Series
GVU Technical Report Series

Series Type
Publication Series
Description
Associated Organization(s)
Associated Organization(s)
Organizational Unit

Publication Search Results

Now showing 1 - 10 of 45
  • Item
    Punctuated Simplification of Man-Made Objects
    (Georgia Institute of Technology, 2005) Jang, Justin ; Wonka, Peter ; Ribarsky, William ; Shaw, Christopher D.
    We present a simplification algorithm for manifold polygonal meshes of plane-dominant models. Models of this type are likely to appear in man-made environments. While traditional simplification algorithms focus on generality and smooth meshes, the approach presented here considers a specific class of man-made models. By detecting and classifying edge loops on the mesh and providing a guided series of binary mesh partitions, our approach generates a series of simplified models, each of which better respects the semantics of these kinds of models than conventional approaches do. A guiding principle is to eliminate simplifications that do not make sense in constructed environments. This, coupled with the concept of punctuated simplifica-tion, leads to an approach that is both efficient and delivers high visual quality. Comparative results are given.
  • Item
    Precision Markup Modeling and Display in a Global Geospatial Environment
    (Georgia Institute of Technology, 2003) Wartell, Zachary Justin ; Ribarsky, William ; Faust, Nick L. (Nickolas Lea)
    A data organization, scalable structure, and multiresolution visualization approach is described for precision markup modeling in a global geospatial environment. The global environment supports interactive visual navigation from global overviews to details on the ground at the resolution of inches or less. This is a difference in scale of 10 orders of magnitude or more. To efficiently handle details over this range of scales while providing accurate placement of objects, a set of nested coordinate systems is used, which always refers, through a series of transformations, to the fundamental world coordinate system (with its origin at the center of the earth). This coordinate structure supports multi-resolution models of imagery, terrain, vector data, buildings, moving objects, and other geospatial data. Thus objects that are static or moving on the terrain can be displayed without inaccurate positioning or jumping due to coordinate round-off. Examples of high resolution images, 3D objects, and terrain-following annotations are shown.
  • Item
    Appearance-Preserving View-Dependent Visualization
    (Georgia Institute of Technology, 2003) Jang, Justin ; Ribarsky, William ; Shaw, Christopher D. ; Wonka, Peter
    In this paper, a new quadric-based view-dependent simplification scheme is presented. The scheme provides a method to connect mesh simplification controlled by a quadric error metric with a level-of-detail hierarchy that is accessed continuously and efficiently based on current view parameters. A variety of methods for determining the screen-space metric for the view calculation are implemented and evaluated, including an appearance-preserving method that has both geometry- and texture- preserving aspects. Results are presented and compared for a variety of models.
  • Item
    Rendering Vector Data Over Global, Multi-resolution 3D Terrain
    (Georgia Institute of Technology, 2003) Wartell, Zachary Justin ; Kang, Eunjung ; Wasilewski, Anthony A. ; Ribarsky, William ; Faust, Nick L. (Nickolas Lea)
    Modern desktop PCs are capable of taking 2D Geographic Information System (GIS) applications into the realm of interactive 3D virtual worlds. In prior work we developed and presented graphics algorithms and data management methods for interactive viewing of a 3D global terrain system for desktop and virtual reality systems. In this paper we present a key data structure and associated render-time algorithm for the combined display of multi-resolution 3D terrain and traditional GIS polyline vector data. Such vector data is traditionally used for representing geographic entities such as political borders, roads, rivers and cadastral information.
  • Item
    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.
  • Item
    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.
  • Item
    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.
  • Item
    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.
  • Item
    Visual Query of Time-Dependent 3D Weather in a Global Geospatial Environment
    (Georgia Institute of Technology, 2002) Ribarsky, William ; Faust, Nick L. (Nickolas Lea) ; Wartell, Zachary Justin ; Shaw, Christopher D. ; Jang, Justin
    A multi-key data organization is developed for handling a continuous stream of large scale, time-dependent, 3D weather data in a global environment. The structure supports inserting the data in real-time as they arrive or retrieving weather events at desired times and locations from archived weather histories. In either case data are organized for interactive visualization and visual query.
  • Item
    Evaluation of a Multimodal Interface for 3D Terrain Visualization
    (Georgia Institute of Technology, 2002) Krum, David Michael ; Omoteso, Olugbenga ; Ribarsky, William ; Starner, Thad ; Hodges, Larry F.
    This paper describes an evaluation of various interfaces for visual navigation of a whole Earth 3D terrain model. A mouse driven interface, a speech interface, a gesture interface, and a multimodal speech and gesture interface were used to navigate to targets placed at various points on the Earth. Novel speech and/or gesture interfaces are candidates for use in future mobile or ubiquitous applications. This study measured each participant's recall of target identity, order, and location as a measure of cognitive load. Timing information as well as a variety of subjective measures including discomfort and user preferences were taken. While the familiar and mature mouse interface scored best by most measures, the speech interface also performed well. The gesture and multimodal interface suffered from weaknesses in the gesture modality. Weaknesses in the speech and multimodal modalities are identifed and areas for improvement are discussed.