10888216
Hypertexturing complex volume objects
This paper will examine hypertexture rendering techniques and will demonstrate how volume data sets may be adapted in order for hypertexture to be applied. Details are given of a process for the conversion of complex objects, such as CT scans, into accurate distance fields. Hypertexture is applied to these objects and example renderings include the UNC CThead, a chess piece, a dodecahedron and a tank. Additional information is given about soft objects, density modulation functions, ray marching and controlling hypertexture application.
22331464
Vector-City Vector Distance Transform
This paper will examine the current chamfer and vector distance transforms for encoding objects as distance fields. A new vector distance transform is introduced which uses the city-block chamfer distance transform as a basis. Detailed error analysis using real CT data is presented, demonstrating the improved accuracy of the new approach over existing methods. The production of a subvoxel accurate distance field is also demonstrated by employing an improved classification. Distance fields are shown for skull and chess piece datasets.
9085764
Distance Field Compression
This paper compares various techniques for compressing floating point distance fields. Both lossless and lossy techniques are compared against a new lossless technique. The new Vector Transform technique creates a predictor based upon a Vector Distance Transform and its suitability for distance field data sets is reported. The new technique produces a lossless encoding at a third of the file size of entropy encoders, and equivalent to lossy wavelet transforms, where around 75% of the coefficients have been set to zero. The algorithm predicts each voxel value linearly based upon two previous voxels chosen from one of 13 directions which have been previously computed. Those that cannot be predicted are explicitly stored.
9893455
Interactive Modelling in Decision Support Systems
Abstract In the past, the use of computer models in decision support has involved the interpretation of written reports derived from the output of the model. In recent years, however, the development of micro-computers and istributed computing systems has made it possible for decision-makers to be provided, not with a written report, but with a copy of the model itself. The new relationship between the user and the model, which this development establishes, has important implications for the way in which decision support systems (DSSs) are designed and used.
1577279
Using keyphrases as search result surrogates on small screen devices
This paper investigates user interpretation of search result displays on small screen devices. Such devices present interesting design challenges given their limited display capabilities, particularly in relation to screen size. Our aim is to provide users with succinct yet useful representations of search results that allow rapid and accurate decisions to be made about the utility of result documents, yet minimize user actions (such as scrolling), the use of device resources, and the volume of data to be downloaded. Our hypothesis is that keyphrases that are automatically extracted from documents can support this aim. We report on a user study that compared how accurately users categorized result documents on small screens when the document surrogates consisted of either keyphrases only, or document titles. We found no significant performance differences between the two conditions. In addition to these encouraging results, keyphrases have the benefit that they can be extracted and presented when no other document metadata can be identified.
42586645
The music is the message
the music being played by her tiny mobile audio appliance. She's standing waiting for a train. Other commuters swarm nearby, headphones on, listening in more muted ways to the soundtracks they've chosen to accompany today's episode of their daily routine. Mobile music players—iPods, Walkmans and the like—are exciting for those of us involved in thinking about the future of mobile devices and services. Like the mobile phone—increasing numbers of which also sport a music player—these are gadgets that people actually desire, and aspire to own. They have vast storage capacities, increasingly sophisticated processors and pleasing, effective mechanisms for users to control their func-tionality. From click and jog wheels to high-resolution color displays, these players are far from being the impoverished devices that typified mobile platforms just a few years ago. And there are hundreds of millions of them in circulation—Apple sold five million in the first quarter of 2006 alone. But at the same time, these marvelous mobiles could be seen as an obstacle to the bright futures dreamt up in the research labs. How will people be able to make use of the ubiquitous computing infrastructure being envisaged, the anytime, everywhere access to information and services, when they are immersed in digital sound bubbles of their own choosing? Some mobile listeners, at first sight, certainly appear cut off. Another scene: A young man stares out of a train window, watching the long green fields flash by. His eyes are bright but still; his gaze betrays a mood of deep reflection. Listening to music on expensive , noise-reducing headphones, what is he thinking? Is he sadly contemplating a lover left or anticipating a longed-for meeting at his destination? How can we design mobile services that will fit this context? The conventional clumsy beeps, vibrations, and attention-seeking displays seem out of place. What opportunities are there to build more emphatic systems , systems to enhance the music and environmental experience or to provide ways for the listener to later reflect on the situations they've lived through in relation to the music they've heard? At other times, though, these sound bubbles seem more permeable, don't they? One of the photos of people listening to music available on a popular image-sharing site is entitled " Listening to Kim's iPod and talking to Joe! " A teenager holds a mobile phone to her left ear while wearing the distinctive white music-player headphones. Chatting and …
14178775
A Parallel Algorithm for Mesh Smoothing
Maintaining good mesh quality during the generation and refinement of unstructured meshes in finite-element applications is an important aspect in obtaining accurate discretizations and well-conditioned linear systems. In this article, we present a mesh-smoothing algorithm based on nonsmooth optimization techniques and a scalable implementation of this algorithm. We prove that the parallel algorithm has a provably fast runtime bound and executes correctly for a parallel random access machine (PRAM) computational model. We extend the PRAM algorithm to distributed memory computers and report results for two- and three-dimensional simplicial meshes that demonstrate the efficiency and scalability of this approach for a number of different test cases. We also examine the effect of different architectures on the parallel algorithm and present results for the IBM SP supercomputer and an ATM-connected network of SPARC Ultras.
19544571
Too close for comfort? Distance and engagement in interpretive information systems research
In this paper, we seek to explore the implications of the assumptions underlying interpretivism for the preferred relationship between the researcher and the research phenomenon. The growing interest in interpretive information systems research has drawn attention to the need to gain access to the interpretations of social actors. Various data-gathering methods are available to the researcher to achieve such access. These may be seen as located on a spectrum in terms of the degree of engagement between the researcher and the research subject. While engagement is not without its drawbacks from a research perspective, it may be argued that it enables good access to the sorts of data that interpretive researchers are seeking. Most of the research reported in the information systems (IS) field, however, has adopted relatively distant methods by which the researcher avoids intervention in the research context. Some of the characteristics of more engaged forms of research are illustrated through a discussion of a participant observation study of executive information systems development. This research has highlighted a number of issues that can be seen to be common to other data-gathering methods. Reasons for the neglect of engaged data-gathering methods are explored, and it is suggested that consideration of the issues it raises may contribute to more reflexive interpretive IS research practice.