GVU Technical Report Series

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GVU Technical Report Series

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Now showing 1 - 10 of 78

Edgebreaker: A Simple Compression for Surfaces with Handles

(Georgia Institute of Technology, 2002) Rossignac, Jarek ; Lopes, Helio ; Safanova, Alla ; Tavares, Geovan ; Szymczak, Andrzej

The Edgebreaker is an efficient scheme for compressing triangulated surfaces. A surprisingly simple implementation of Edgebreaker has been proposed for surfaces homeomorphic to a sphere. It uses the Corner-Table data structure, which represents the connectivity of a triangulated surface by two tables of integers, and encodes them with less than 2 bits per triangle. We extend this simple formulation to deal with triangulated surfaces with handles and present the detailed pseudocode for the encoding and decoding algorithms (which take one page each). We justify the validity of the proposed approach using the mathematical formulation of the Handlebody theory for surfaces, which explains the topological changes that occur when two boundary edges of a portion of a surface are identified.
Technology Trends Favor Thick Clients for User-Carried Wireless Devices

(Georgia Institute of Technology, 2002) Starner, Thad

A thin client approach to mobile computing pushes as many services as possible on a remote server. However, as will be shown, technology trends indicate that an easy route to improving thin client functionality is to ``thicken'' the client through addition of disk storage, CPU, and RAM. Thus, thin clients will rapidly become multi-purpose thick clients. With time, users may come to consider their mobile system as their primary general-purpose computing device, with their most used files maintained on the mobile system and with desktop systems used primarily for larger displays, keyboards, and other non-mobile interfaces.
Speech and Gesture Multimodal Control of a Whole Earth 3D Visualization Environment

(Georgia Institute of Technology, 2002) Krum, David Michael ; Omoteso, Olugbenga ; Ribarsky, William ; Starner, Thad ; Hodges, Larry F.

A growing body of research shows several advantages to multimodal interfaces including increased expressiveness, exibility, and user freedom. This paper investigates the design of such an interface that integrates speech and hand gestures. The interface has the additional property of operating relative to the user and can be used while the user is in motion or stands at a distance from the computer display. The paper then describes an implementation of the multimodal interface for a whole earth 3D visualization environment which presents navigation interface challenges due to the large magnitude of scale and extended spaces that is available. The characteristics of the multimodal interface are examined, such as speed, recognizability of gestures, ease and accuracy of use, and learnability under likely conditions of use. This implementation shows that such a multimodal interface can be effective in a real environment and sets some parameters for the design and use of such interfaces.
A Computer Music Implementation Course Using Active Essays

(Georgia Institute of Technology, 2002) Guzdial, Mark ; Greenlee, Jim

Computer music tends to be the domain of musicians, electrical engineers, mathematicians, and physicists. Today, only CSI-level knowledge is necessary to do a serious review and exploration of computer music, as the algorithms have become more well understood (and thus easier to explain), and Moore's Law makes even inefficient algorithms successful. A serious impediment, however, has been the lack of a text that is written from a programming perspective (instead of mathematical or musical). By using active essays in Squeak, a set of notes have been created where students can read the code, execute it, hear the result, see the waveform, and take the Fourier transform.
What's Happening?: Promoting Community Awareness through Opportunistic, Peripheral Interfaces

(Georgia Institute of Technology, 2002) Zhao, Qiang Alex ; Stasko, John T.

Maintaining an awareness of information about one's own community and its members is viewed as being important, but is becoming more challenging today as people are overwhelmed by so many different forms of information. We have developed the "What's Happening" suite of tools to help convey relevant and interesting community information to people in a manner that is minimally distracting and disruptive, with little or no user set-up and interaction. The tools are more lightweight than e-mail and Usenet news, and opportunistic in providing information to people when they are not deeply focused on some other task. This paper describes these tools and the techniques that they use, as well as our observations of their utility and impact.
Interactive Walls: Addressing the Challenges of Large-scale Interactive Surfaces

(Georgia Institute of Technology, 2002) Summet, Jay W. ; Somani, Ramswaroop ; Abowd, Gregory D. ; Rehg, James M.

We present a prototype large-scale interactive electronic whiteboard wall. Various input, output and vision technologies are used to create a surface that can capture digital ink as well as support pen-based interaction with displayed information on subregions of the wall. A simple automated capture application is demonstrated on our prototype surface and research challenges for developing more complex applications with this interactive technology are discussed.
From Urban Terrain Models to Visible Cities

(Georgia Institute of Technology, 2002) Ribarsky, William ; Wasilewski, Anthony A. ; Faust, Nick L. (Nickolas Lea)

We are now faced with the possibility and in some cases the results of acquiring accurate digital representations of our cities. But these cities will not be capable of interactive visualization unless we meet some fundamental challenges. The first challenge is to take data from multiple sources, which are often accurate in themselves but incomplete, and weave them together into comprehensive models. Because of the size and extent of the data that can now be obtained, this modeling task is daunting and must be accomplished in a semi-automated manner. Once we have comprehensive models, and especially if we can build them rapidly and extend them at will, the next question is what to do with them. Thus the second challenge is to make the models visible. In particular they must be made interactively visible so they can be explored, inspected, and analyzed. In this article, we discuss the nature of the acquired urban data and how we are beginning to meet the challenges and produce visually navigable models. These models provide the basis for building virtual environments for a variety of applications.
Choreography Driven Characters

(Georgia Institute of Technology, 2002) Sternberg, Daniel ; Essa, Irfan

High-level control of an articulated humanoid character for animation is much desired by animators. Current options of key-framing, motion capture and simulation either give too much or too little control to the animator in dealing with general motions. The main reason for this lack of action level, higher form of control is that low-level representations, mostly driven by data or samples are used by current systems. Though high-level representations of motion do exist, it is difficult to incorporate them into systems for animation. To facilitate this, we first introduce a representation based on dance notation. We then introduce a second notation based on L-systems. We show how the latter representation falls in the middle of the range of notations, allowing us to rotate, encode, and synthesize various movements. We then show the applicability of these representations by presenting animations created by an input of dance notation.
Semi-Automated Landscape Feature Extraction and Modeling

(Georgia Institute of Technology, 2002) Wasilewski, Anthony A. ; Faust, Nick L. (Nickolas Lea) ; Grimes, Matthew ; Ribarsky, William

We have developed a semi-automated procedure for generating correctly located 3D tree objects from overhead imagery. Cross-platform software partitions arbitrarily large, geocorrected and geolocated imagery into manageable sub-images. The user manually selects tree areas from one or more of these sub-images. Samples are taken from these areas, and color statistics are computed. Tree areas are detected in subsequent images. Tree group blobs are then narrowed to lines using a special thinning algorithm which retains the topology of the blobs, and also stores the thickness of the parent blob. Maxima along these thinned tree groups are found, and used as individual tree locations within the tree group. Magnitudes of the local maxima are used to scale the radii of the tree objects. Grossly overlapping trees are culled based on a comparison of tree-tree distance to combined radii. Tree color is randomly selected based on the distribution of sample tree pixels, and height is estimated from tree radius. The final tree objects (perpendicular intersecting tree cutouts) are then inserted into a terrain database which can be navigated by VGIS 1 , a high-resolution global terrain visualization system developed at Georgia Tech.
Organization and Simplification of High-Resolution 3D City Facades

(Georgia Institute of Technology, 2002) Parry, Robert Mitchell ; Ribarsky, William ; Shaw, Christopher D. ; Jang, Justin ; Faust, Nick L. (Nickolas Lea)

This paper describes an approach for the organization and simplification of high-resolution geometry and imagery data for 3D buildings for interactive city navigation. At the highest level of organization, building data are inserted into a global hierarchy that supports the large-scale storage of cities around the world. This structure also provides fast access to the data suitable for interactive visualization. At this level the structure and simplification algorithms deal with city blocks. An associated latitude and longitude coordinate for each block is used to place it in the hierarchy. Each block is decomposed into building facades. A facade is a texture-mapped polygonal mesh representing one side of a city block. Therefore, a block typically contains four facades, but it may contain more. The facades are partitioned into relatively flat surfaces called faces. A texture-mapped polygonal mesh represents the building facades. By simplifying the faces first instead of the facades, the dominant characteristics of the building geometry are maintained. At the lowest level of detail, each face is simplified into a single texture-mapped polygon. An algorithm is presented for the simplification transition between the high- and low-detail representations of the faces. Other techniques for the simplification of entire blocks and even cities are discussed.