Jing Jing Fang

Automatic body feature extraction from a marker-less scanned human body

In this paper, we propose a novel method of body feature extraction from a marker-less scanned body. The descriptions of human body features mostly defined in ASTM (1999) and ISO (1989) are interpreted into logical mathematical definitions. Using these significant definitions, we employ image processing and computational geometry techniques to identify, automatically, body features from the torso cloud points. We have currently extracted 21 feature points and 35 feature lines on the human torso; this number may be extended if necessary. Moreover, less than 2 min processing time is taken for body feature extraction starting from the raw point cloud. This algorithm is successfully tested on several Asian female adults who are aged from 18 to 60.

Factors affecting user performance in haptic assembly

Current computer-aided assembly systems provide engineers with a variety of spatial snapping and alignment techniques for interactively defining the positions and attachments of components. With the advent of haptics and its integration into virtual assembly systems, users now have the potential advantage of tactile information. This paper reports research that aims to quantify how the provision of haptic feedback in an assembly system can affect user performance. To investigate human–computer interaction processes in assembly modeling, performance of a peg-in-hole manipulation was studied to determine the extent to which haptics and stereovision may impact on task completion time. The results support two important conclusions: first, it is apparent that small (i.e. visually insignificant) assembly features (e.g. chamfers) affect the overall task completion at times only when haptic feedback is provided; and second, that the difference is approximately similar to the values reported for equivalent real world peg-in-hole assembly tasks.

Mandibular Defect Reconstruction with the Help of Mirror Imaging Coupled with Laser Stereolithographic Modeling Technique

With the advent of microsurgery, composite defect in the mandible can be repaired with various forms of osteocutaneous free flaps. However, it is difficult to accurately reconstruct a large defect in the mandible when not enough mandibular reference blueprints remain. This case report describes a large ameloblastoma at the left lower molar region and ascending ramus of the mandible in a 53-year-old male patient. Before surgery, spiral computed tomography scanning of the whole skull of the patient was performed. Using three-dimensional reconstruction and mirror imaging coupled with laser stereolithographic technique, a complete mandibular biomodel with idealized shape was fabricated. A titanium reconstruction plate was made using the biomodel as a guide. The tumor mass together with the left mandible from the second premolar to the condylar head area was resected en bloc. The large mandibular defect was then reconstructed with the precontoured titanium plate and three segments of vascularized fibular bone graft fixed along the plate. The temporomandibular joint was restored with temporal is muscle as an interpositional disc replacement. The complex defect in the mandible was thus repaired with satisfactory functioning and esthetic result. We suggest that with the help of mirror imaging coupled with laser stereolithographic technique, a precontoured titanium plate can be made for the reconstruction of large mandibular defects.

3D apparel creation based on computer mannequin model. Part II: Implementations

Purpose – A significant garment restyling tool was developed to perform garment design in three dimensions. It provides the professional designers the abilities of 3D garment creation, restyling, omni‐angle visualization, and fitting evaluation on a digital mannequin model. According to the body tape‐measurements defined in ISO 8559:1999(E) and ASTM D5219‐99 (1999), the extracted feature lines on computer mannequin dominate the shape of the apparel and also its associated fitting results. In this paper, the garment creation by the provided interfaces and its outcomes based on the developed system kernel and its formulas described in part I of the paper is demonstrated.Design/methodology/approach – In part II of this paper, a three‐dimensional garment creation and restyling software based on the kernel infrastructure and formulas is implemented.Findings – Currently, three fundamental dresses, two basic collars, and sleeve are successfully implemented in the creation of free style mannequin‐made apparels. F...

Effects of virtual reality training on functional reaching movements in people with Parkinson’s disease: a randomized controlled pilot trial

Objective: To investigate whether practising reaching for virtual moving targets would improve motor performance in people with Parkinson’s disease. Design: Randomized pretest–posttest control group design. Setting: A virtual reality laboratory in a university setting. Participants: Thirty-three adults with Parkinson’s disease. Interventions: The virtual reality training required 60 trials of reaching for fast-moving virtual balls with the dominant hand. The control group had 60 practice trials turning pegs with their non-dominant hand. Main outcome measures: Pretest and posttest required reaching with the dominant hand to grasp real stationary balls and balls moving at different speeds down a ramp. Success rates and kinematic data (movement time, peak velocity and percentage of movement time for acceleration phase) from pretest and posttest were recorded to determine the immediate transfer effects. Results: Compared with the control group, the virtual reality training group became faster (F = 9.08, P = 0.005) and more forceful (F = 9.36, P = 0.005) when reaching for real stationary balls. However, there was no significant difference in success rate or movement kinematics between the two groups when reaching for real moving balls. Conclusion: A short virtual reality training programme improved the movement speed of discrete aiming tasks when participants reached for real stationary objects. However, the transfer effect was minimal when reaching for real moving objects.

Expert-based customized pattern-making automation: Part I. Basic patterns

Purpose – This paper aims to present a flattening method for developing 2D basic patterns from 3D designed garments. The method incorporates the techniques of professional pattern development for the purpose of pattern‐making automation. The aims of the flattening method are to improve the dressing suitability and to produce pleasing figures by reversing design procedures.Design/methodology/approach – A flattening method is presented in this paper for developing 3D undevelopable NURBS surfaces in 2D. The automatic operation embeds the expertise of pattern makers by reducing total area differences between the designed garments in 3D styles and the two‐dimensional patterns. Basic pattern‐making invokes the boundary constraints which apply mesh alignments techniques.Findings – The global area difference between the original 3D designs and the 2D‐developed pattern is controlled within 5 percent in order to reach the final outcomes of basic patterns, whose shapes are similar to the drawing patterns currently u...

Comparison of Virtual Reality Versus Physical Reality on Movement Characteristics of Persons With Parkinson's Disease: Effects of Moving Targets

OBJECTIVE To compare the performance of reaching for stationary and moving targets in virtual reality (VR) and physical reality in persons with Parkinsons disease (PD). DESIGN A repeated-measures design in which all participants reached in physical reality and VR under 5 conditions: 1 stationary ball condition and 4 conditions with the ball moving at different speeds. SETTING University research laboratory. PARTICIPANTS Persons with idiopathic PD (n=29) and age-matched controls (n=25). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Success rates and kinematics of arm movement (movement time, amplitude of peak velocity, and percentage of movement time for acceleration phase). RESULTS In both VR and physical reality, the PD group had longer movement time (P<.001) and lower peak velocity (P<.001) than the controls when reaching for stationary balls. When moving targets were provided, the PD group improved more than the controls did in movement time (P<.001) and peak velocity (P<.001), and reached a performance level similar to that of the controls. Except for the fastest moving ball condition (0.5-s target viewing time), which elicited worse performance in VR than in physical reality, most cueing conditions in VR elicited performance generally similar to those in physical reality. CONCLUSIONS Although slower than the controls when reaching for stationary balls, persons with PD increased movement speed in response to fast moving balls in both VR and physical reality. This suggests that with an appropriate choice of cueing speed, VR is a promising tool for providing visual motion stimuli to improve movement speed in persons with PD. More research on the long-term effect of this type of VR training program is needed.

Modelling of mandibular movement

In this paper, the authors presented a novel method to reconstruct individual mandible movement in three dimensions by a virtual articulator system. The system provides a synchronized 3D mandibular movement that faithfully reappear ones natural occlusion movements--sagittal border, lateral, and open-close movements. Movement trajectories are approximated by cubic or high-degree curves modelling. During the whole process, X-ray exposure on human is avoided. The authors apply the optimal methodology to approach the collected samples of movements in order to generate specific occlusion curves and surfaces. The system provides a novel method of mimicking occlusion of individuals. It is a useful tool for recording dynamic movements of an individual in both pre- and post-surgery and also for predicting surgical outcomes.

Increasing speed to improve arm movement and standing postural control in Parkinson's disease patients when catching virtual moving balls.

Research has shown that moving targets help Parkinsons disease (PD) patients improve their arm movement while sitting. We examined whether increasing the speed of a moving ball would also improve standing postural control in PD patients during a virtual reality (VR) ball-catching task. Twenty-one PD patients and 21 controls bilaterally reached to catch slow-moving and then fast-moving virtual balls while standing. A projection-based VR system connected to a motion-tracking system and a force platform was used. Dependent measures included the kinematics of arm movement (movement time, peak velocity), duration of anticipatory postural adjustments (APA), and center of pressure (COP) movement (movement time, maximum amplitude, and average velocity). When catching a fast ball, both PD and control groups made arm movements with shorter movement time and higher peak velocity, longer APA, as well as COP movements with shorter movement time and smaller amplitude than when catching a slow ball. The change in performance from slow- to fast-ball conditions was not different between the PD and control groups. The results suggest that raising the speed of virtual moving targets should increase the speed of arm and COP movements for PD patients. Therapists, however, should also be aware that a fast virtual moving target causes the patient to confine the COP excursion to a smaller amplitude. Future research should examine the effect of other task parameters (e.g., target distance, direction) on COP movement and examine the long-term effect of VR training.

Expert‐based customized pattern‐making automation: Part II. Dart design

Purpose – Based on the knowledge of professional pattern makers, this paper aims to propose an expert‐based automation technique of darts generation by aligning and drawing close meshes in basic pattern in Part I. Single dart development, such as waist‐fitting dart, shoulder dart, armscye dart, side dart, and their select combination are also presented.Design/methodology/approach – In this paper, 3D garment surface is first approximated by a finite number of meshes. Patterns are developed by aligning and rotating of the flattened meshes under the constraint of overlay avoidance. The envelop areas between the developed patterns and the curved surface are dramatically reduced from 5 percent of basic pattern to below 3 percent after darts development.Findings – The development patterns are varied in their association with the subjects body figures and the designed garment. Darts in a different location can reduce the total area difference between the flattening undevelopable surface and the original curved ...