Effortless manipulation informs and relies on preshaping: the subconscious posing of the hand before grasping. Virtual environments and the design of interaction techniques alters interaction requirements like contact and reach, forcing behavioural adaptation. We present a comparative study investigating preshaping behaviour across direct versus indirect (gaze-assisted) and bare-hand versus controller techniques on a docking task. Results reveal that response patterns scale with anticipated task difficulty, and that direct techniques elicit effective posing of the hand. Indirect techniques shortcut hand transport and, in turn lacks the sensory feedback to guide planning, inducing efficient but attenuated responses that necessitate compensatory manipulation and clutching. Notably, controllers that afford in-hand rotation allow users to extend their range of motion. These findings can inform interaction design to better afford preshaping and optimise 3D manipulation tasks.

Hand-tracking based 3D object manipulation in Extended Reality (XR) typically employs a pinch gesture for acquisition and manipulation through a direct mapping from 6-degrees-of-freedom (DOF) hand movement to that of the object. In this work, we investigate the effect of separating this mapping to concurrent 3DOF controls (DOF-Separation) of translation and rotation of the virtual object using the position and orientation of the hand independently. We aim to understand how DOF-Separation could ease manipulation for different techniques with varying requirements for hand position and orientation during acquisition, including Virtual Hand, Hand Ray, and Gaze&Pinch. Through a user study that features a docking task in VR, we found that DOF-Separation significantly improves the manipulation performance of Hand Ray, while improving that of Virtual Hand only in difficult tasks of combined translation and rotation. We suggest future XR systems to adopt DOF-Separation for input in manipulation-heavy applications, such as 3D design.

In 3D user interfaces, reaching out to grab and manipulate something works great until it is out of reach. Indirect techniques like gaze and pinch offer an alternative for distant interaction, but do not provide the same immediacy or proprioceptive feedback as direct gestures. To support direct gestures for faraway objects, we introduce SightWarp, an interaction technique that exploits eye-hand coordination to seamlessly summon object proxies to the user's fingertips. The idea is that after looking at a distant object, users either shift their gaze to the hand or move their hand into view-triggering the creation of a scaled near-space proxy of the object and its surrounding context. The proxy remains active until the eye-hand pattern is released. The key benefit is that users always have an option to immediately operate on the distant object through a natural, direct hand gesture. Through a user study of a 3D object docking task, we show that users can easily employ SightWarp, and that subsequent direct manipulation improves performance over gaze and pinch. Application examples illustrate its utility for 6DOF manipulation, overview-and-detail navigation, and world-in-miniature interaction. Our work contributes to expressive and flexible object interactions across near and far spaces.

Extended Reality (XR) systems with hand-tracking support direct manipulation of objects with both hands. A common interaction in this context is for the non-dominant hand (NDH) to orient an object for input by the dominant hand (DH). We explore bimanual interaction with gaze through three new modes of interaction where the input of the NDH, DH, or both hands is indirect based on Gaze+Pinch. These modes enable a new dynamic interplay between our hands, allowing flexible alternation between and pairing of complementary operations. Through applications, we demonstrate several use cases in the context of 3D modelling, where users exploit occlusion-free, low-effort, and fluid two-handed manipulation. To gain a deeper understanding of each mode, we present a user study on an asymmetric rotate-translate task. Most participants preferred indirect input with both hands for lower physical effort, without a penalty on user performance. Otherwise, they preferred modes where the NDH oriented the object directly, supporting preshaping of the hand, which is more challenging with indirect gestures. The insights gained are of relevance for the design of XR interfaces that aim to leverage eye and hand input in tandem.