(2023-08-04) Teng. Xue; Allison, Robert
This thesis investigates the impact of mismatch between virtual and physical motion on the perception of object shape. We varied the gain between virtual and physical head motion and measured the effect on depth, distance and shape perception. Our results showed that under monocular viewing, both depth and distance settings decreased with increasing gain, especially at close distances. The average effect sizes of gain were up to -0.061 m/gain unit and -0.40 m/gain unit on depth and distance, respectively, when measured on a standard fold with depth of 1 m. Observers experienced less distortions than predicted from a geometric model and very little depth distortion (not statistically significant effect of gain) under binocular viewing. The distance distortion caused by gain was reduced by up to 56.6% compared to monocular viewing. Binocular cues to depth and distance and large distance (at 6 m) enhance humans’ tolerance to visual and kinesthetic mismatch.
Open Access
Evaluating 3D pointing techniques
Teather, Robert John; Stuerzlinger, Wolfgang; Allison, Robert; MacKenzie, Scott
"This dissertation investigates various issues related to the empirical evaluation of 3D pointing interfaces. In this context, the term ""3D pointing"" is appropriated from analogous 2D pointing literature to refer to 3D point selection tasks, i.e., specifying a target in three-dimensional space. Such pointing interfaces are required for interaction with virtual 3D environments, e.g., in computer games and virtual reality. Researchers have developed and empirically evaluated many such techniques. Yet, several technical issues and human factors complicate evaluation. Moreover, results tend not to be directly comparable between experiments, as these experiments usually use different methodologies and measures. Based on well-established methods for comparing 2D pointing interfaces this dissertation investigates different aspects of 3D pointing. The main objective of this work is to establish methods for the direct and fair comparisons between 2D and 3D pointing interfaces. This dissertation proposes and then validates an experimental paradigm for evaluating 3D interaction techniques that rely on pointing. It also investigates some technical considerations such as latency and device noise. Results show that the mouse outperforms (between 10% and 60%) other 3D input techniques in all tested conditions. Moreover, a monoscopic cursor tends to perform better than a stereo cursor when using stereo display, by as much as 30% for deep targets. Results suggest that common 3D pointing techniques are best modelled by first projecting target parameters (i.e., distance and size) to the screen plane."
Open Access
Factors for Interactive Liquid Perception in Augmented Reality on Mobile Devices
(2019-07-02) Fung, Brandon; Allison, Robert
Augmented reality (AR) is one of the hottest things with Apple and Google trying to capture people's interests and wonder. Given these new needs, there have not been much on what the best thing to do when creating these experiences. Thus in my work, I investigate the best way to bring believable virtual interactive liquids into the real world. Believability is what the user would feel is a more representative of a liquid in real life even when the liquid is virtual. Therefore, I examine three factors for virtual liquids, namely the dynamics and texturing of the liquid and the real world lighting. This works finds that motion models are the most important factor for humans to believe that the virtual fluid in AR is a liquid regardless of angles. This allow developers to focus on the motion models rather than any other factors when creating new experiences in AR.
Open Access
Gaze-Contingent Multi-Modal and Multi-Sensory Applications
(2024-11-07) Vinnikov, Margarita; Allison, Robert
Gaze-contingent displays are applications that are driven by the user's gaze. They are an important tool for many multi-modal and multi-sensory domains. They can be used to precisely control the retinal image in real time to study visual control of natural behaviour through experimentation, or to improve user experience in virtual reality applications. In this dissertation, I explored the application of gaze-contingent display technology to dierent models and senses and evaluate whether such applications can be useful for simulation, psychophysical research and human-computer interaction. Specically, I have looked at the visual gaze-contingent display and an audio gaze-contingent display. I examined the effects of simulated visual defects on user's perception and control of self-motion during locomotion. I found that gaze-contingent display simulations of visual defects signicantly altered visual patterns and impaired the accuracy and precision of judgement of heading. I also examined the impact of simulating gaze-contingent depth-of-field for monocular and stereoscopic displays. The experimental data showed that the alleviation of negative eects associated with stereo displays depends on the user's age and the types of scenes that are viewed. Finally, I simulated gaze-contingent audio displays that imitated the cocktail party effect. My audio enhancement techniques turned to be very benecial for applications that have to deal with user's attention to multiple sources of sounds (speakers) such as teleconferences and social games. Finally, in this dissertation, I demonstrated that gaze-contingent systems can be used in many aspects of virtual system design and if combined together (used for multiple cues and senses) can be a very powerful tool for augmenting and improving the overall user experience.
Open Access
Modelling the Relationship Between Physiological Measures of Motion Sickness
(2023-08-04) Shodipe, Oluwaseyi Elizabeth; Allison, Robert
Car sickness is anticipated to occur more frequently in self-driving vehicles because of their design. This thesis involved an investigation using machine learning techniques with physiological measures to detect and predict the severity of car sickness in real-time every two minutes. A total of 40 adults were exposed to two conditions, each involving a 20-minute ride on a motion-base simulator. Car sickness incidence and severity were subjectively measured using the Fast Motion Sickness (FMS) and Simulator Sickness Questionnaire (SSQ). Car sickness symptom was successfully elicited in 31 participants (77.5%) while avoiding simulator sickness. Results showed that head movement had the strongest relationship with car sickness, and there was a moderate correlation between heart rate and skin conductance. The machine learning models revealed a medium correlation between the physiological measures and the FMS scores. An acceptable classification score distinguishing between motion-sick and non-motion-sick participants was found using the random forest model.
Open Access
Shape Perception of Clear Water in Photo-Realistic Images
(2017-07-27) Sultana, Arhum; Allison, Robert
Light plays a vital role in the perception of transparency, depth and shape of liquids. The perception of the surfaces of liquids is made possible with an understanding of refraction of light and knowledge of the underlying texture geometry. Given this, what specific characteristics of the natural optical environment are essential to the perception of transparent liquids, specifically with respect to efficiency and realism? In this thesis, a light path triangulation method for the recovery of transparent surface shape and a system to estimate the perceived shape of any arbitrary-shaped object with a refractive surface are proposed. A psycho-physical experiment was conducted to investigate this using the perceived shape of water from stereo images using a real time stereoscopic 3-D depth gauge. The results suggest that people are able to consistently perceive shape of liquids from photo-realistic images and that regularity in underlying texture facilitates human judgement of surface shape.
Open Access
Subjective Assessment of Image Compression Artefacts on Stereoscopic Display
(2019-03-05) Mohona, Sanjida Sharmin; Allison, Robert
Image and video quality are important to depict any pictorial information vividly and correctly. With the advancement of technology, we can produce high-quality images and can display those in advanced high-resolution displays. But as high-quality images continue to increase in size, transmitting these exceeds the limited bandwidth of display links. To cope, we need to compress the images but desire that the user cannot perceive any difference between the compressed and uncompressed images. In my thesis, psychophysical experiments with a flicker paradigm were undertaken to do a subjective assessment of the visibility of compression artefacts of two sets of images with two codecs viewed on a stereoscopic display. For one set of images the result shows that artefacts can be silenced in some stereo images relative to 2D while testing with the other set of images was inconclusive. This thesis documented evidence for silencing of artefacts in 3D displays. Other differences between stereoscopic and 2D presentation can be predicted but were not observed here (perhaps due to floor effects). Further large-scale subjective assessment with challenging images may help to get a concrete conclusion.
Open Access
The Effects of Gravity on Self-Motion Perception
(2016-11-25) Guterman, Pearl Shaina; Allison, Robert
Gravity is the most pervasive force that we encounter. For instance, we observe a variety of objects being accelerated toward the Earth by gravity, but we also experience these forces when we are simply stationaryas gravity is a constant accelerationor when we are ourselves in motion, such as when we are locomoting on foot, driving a vehicle, jumping or skiing. It follows that our ability to successfully navigate our environment must somehow take into account the effects of gravity on our body's motion-detecting sensesa dynamic relationship which changes with self-motion and self-orientation. The goal of this dissertation was to investigate how body orientation relative to gravity influences visual-vestibular interactions in visually-induced perception of self-motion (i.e., vection). Specifically, I examined this relationship by placing observers in varied postures and presenting visual displays simulating forward/backward self-motion with vertical/horizontal viewpoint oscillation, that mimics components produced by head-movements in real self-motion. I found that tilting observers reduced vection and the two viewpoint oscillations similarly enhanced vection, suggesting that current postural and oscillation-based vection findings are best explained by ecology. I also examined the influence of scene structure and alignment of the body and visual motion relative to gravity on vection. Observers in different postures viewed simulated translational self-motion displays consisting of either a single rigid structure or dots. The experimental data showed that vection depended on both posture and the perceived interpretation of the visual scene, indicating that self-motion perception is modulated by high-order cognitive processes. I also found that observers reported illusory tilt of the stimulus when they were not upright. I investigated these observer reports of a posture-dependent perceived stimulus tilt by presenting upright and tilted observers with static and motion stimuli that were tilted from the graviational vertical. Postural-dependent tilt effects were found for both these stimuli and were greater for motion experienced as self-motion than external motion. Taken together, the results of this dissertation demonstrate that our perception of self-motion is influenced by gravity, and by prior experiences and internal mental representations of our visual world.
Open Access
The Neural Correlates of Vection: An fMRI Study
(2015-08-28) Kirollos, Ramy; Allison, Robert
Vection is an illusion of visually-induced self-motion in a stationary observer. I used different types of vection stimuli in a functional magnetic resonance imaging (fMRI) study to determine the interaction between cortical visual regions and cortical vestibular regions during vection. My findings suggest that the cingulate sulcus visual area is heavily involved in self-motion processing. The parieto-insular vestibular cortex, showed a significant change in blood oxygenation level dependent signal activity during vection but to a lesser extent than CSv. Behavioural data correlated with the neuroimaging data (in CSv and PIVC) as both show a significant difference when comparing the radial oscillating condition to the radial smooth condition in CSv and PIVC - suggesting a neural correlate of the jitter effect. My results suggest that the brain region of primary importance in the self-motion debate is CSv - a region that has received little attention in the vection literature to date.

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