The limitations of current AR assembly training systems’ guided information have prompted exploration into enhancing efficiency and user experience. By integrating information decay strategies with individual learning status, this paper focuses on customizing decay to improve AR training. Against the backdrop of AR manual assembly training, we designed a user-centered adaptive gradual decay training program (“Adapt Grad Dec”) and developed a corresponding AR system using Unity 3D. To evaluate the effectiveness of “Adapt Grad Dec” in AR manual assembly training, a user study was conducted that compared it against both pre-programmed decay conditions and a non-decay condition, drawing on insights from previous research. The pre-programmed decay conditions included three variations: (1) only gradual decay of training information (“Only Grad Dec”), (2) fast decay of training information with manual adjustment options (“Fst Dec and Manl Adj”), and (3) gradual decay with manual adjustment options (“Grad Dec and Manl Adj”). In contrast, the un-decay condition involved no reduction of training information throughout the process (“UnDec”). Results demonstrated that participants performed better in various aspects under the “Adapt Grad Dec” condition compared to “Only Grad Dec.” Based on findings, we propose that combining individual learning conditions with gradual decay strategies is a potentially effective approach to enhancing AR training outcomes. Additionally, the study also discusses limitations and future research directions.

Current Virtual Reality (VR) sketching systems lack natural bimanual interactions for drawing curves on 3D models. This article introduces HoldTabSketch, a VR sketching system that uses a tracked graphics tablet as a touch-sensitive physical proxy to enable realistic bimanual interactions for 3D curve drawing. The system features a Reoriented Bounding Boxes (ROBB) haptic redirection technique that automatically aligns virtual pen and hand movements with various virtual objects while maintaining tactile feedback. The system supports two additional bimanual interaction modes: 1) bare-hand object manipulation with pen-based sketching using visual feedback, and 2) tablet-assisted tangible interactions combining grasp support and surface drawing. A 12-user comparative study showed the tablet-based physical proxy significantly improved the realism of 3D object manipulation and surface drawing, yielding higher user preference and usability compared to vision-only or basic tangible approaches. The system demonstrates how hybrid physical-digital proxies can enhance 3D creative workflows in VR.

Augmented reality (AR) can bring a new interactive experience to the collaboration between users. When users are in the same place, there are two modes of joint operation for the same object: parallel-work (PW) and cross-work (CW). PW means two users perform their tasks, while CW means assisting each other. To investigate the difference that collaboration using PW and CW in an AR environment brings to users, we developed a two-person local collaboration system, LoCol. We designed and conducted user experiments by selecting the tasks of adjusting the virtual model of the assembly and adding missing boundaries in the model. The results showed that CW led to a higher sense of social coexistence while reducing workload. In terms of task completion time and accuracy, CW and PW each had advantages. We found that users generally want to reduce unnecessary repetitive operations and frequent movement by working with others. This is likely an important criterion for determining who is better suited for a particular job in either approach.

The projection-augmented reality assembly assistance system, which supports natural multi-modal human–computer interaction, has the potential to improve interaction efficiency. However, the effectiveness of the interaction method is compromised by the interference caused by the dynamically changing industrial environment. To address this issue, this study proposed a multi-model interaction model based on fuzzy theory and developed an environment perception decision-making interaction system. This system continuously monitors real-time environment data, evaluates interaction performance, and visually recommends the optimal method to assist users in completing their tasks. A comparative experiment was conducted between the proposed system and a non-environment perception interaction system. The collected data, including interaction success rate, task time, system usability, and user experience, were analyzed. The results demonstrated that the proposed system effectively enhances the adaptability and comfort of computer systems in complex environments and improves communication efficiency between humans and machines.

Consistent visual and haptic feedback is an important way to improve the user experience when interacting with virtual objects. However, the perception provided in Augmented Reality (AR) mainly comes from visual cues and amorphous tactile feedback. This work explores how to simulate positional vibrotactile feedback (PVF) with multiple vibration motors when colliding with virtual objects in AR. By attaching spatially distributed vibration motors on a physical haptic proxy, users can obtain an augmented collision experience with positional vibration sensations from the contact point with virtual objects. We first developed a prototype system and conducted a user study to optimize the design parameters. Then we investigated the effect of PVF on user performance and experience in a virtual and real object alignment task in the AR environment. We found that this approach could significantly reduce the alignment offset between virtual and physical objects with tolerable task completion time increments. With the PVF cue, participants obtained a more comprehensive perception of the offset direction, more useful information, and a more authentic AR experience.

We propose Fluid3DGuides, a drawing guide technique to help users draw structured sketches more accurately in VR. The prototype system continuously infers visual guide lines for the user based on the user’s instant stroke drawing intention and its potential constraint relationship with the existing strokes. We evaluated our prototype through a pilot user study with six participants by comparing the proposed guide technique against the non-guide drawing condition. Participants gave positive comments on ease of use and drawing accuracy. They found that the technique could reduce the time and effort required to find the corrected drawing perspective and obtain more accurate 3D structured sketches.

Haptic guidance is an essential research topic of haptic interaction technology. In some conditions, haptic guidance devices could be better at assisting navigation. We developed Haptic Compass, a prototype with active vibrotactile feedback by attaching vibration motors to a cylinder-shaped physical object, to provide directional cues for haptic guidance. To validate the prototype, we conducted two user studies. The first study investigated if users could identify the vibrotactile feedback from the prototype. The results showed that participants could effectively recognize and judge the vibration direction. In the second study, we evaluated the task completion time and the movement error among the Visual-only, Haptic-Only and Haptic-Visual feedback conditions in a typical path-guiding task. We found that, together with visual feedback, haptic feedback could enhance task performance and user experience for direct path guidance. Performance of the two studies demonstrated that our prototype has the potential to be an alternative for applications where non-wearable haptic feedback is desired.

This paper investigates how two different unique gaze visualizations (the head pointer(HP), eye gaze(EG)) affect table-size physical tasks in Mixed Reality (MR) remote collaboration. We developed a remote collaborative MR Platform which supports sharing of the remote expert's HP and EG. The prototype was evaluated with a user study comparing two conditions: sharing HP and EG with respect to their effectiveness in the performance and quality of cooperation. There was a statistically significant difference between two conditions on the performance time, and HP is a good proxy for EG in remote collaboration.

Haptic feedback has shown its great value in HCI research and applications for enhancing user experiences. Simulating people's tactile sensations of virtual objects is currently a primary research target. Different from wearing motors on fingers or hands, we attached vibration motors on a physical object to simulate the augmented sense of collision with virtual objects to bare hands. We developed a novel sensor-based proof-of-concept prototype that distributes multiple vibration motors around a physical object and provides vibrational sensations from the collision direction through combinations of motors. Users can obtain augmented haptic feedback when manipulating the augmented physical object to interact with virtual objects in an AR environment. We first studied the influence of the number and input voltage of motors for a correct judgment of different directions to identify the design parameters of the prototype. Then we investigated the effect of introducing the prototype in a typical manipulation task in AR. We found the prototype was efficient for enhancing human performance and collision experience with virtual objects together with visual feedback.

This paper presents a method that groups multiple over traced pen strokes for converting online multiple over tracing sketches into line drawings. Firstly, tolerance zones around strokes are built during stroke preprocessing. Secondly, users inputs are divided into stroke groups by a grouping procedure, which relies on a over tracing judgment algorithom that uses the percentage of the sampling points of the smaller stroke which fall into the other's tolerance zone to determine whether two strokes should be grouped together. Finally, the stroke groups are fitted with 2D geometric primitives including lines, ellipses and arcs. The proposed method is proved to be robust and achieves a satisfactory interpretative efficiency.

Three-dimensional (3D) body scanning technology opens opportunities for virtual try-on and automatic made-to-measure apparel design. This paper proposes a new feature-based parametric method for modeling human body shape from scanned point clouds of a 3D body scanner [TC]2. The human body model consists of two layers: the skeleton and the cross sections of each body part. First, a simple skeleton model from the body scanner [TC]2system has been improved by adding and adjusting the position of joints in order to better address some fit issues related to body shape changes such as spinal bending. Second, an automatic approach to extracting semantic features for cross sections has been developed based on the body hierarchy. For each cross section, it is described by a set of key points which can be fit with a closed cardinal spline. According to the point distribution in point clouds, an extraction method of key points on cross sections has been studied and developed. Third, this paper presents an interpolation approach to fitting the key points on a cross section to a cardinal spline, in which different tension parameters are tested and optimized to represent simple deformations of body shape. Finally, a connection approach of body parts is proposed by sharing a boundary curve. The proposed method has been tested with the developed virtual human model (VHM) system which is robust and easier to use. The model can also be imported in a CAD environment for other applications.