Virtual Walkthrough System Research Articles

Spectrum-based synthesis of vibrotactile stimuli: active footstep display for crinkle of fragile structures

When a human crinkles or scrunches a fragile object, for which the yield force is very small that it is hardly perceived, they identify the material of the object based on tactile stimuli delivered to the skin. In addition, humans are able to recognize materials even when they are crinkled at different speeds. In order to realize these human recognition features of the crinkle of a fragile object, we develop a vibrotactile synthesis method. This method synthesizes the vibrotactile acceleration stimuli in response to a crinkle speed based on the preliminarily measured acceleration spectra. Using this method, we develop an active footstep display that presents a virtual crinkle of fragile structures made of different materials to its users. Experimental participants could identify three of the four types of virtual structure materials at rates significantly higher than the chance level. The four materials were copy and typing paper, aluminum foil, and polypropylene film. Furthermore, the trends of answer ratios exhibit good correspondence with those for the real cylindrical fragile objects. We conclude that the developed method is valid for the virtual crinkle of fragile structures and will enhance the validity of virtual reality systems, such as a virtual walkthrough system.

Design and Implementation of Campus 3D Virtual Walkthrough System - Take Hunan Science and Technology University as an Example

Along with the rapid development of computer and network technology, the current of digitization has become inevitable trend of global economic development, and digital city has gradually aroused people's attention in recent years. In the application of urban simulation, people can have an immersion omnibearing walkthrough with the method of dynamic interaction in a virtual 3D environment. Without ever leaving home, you can appreciate the scenery of a strange city. This paper has researched key technology of scene simulation on visual reality, and implementd the scene simulation system based on visual environment of Hunan Science and Technology University. With the practice and test, the constructed campus simulation system in the paper has operated smoothly, and users can achieve the visual walkthrough on campus.

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Multiserver support for large-scale distributed virtual environments

CyberWalk is a distributed virtual walkthrough system that we have developed. It allows users at different geographical locations to share information and interact within a shared virtual environment (VE) via a local network or through the Internet. In this paper, we illustrate that as the number of users exploring the VE increases, the server will quickly become the bottleneck. To enable good performance, CyberWalk utilizes multiple servers and employs an adaptive region partitioning technique to dynamically partition the whole VE into regions. All objects within each region will be managed by one server. Under normal circumstances, when a viewer is exploring a region, the server of that region will be responsible for serving all requests from the viewer. When a viewer is crossing the boundary of two or more regions, the servers of all the regions involved will be serving requests from the viewer since the viewer might be able to view objects within all these regions. This is analogous to evaluating a database query using a parallel database server, which could improve the performance of serving a viewer's request tremendously. We evaluate the performance of this multiserver architecture of CyberWalk via a detail simulation model.

Cyberwalk: a web-based distributed virtual walkthrough environment

A distributed virtual walkthrough environment allows users connected to the geometry server to walk through a specific place of interest, without having to travel physically. This place of interest may be a virtual museum, virtual library or virtual university. There are two basic approaches to distribute the virtual environment from the geometry server to the clients, complete replication and on-demand transmission. Although the on-demand transmission approach saves waiting time and optimizes network usage, many technical issues need to be addressed in order for the system to be interactive. CyberWalk is a web-based distributed virtual walkthrough system developed based on the on-demand transmission approach. It achieves the necessary performance with a multiresolution caching mechanism. First, it reduces the model transmission and rendering times by employing a progressive multiresolution modeling technique. Second, it reduces the Internet response time by providing a caching and prefetching mechanism. Third, it allows a client to continue to operate, at least partially, when the Internet is disconnected. The caching mechanism of CyberWalk tries to maintain at least a minimum resolution of the object models in order to provide at least a coarse view of the objects to the viewer. All these features allow CyberWalk to provide sufficient interactivity to the user for virtual walkthrough over the Internet environment. In this paper, we demonstrate the design and implementation of CyberWalk. We investigate the effectiveness of the multiresolution caching mechanism of CyberWalk in supporting virtual walkthrough applications in the Internet environment through numerous experiments, both on the simulation system and on the prototype system.