Virtual Reality Modeling Language File Research Articles

Image Fusion in Craniofacial Virtual Reality Modeling Based on CT and 3dMD Photogrammetry

The aim of this study was to demonstrate the feasibility of building a craniofacial virtual reality model by image fusion of 3-dimensional (3D) CT models and 3 dMD stereophotogrammetric facial surface. A CT scan and stereophotography were performed. The 3D CT models were reconstructed by Materialise Mimics software, and the stereophotogrammetric facial surface was reconstructed by 3 dMD patient software. All 3D CT models were exported as Stereo Lithography file format, and the 3 dMD model was exported as Virtual Reality Modeling Language file format. Image registration and fusion were performed in Mimics software. Genetic algorithm was used for precise image fusion alignment with minimum error. The 3D CT models and the 3 dMD stereophotogrammetric facial surface were finally merged into a single file and displayed using Deep Exploration software. Errors between the CT soft tissue model and 3 dMD facial surface were also analyzed. Virtual model based on CT-3 dMD image fusion clearly showed the photorealistic face and bone structures. Image registration errors in virtual face are mainly located in bilateral cheeks and eyeballs, and the errors are more than 1.5 mm. However, the image fusion of whole point cloud sets of CT and 3 dMD is acceptable with a minimum error that is less than 1 mm. The ease of use and high reliability of CT-3 dMD image fusion allows the 3D virtual head to be an accurate, realistic, and widespread tool, and has a great benefit to virtual face model.

Three-dimensional rotational angiography guidance for aneurysm surgery

The aim of this study was to investigate the feasibility of integrating three-dimensional rotational angiography (3D-RA) data into a surgical navigation system and to assess its accuracy and potential clinical benefit. The study cohort consisted of 16 patients with 16 intracranial aneurysms who had been scheduled for routine or emergency surgery. Rotational angiography data were exported using a virtual reality modeling language file format and imported into the BrainLAB VectorVision2 image-guided surgery equipment. During 3D-RA the position of the head was measured using a special headframe. The authors also determined the accuracy of 3D-RA image guidance and the clinical benefit as judged by the surgeon, including, for example, early identification of branching vessels and the aneurysm. There was good correspondence between the 3D-RA-based navigation data and the intraoperative vascular anatomy in all cases, with a maximum error of 9 degrees of angulation and 9 degrees of rotation. In eight cases, the surgeon determined that the 3D-RA image guidance facilitated the surgical procedure by predicting the location of the aneurysm or the origin of a branching artery that had been covered by brain tissue and blood clots. The integration of 3D-RA into surgical navigation systems is feasible, but it currently requires a new perspective-registration technique. The intraoperative 3D view provides useful information about the vascular anatomy and may improve the quality of aneurysm surgery in selected cases.

MAVL and StickWRLD: visually exploring relationships in nucleic acid sequence alignments

Many powerful tools have been created to detect and describe the similarities between nucleic acid or protein sequences. Frequently these take the form of a sequence consensus, expressing simple most popular positional identities, positional identities with allowances for varying positions or some type of statistical description of the positional frequency characteristics of the defining sequence family. Despite the fact that some provide intuitively interpretable descriptions of the consensuses themselves, they typically do not give the viewer any information about regions of the sequence that might have inter-positional dependencies, and that therefore do not obey a strict consensus behavior. Herein, we present MAVL (Multiple Alignment Variation Linker) and StickWRLD. MAVL is our web-based application for detecting and displaying both positive and negative inter-positional correlations in nucleic acid sequences. MAVL examines all positional pairs in each of a collection of pre-aligned sequences and determines any pairs that occur with either greater or lesser frequency than a positional frequency matrix would predict. These data are then composited into a StickWRLD representation and supplied back to the user as a VRML (virtual reality modeling language) file. MAVL and StickWRLD can be accessed at http://www.microbial-pathogenesis.org/stickwrld/. A tutorial that explains MAVL features and demonstrates typical user interactions with StickWRLD graphs is available at http://www.microbial-pathogenesis.org/stickwrld/tutorial/sticktut2.html. This tutorial is quite large; please be patient while it loads.

Development of 3D graphics and VRML libraries for Web3D platform by using Java

AbstractThis paper proposes a new 3D graphics programming environment for Web3D on the Internet. To develop 3D graphics programs on the Internet is not easy because there is no popular 3D graphics library like OpenGL. For this purpose, we developed a 3D graphics library called jGL by using Java exclusively. jGL is a general‐purpose 3D graphics library, and its API (Application Programming Interface) is defined in a manner quite similar to that of OpenGL. Since jGL offers the same functionalities as OpenGL, programmers can use it easily. Furthermore, since people have recently been able to use simple Java programs on cellular phones, migration experimentation toward i‐αppli is also described in this paper. Moreover, VRML (Virtual Reality Modeling Language) is a standard file format for describing 3D models on the Internet. To display a 3D model on the Internet, people may like to use the VRML file format. Therefore, we also developed a VRML library called jVL by using Java exclusively as an extension of jGL. In this paper, the results and some detailed descriptions are updated compared with those in Ref. 3. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(10): 47–55, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10393

Scene Graph For Dynamic Virtual Environment: Spangraph

The VRML (Virtual Reality Modeling Language) file format is a popular file format for describing a graphical scene: object shapes, appearance properties, animation, and interactions. However, the format does not provide any mechanism for describing the order of objects' appearances or their changes over time. Instead, an interface to Java is offered for controlling the temporal relationships between objects in the scene. The use of Java makes it difficult for a person with his programming skill to author a dynamic virtual environment. In this paper we attach a span and an age to each object and their hierarchical and temporal relations are expressed in a new data structure, called a span graph (SpanGraph). An object in the span graph, when alive, grows its age and performs associated actions according to its age during the extent of the time span. Furthermore, the object may have child objects whose spans are sub-extents of the parent span. In this paper, we demonstrate uses of the SpanGraph in virtual studio and virtual engineering design applications.

Geometry coding and VRML

The virtual-reality modeling language (VRML) is rapidly becoming the standard file format for transmitting three-dimensional (3-D) virtual worlds across the Internet. Static and dynamic descriptions of 3-D objects, multimedia content, and a variety of hyperlinks can be represented in VRML files. Both VRML browsers and authoring tools for the creations of VRML files are widely available for several different platforms. In this paper, we describe the topologically assisted geometric compression technology included in our proposal for the VRML compressed binary format. This technology produces significant reduction of file sizes and, subsequently, of the time required for transmission of such filed across the Internet. Compression ratios of 50:1 or more are achieved for large models. The proposal also includes a binary encoding to create compact, rapidly parsable binary VRML files. The proposal is currently being evaluated by the Compressed Binary Format Working Group of the VRML consortium as a possible extension of the VRML standard. In the topologically assisted compression scheme, a polyhedron is represented using two interlocking trees: a spanning tree of vertices and a spanning tree of triangles. The connectivity information represented in other compact schemes, such as triangular strips and generalized triangular meshes, can be directly derived from this representation. Connectivity information for large models is compressed with storage requirements approaching one bit per triangle. A variable-length, optionally lossy compression technique is used for vertex positions, normals, colors, and texture coordinates. The format supports all VRML property binding conventions.

Web based 3-D medical image visualization on the PC.

With the recent advance of Web and its associated technologies, information sharing on distribute computing environments has gained a great amount of attention from many researchers in many application areas, such as medicine, engineering, and business. One basic requirement of distributed medical consultation systems is that geographically dispersed, disparate participants are allowed to exchange information readily with each other. Such software also needs to be supported on a broad range of computer platforms to increase the softwares accessibility. In this paper, the development of world-wide-web based medical consultation system for radiology imaging is addressed to provide platform independence and greater accessibility. The system supports sharing of 3-dimensional objects. We use VRML (Virtual Reality Modeling Language), which is the defacto standard in 3-D modeling on the Web. 3-D objects are reconstructed from CT or MRI volume data using a VRML format, which can be viewed and manipulated easily in Web-browsers with a VRML plug-in. A Marching cubes method is used in the transformation of scanned volume data sets to polygonal surfaces of VRML. A decimation algorithm is adopted to reduce the number of meshes in the resulting VRML file. 3-D volume data are often very large in size, hence loading the data on PC level computers requires a significant reduction of the size of the data, while minimizing the loss of the original shape information. This is also important to decrease network delays. A prototype system has been implemented (http://cybernet5.snu.ac.kr/-cyber/mrivrml .html), and several sessions of experiments are carried out.

VRML adds a new dimension to Web browsing

One of the most exciting developments on the World Wide Web is the emergence of the Virtual Reality Modeling Language (VRML). While true cyberspace is quite a few years in the future, VRML (often pronounced 'vermal') does offer some tantalizing previews of what is to come. VRML is away of compactly describing 3D objects and scenes, based on Silicon Graphics' Open Inventor file format. It lets authors embed links in and apply textures to objects. Authors can also set the levels of detail displayed to approximate real life, where objects in the distance seem less detailed than closer objects. VRML files can be smaller than fully rendered worlds because the format merely specifies what the client machine should render. In other words, your machine receives the VRML instructions, then renders the scene itself. The speed of your machine's graphics capabilities can sometimes have as much influence as the speed of your Internet connection on how long you wait to view files. The type of computer you have will also affect the quality of the graphics.