VRMosaic: Web access from within a virtual environment

For the foreseeable future, users of virtual reality systems will likely spend more time in the “real” environment than in a virtual environment. In the “real” environment, users access much of their data using flat screen applications, which include tools such as authoring and analysis programs and even hyperlinked browsers. We believe that users will find VEs more appealing if they can import their flat screen applications. We also believe that the World Wide Web infrastructure, and supporting tools such as NCSA Mosaic, Netscape's Navigator, and Sun's HotJava, have become a de facto standard both for making data available and allowing limited interaction with that data. These beliefs motivated us to develop a technology for porting flat screen applications based on the 3.1 version of the InterViews toolkit into VR. NCSA Mosaic provided us with a real application that would: (1) test our infrastructure effectively; and (2) provide a compelling application example. We used our “2D interface in VR” infrastructure to port Mosaic into RealEyes, our VR system. Dubbed “VRMosaic”, this application lets users familiar with Mosaic access the Web from within an immersive VE. But VRMosaic is not just an embedded version of NCSA Mosaic-it also allows for VR specific features such as navigation within the VE     

Scene graphs in the new millennium

Hardware 3D graphics accelerators will be ubiquitous in the new millennium. The great majority of 3D graphics programs will, almost exclusively, use scene graphs. Rarely will graphics programs use immediate mode-if at all-and then only for very special effects, and scene graphs will grow to support new modalities such as sound and haptics. Outrageous? Probably. Predicting the future is never easy. By looking at where we are today and analyzing technology trends, these predictions may seem even more outrageous, outrageously mundane. The author considers how graphics technologies, hardware and software, are evolving at exponential rates     

Efficient collision detection using bounding volume hierarchies ofk-DOPs

Collision detection is of paramount importance for many applications in computer graphics and visualization. Typically, the input to a collision detection algorithm is a large number of geometric objects comprising an environment, together with a set of objects moving within the environment. In addition to determining accurately the contacts that occur between pairs of objects, one needs also to do so at real-time rates. Applications such as haptic force feedback can require over 1000 collision queries per second. We develop and analyze a method, based on bounding-volume hierarchies, for efficient collision detection for objects moving within highly complex environments. Our choice of bounding volume is to use a discrete orientation polytope (k-DOP), a convex polytope whose facets are determined by halfspaces whose outward normals come from a small fixed set of k orientations. We compare a variety of methods for constructing hierarchies (BV-trees) of bounding k-DOPs. Further, we propose algorithms for maintaining an effective BV-tree of k-DOPs for moving objects, as they rotate, and for performing fast collision detection using BV-trees of the moving objects and of the environment. Our algorithms have been implemented and tested. We provide experimental evidence showing that our approach yields substantially faster collision detection than previous methods     

The Java 3D API and virtual reality

Java programmers can quickly and easily define graphics programs using Java 3D's scene graph classes. An expanded view model lets applications seamlessly operate in a variety of single- and multiple-display, nonhead-tracked and head-tracked, display environments. This view model relies on the flexible InputDevice interface that Java 3D provides to remove most of the vagaries of hardware trackers     

Effect of dietary α-linolenic acid on n−3 fatty acids of rainbow trout lipids

The effects of α-linolenic acid enriched diets on the lipid composition of rainbow trout (Oncorhynchus mykiss) muscle and liver were determined. Diets containing 0, 4, 10 or 20% (wt/wt) linseed oil were fed to 280 trout for up to 64 days. Linolenic acid levels in total lipid, neutral lipid and phospholipid of liver and muscle increased with duration of intake. The linolenic acid content of total lipid in muscle increased from 10 mg to 355 mg/100 g flesh. There was no significant increase in the elongated desaturated products, i.e., eicosapentaenoic or docosahexaenoic acids, in either tissue during the feeding period.