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Temporal continuity of visual attention for future gaze prediction in immersive virtual reality


Available Online:2020-02-28

Abstract (62) | PDF (9) | HTML (41)
Eye tracking technology is receiving increased attention in the field of virtual reality. Specifically, future gaze prediction is crucial in pre-computation for many applications such as gaze-contingent rendering, advertisement placement, and content-based design. To explore future gaze prediction, it is necessary to analyze the temporal continuity of visual attention in immersive virtual reality.
In this paper, the concept of temporal continuity of visual attention is presented. Subsequently, an autocorrelation function method is proposed to evaluate the temporal continuity. Thereafter, the temporal continuity is analyzed in both free-viewing and task-oriented conditions.
Specifically, in free-viewing conditions, the analysis of a free-viewing gaze dataset indicates that the temporal continuity performs well only within a short time interval. A task-oriented game scene condition was created and conducted to collect users’ gaze data. An analysis of the collected gaze data finds the temporal continuity has a similar performance with that of the free-viewing conditions. Temporal continuity can be applied to future gaze prediction and if it is good, users’ current gaze positions can be directly utilized to predict their gaze positions in the future.
The current gaze’s future prediction performances are further evaluated in both free-viewing and task-oriented conditions and discover that the current gaze can be efficiently applied to the task of short-term future gaze prediction. The task of long-term gaze prediction still remains to be explored.
Personalized cardiovascular intervention simulation system


Available Online:2020-01-18

Abstract (115) | PDF (16) | HTML (83)
This study proposes a series of geometry and physics modeling methods for personalized cardiovascular intervention procedures, which can be applied to a virtual endovascular simulator.
Based on personalized clinical computed tomography angiography (CTA) data, mesh models of the cardiovascular system were constructed semi-automatically. By coupling 4D magnetic resonance imaging (MRI) sequences corresponding to a complete cardiac cycle with related physics models, a hybrid kinetic model of the cardiovascular system was built to drive kinematics and dynamics simulation. On that basis, the surgical procedures related to intervention instruments were simulated using specially-designed physics models. These models can be solved in real-time; therefore, the complex interactions between blood vessels and instruments can be well simulated. Additionally, X-ray imaging simulation algorithms and realistic rendering algorithms for virtual intervention scenes are also proposed. In particular, instrument tracking hardware with haptic feedback was developed to serve as the interaction interface of real instruments and the virtual intervention system. Finally, a personalized cardiovascular intervention simulation system was developed by integrating the techniques mentioned above.
This system supported instant modeling and simulation of personalized clinical data and significantly improved the visual and haptic immersions of vascular intervention simulation.
It can be used in teaching basic cardiology and effectively satisfying the demands of intervention training, personalized intervention planning, and rehearsing.
Two-phase real-time rendering method for realistic water refraction


Available Online:2019-12-26

Abstract (185) | PDF (20) | HTML (108)
Realistic rendering has been an important goal of several interactive applications, which requires an efficient virtual simulation of many special effects that are common in the real world. However, refraction is often ignored in these applications. Rendering the refraction effect is extremely complicated and time-consuming.
In this study, a simple, efficient, and fast rendering technique of water refraction effects is proposed. This technique comprises a broad and narrow phase. In the broad phase, the water surface is considered flat. The vertices of underwater meshes are transformed based on Snell’s Law. In the narrow phase, the effects of waves on the water surface are examined. Every pixel on the water surface mesh is collected by a screen-space method with an extra rendering pass. The broad phase redirects most pixels that need to be recalculated in the narrow phase to the pixels in the rendering buffer.
We analyzed the performances of three different conventional methods and ours in rendering refraction effects for the same scenes. The proposed method obtains higher frame rate and physical accuracy comparing with other methods. It is used in several game scene, and realistic water refraction effects can be generated efficiently.
The two-phase water refraction method produces a tradeoff between efficiency and quality. It is easy to implementin modern game engines, and thus improve the quality of rendering scenes in video games or other real-time applications.