Facilitating the Exploration of Linearly Aligned Objects in Controller-Free 3D Environment with Gaze and Microgestures

As Extended Reality (XR) environments increasingly involve large amounts of data and content, designing effective exploration techniques has become critical. Depth-based object exploration is a common but underexplored task in XR environments, especially in settings without physical devices. Prior studies have largely focused on horizontal or planar interactions, leaving depthoriented exploration relatively overlooked. To bridge this gap, we propose three linearly aligned layer transition techniques (Continuous Push, Push&Return, and Tilt&Return) specifically designed to support efficient, precise, and continuous object exploration along the depth axis within depth-based UIs. In a user study with 30 participants, we compared their performance, usability, and user preference across two different layer configurations (8-layer vs. 16-layer). The results highlight that Continuous Push enables faster exploration with lower effort, while Push&Return provides the highest accuracy and is most preferred by users. Based on these findings, we discuss design implications for depth-based interaction techniques in controller-free XR environments.