Browsing by Author "Machuca, Mayra Donaji Barrera"

Now showing 1 - 6 of 6

Citation Count: 0
Effect of Grip Style on Peripersonal Target Pointing in VR Head Mounted Displays
(Ieee Computer Soc, 2023) Batmaz, Anıl Ufuk; Saraç Stroppa, Mine; Sarac, Mine; Machuca, Mayra Donaji Barrera; Stuerzlinger, Wolfgang
When working in Virtual Reality (VR), the user's performance is affected by how the user holds the input device (e.g., controller), typically using either a precision or a power grip. Previous work examined these grip styles for 3D pointing at targets at different depths in peripersonal space and found that participants had a lower error rate with the precision grip but identified no difference in movement speed, throughput, or interaction with target depth. Yet, this previous experiment was potentially affected by tracking differences between devices. This paper reports an experiment that partially replicates and extends the previous study by evaluating the effect of grip style on the 3D selection of nearby targets with the same device. Furthermore, our experiment re-investigates the effect of the vergence-accommodation conflict (VAC) present in current stereo displays on 3D pointing in peripersonal space. Our results show that grip style significantly affects user performance. We hope that our results are useful for researchers and designers when creating virtual environments.
Citation Count: 4
Effect of Stereo Deficiencies on Virtual Distal Pointing
(Assoc Computing Machinery, 2022) Batmaz, Anıl Ufuk; Mughrabi, Moaaz Hudhud; Machuca, Mayra Donaji Barrera; Stuerzlinger, Wolfgang
Previous work has shown that the mismatch between disparity and optical focus cues, i.e., the vergence and accommodation conflict (VAC), affects virtual hand selection in immersive systems. To investigate if the VAC also affects distal pointing with ray casting, we ran a user study with an ISO 9241:411 multidirectional selection task where participants selected 3D targets with three different VAC conditions, no VAC, i.e., targets placed roughly at 75 cm, which matches the focal plane of the VR headset, constant VAC, i.e., at 400 cm from the user, and varying VAC, where the depth distance of targets changed between 75 cm and 400 cm. According to our results, the varying VAC condition requires the most time and decreases the throughput performance of the participants. It also takes longer for users to select targets in the constant VAC condition than without the VAC. Our results show that in distal pointing placing objects at different depth planes has detrimental effect on the user performance.
Citation Count: 9
The Effect of the Vergence-Accommodation Conflict on Virtual Hand Pointing in Immersive Displays
(Assoc Computing Machinery, 2022) Batmaz, Anıl Ufuk; Machuca, Mayra Donaji Barrera; Sun, Junwei; Stuerzlinger, Wolfgang
Previous work hypothesized that for Virtual Reality (VR) and Augmented Reality (AR) displays a mismatch between disparities and optical focus cues, known as the vergence and accommodation conflict (VAC), affects depth perception and thus limits user performance in 3D selection tasks within arm's reach (peri-personal space). To investigate this question, we built a multifocal stereo display, which can eliminate the influence of the VAC for pointing within the investigated distances. In a user study, participants performed a virtual hand 3D selection task with targets arranged laterally or along the line of sight, with and without a change in visual depth, in display conditions with and without the VAC. Our results show that the VAC influences 3D selection performance in common VR and AR stereo displays and that multifocal displays have a positive effect on 3D selection performance with a virtual hand.
Citation Count: 0
Evaluating Voxel-Based Graphical Passwords for Virtual Reality
(Ieee Computer Soc, 2024) Rawat, Prashant; Turkmen, Rumeysa; Nwagu, Chukwuemeka; Sunday, Kissinger; Machuca, Mayra Donaji Barrera
Previous work has proposed using voxel-based graphical passwords (VGPs) for Virtual Reality (VR) as a secure, easy-to-remember way to authenticate users. Moreover, eye-tracking technology adds another level of security, as it avoids observational threats when entering the password. However, previous work has yet to evaluate the user performance, usability, and memorability of different combinations of VGPs. In two user studies, we first identified the best combination of shape and volume for VGPs. Then, we compare 3D versus 2D VGPs. Our results show that a cube is the best shape regarding usability and user preference. We also identified that 2D VGPs are easier to remember than 3D VGPs, as shown by a higher password accuracy and lower error rate. Our results inform the implementation of VGPs and other graphical passwords in VR.
Citation Count: 2
Exploring Discrete Drawing Guides to Assist Users in Accurate Mid-air Sketching in VR
(Assoc Computing Machinery, 2022) Batmaz, Anıl Ufuk; Pfeuffer, Ken; Machuca, Mayra Donaji Barrera; Batmaz, Anil Ufuk; Gellersen, Hans
Even though VR design applications that support sketching are popular, sketching accurately in mid-air is challenging for users. In this paper, we explore discrete visual guides that assist users' stroke accuracy and drawing experience inside the virtual environment. We also present an eye-tracking study that compares continuous, discrete, and no guide in a basic drawing task. Our experiment asks participants to draw a circle and a line using three different guide types, three different sizes and two different orientations. Results indicate that discrete guides are more user-friendly than continuous guides, as the majority of participants preferred their use, while we found no difference in speed/accuracy compared to continuous guides. Potentially, this can be attributed to distinct eye-gaze strategies, as discrete guides led users to shift their eyes more frequently between guide points and the drawing cursor. Our insights are useful for practitioners and researchers in 3D sketching, as they are a first step to inform future design applications of how visual guides inside the virtual environment affect visual behaviour and how eye-gaze can become a tool to assist sketching.
Citation Count: 2
Re-investigating the Effect of the Vergence-Accommodation Conflict on 3D Pointing
(Assoc Computing Machinery, 2023) Batmaz, Anıl Ufuk; Saraç Stroppa, Mine; Sarac, Mine; Machuca, Mayra Donaji Barrera; Stuerzlinger, Wolfgang
The vergence-accommodation conflict (VAC) limits user performance in current Virtual Reality (VR) systems. In this paper, we investigate the effects of the VAC in a single-focal VR system using three experimental conditions: with no VAC, with a constant VAC, and with a varying VAC. Previous work in this area had yielded conflicting results, so we decided to re-investigate this issue. Eighteen participants performed an ISO 9241:411 task in a study that closely replicates previous work, except that the angle of the task space was rotated 20 degrees downward, to make the task less fatiguing to perform, which addresses a potential confound in previous work. We found that the varying VAC condition had worse performance than the other conditions, which indicates that the contrasting results in previous work were very likely due to biomechanical factors. We hope that our work contributes to the understanding of the influence of the VAC in VR systems and potential strategies for improving user experience and performance in immersive virtual environments.