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Independent Quadtrees

Description: This dissertation deals with the problem of manipulating and storing an image using quadtrees. A quadtree is a tree in which each node has four ordered children or is a leaf. It can be used to represent an image via hierarchical decomposition. The image is broken into four regions. A region can be a solid color (homogeneous) or a mixture of colors (heterogeneous). If a region is heterogeneous it is broken into four subregions, and the process continues recursively until all subregions are homogeneous. The traditional quadtree suffers from dependence on the underlying grid. The grid coordinate system is implicit, and therefore fixed. The fixed coordinate system implies a rigid tree. A rigid tree cannot be translated, scaled, or rotated. Instead, a new tree must be built which is the result of one of these transformations. This dissertation introduces the independent quadtree. The independent quadtree is free of any underlying coordinate system. The tree is no longer rigid and can be easily translated, scaled, or rotated. Algorithms to perform these operations axe presented. The translation and rotation algorithms take constant time. The scaling algorithm has linear time in the number nodes in the tree. The disadvantage of independent quadtrees is the longer generation and display time. This dissertation also introduces an alternate method of hierarchical decomposition. This new method finds the largest homogeneous block with respect to the corners of the image. This block defines the division point for the decomposition. If the size of the block is below some cutoff point, it is deemed to be to small to make the overhead worthwhile and the traditional method is used instead. This new method is compared to the traditional method on randomly generated rectangles, triangles, and circles. The new method is shown to use significantly less space for all three ...
Date: December 1986
Creator: Atwood, Larry D. (Larry Dale)
Partner: UNT Libraries

GenoGraphics for OpenWindows

Description: GenoGraphics is a generic utility for constructing and querying one-dimensional linear plots. The outgrowth of a request from Dr. Cassandra Smith for a tool to facilitate her genome mapping research. GenoGraphics development has benefited from a continued collaboration with her. Written in Sun Microsystem's OpenWindows environment and the BTOL toolkit developed at Argonne National Laboratory. GenoGraphics provides an interactive, intuitive, graphical interface. Its features include: viewing multiple maps simultaneously, zooming, and querying by mouse clicking. By expediting plot generation, GenoGraphics gives the scientist more time to analyze data and a novel means for deducing conclusions.
Date: April 1992
Creator: Hagstrom, Ray; Michaels, George S.; Taylor, Ronald; Price, Morgan; Overbeek, Ross; Zawada, Dave et al.
Partner: UNT Libraries Government Documents Department

An investigation of the effects of presentation format and time pressure on decision makers performing tasks of varying complexitites

Description: The primary objective of this study was to determine which presentation format leads to better decision performance when the decision maker solving a problem of certain complexity is experiencing a certain level of time pressure.
Date: December 1990
Creator: Hwang, Mark I. (Mark Ing-Hwa)
Partner: UNT Libraries

Alpha Dithering to Correct Low-Opacity 8 Bit Compositing Errors

Description: This paper describes and analyzes a dithering technique for accurately specifying small values of opacity ({alpha}) that would normally not be possible because of the limited number of bits available in the alpha channel of graphics hardware. This dithering technique addresses problems related to compositing numerous low-opacity semitransparent polygons to create volumetric effects with graphics hardware. The paper also describes the causes and a possible solution to artifacts that arise from parallel or distributed volume rendering using bricking on multiple GPU's.
Date: March 31, 2003
Creator: Williams, P L; Frank, R J & LaMar, E C
Partner: UNT Libraries Government Documents Department

Shiva: An astronomical data analysis framework

Description: A key online and off-line software component of the Sloan Digital Sky Survey (SDSS) is Shiva. Shiva provides a readily extendible framework upon which the SDSS data reduction pipeline software is built. In this paper we present an introduction to the Shiva data analysis framework. We briefly discuss the features and the inherent prototyping and rapid development capabilities that make Shiva an integral part in the on-going development of SDSS software.
Date: December 1, 1995
Creator: Sergey, G.; Berman, E.; Huang, C.H.; Kent, S.; Newberg, H; Nicinski, T. et al.
Partner: UNT Libraries Government Documents Department

Status of the HEPVis class library

Description: Since 1994 a group of High Energy Physicists and Computer Scientists have been collaborating on HEPVis, a library of 2-D and 3-D shapes for detector visualization and HEP analysis. Based on the Open Inventor (1) toolkit, HEPVis has grown into an international collaboration since its inception in 1994. This paper describes the library, its history, and its future. Images from HEP applications that use the library are also included.
Date: March 3, 1999
Creator: al., Amber Boehnlein et
Partner: UNT Libraries Government Documents Department

SCALE Graphical Developments for Improved Criticality Safety Aalyses

Description: New computer graphic developments at Oak Ridge National Ridge National Laboratory (ORNL) are being used to provide visualization of criticality safety models and calculational results as well as tools for criticality safety analysis input preparation. The purpose of this paper is to present the status of current development efforts to continue to enhance the SCALE (Standardized Computer Analyses for Licensing Evaluations) computer software system. Applications for criticality safety analysis in the areas of 3-D model visualization, input preparation and execution via a graphical user interface (GUI), and two-dimensional (2-D) plotting of results are discussed.
Date: September 20, 1999
Creator: Barnett, D. L.; Bowman, S. M.; Horwedel, J. E. & Petrie, L. M.
Partner: UNT Libraries Government Documents Department

General Purpose Programming on Modern Graphics Hardware

Description: I start with a brief introduction to the graphics processing unit (GPU) as well as general-purpose computation on modern graphics hardware (GPGPU). Next, I explore the motivations for GPGPU programming, and the capabilities of modern GPUs (including advantages and disadvantages). Also, I give the background required for further exploring GPU programming, including the terminology used and the resources available. Finally, I include a comprehensive survey of previous and current GPGPU work, and end with a look at the future of GPU programming.
Date: May 2008
Creator: Fleming, Robert
Partner: UNT Libraries

Visual literacy in computer culture: reading, writing, and drawing Logo turtle graphics

Description: This study seeks to explore relationships between Logo turtle graphics and visual literacy by addressing two related questions: (a) can traditional visual literacy concepts, as found in the published literature, be synthesized in terms of Logo turtle graphics, and (b) do the literature and "hands-on" experience with turtle graphics indicate that visual competencies are pertinent to graphics-based electronic communications in computer culture?
Date: August 1989
Creator: Horn, Carin E.
Partner: UNT Libraries

Users Guide and Tutorial for PC-GenoGraphics: Version 1

Description: PC-GenoGraphics is a visual database/query facility designed for reasoning with genomic data. Data are represented to reflect variously accurate notions of the location of their sites, etc., along the length of the genome. Sequence data are efficiently stored and queried via a rather versatile language so that entire sequences of organisms will be treatable as they emerge. Other classes of information, such as function descriptions, are stored in a relational form, and joint queries relating these to sequence properties are supported. All queries result in visual responses that indicate locations along the genome. The results of queries can themselves be promoted to be queryable objects against which further queries can be launched.
Date: December 1992
Creator: Hagstrom, Ray; Overbeek, Ross & Price, Morgan
Partner: UNT Libraries Government Documents Department

DOE/FETC Gasis Project

Description: Technical progress on the GAS IS project during the quarter for contract no. DE-AC21 -93 MC281 39 is described. During this period, work was performed on Task 4 Technology Transfer, Task 7: Software Enhancement, Task 8: Reservoir Data System Updates, and Task 9: Supplemental Reservoir Studies.
Date: November 12, 1998
Creator: Hugman, R. H.
Partner: UNT Libraries Government Documents Department

Streaming Compression of Hexahedral Meshes

Description: We describe a method for streaming compression of hexahedral meshes. Given an interleaved stream of vertices and hexahedral our coder incrementally compresses the mesh in the presented order. Our coder is extremely memory efficient when the input stream documents when vertices are referenced for the last time (i.e. when it contains topological finalization tags). Our coder then continuously releases and reuses data structures that no longer contribute to compressing the remainder of the stream. This means in practice that our coder has only a small fraction of the whole mesh in memory at any time. We can therefore compress very large meshes - even meshes that do not file in memory. Compared to traditional, non-streaming approaches that load the entire mesh and globally reorder it during compression, our algorithm trades a less compact compressed representation for significant gains in speed, memory, and I/O efficiency. For example, on the 456k hexahedra 'blade' mesh, our coder is twice as fast and uses 88 times less memory (only 3.1 MB) with the compressed file increasing about 3% in size. We also present the first scheme for predictive compression of properties associated with hexahedral cells.
Date: February 3, 2010
Creator: Isenburg, M & Courbet, C
Partner: UNT Libraries Government Documents Department

Visualization Tools for Adaptive Mesh Refinement Data

Description: Adaptive Mesh Refinement (AMR) is a highly effective method for simulations that span a large range of spatiotemporal scales, such as astrophysical simulations that must accommodate ranges from interstellar to sub-planetary. Most mainstream visualization tools still lack support for AMR as a first class data type and AMR code teams use custom built applications for AMR visualization. The Department of Energy's (DOE's) Science Discovery through Advanced Computing (SciDAC) Visualization and Analytics Center for Enabling Technologies (VACET) is currently working on extending VisIt, which is an open source visualization tool that accommodates AMR as a first-class data type. These efforts will bridge the gap between general-purpose visualization applications and highly specialized AMR visual analysis applications. Here, we give an overview of the state of the art in AMR visualization research and tools and describe how VisIt currently handles AMR data.
Date: May 9, 2007
Creator: Weber, Gunther H.; Beckner, Vincent E.; Childs, Hank; Ligocki,Terry J.; Miller, Mark C.; Van Straalen, Brian et al.
Partner: UNT Libraries Government Documents Department


Description: The role of images of information (charts, diagrams, maps, and symbols) for effective presentation of facts and concepts is expanding dramatically because of advances in computer graphics technology, increasingly hetero-lingual, hetero-cultural world target populations of information providers, the urgent need to convey more efficiently vast amounts of information, the broadening population of (non-expert) computer users, the decrease of available time for reading texts and for decision making, and the general level of literacy. A coalition of visual performance experts, human engineering specialists, computer scientists, and graphic designers/artists is required to resolve human factors aspects of images of information. The need for, nature of, and benefits of interdisciplinary effort are discussed. The results of an interdisciplinary collaboration are demonstrated in a product for visualizing complex information about global energy interdependence. An invited panel will respond to the presentation.
Date: July 1, 1980
Creator: Marcus, A.
Partner: UNT Libraries Government Documents Department

Volume Rendering for Curvilinear and Unstructured Grids

Description: We discuss two volume rendering methods developed at Lawrence Livermore National Laboratory. The first, cell projection, renders the polygons in the projection of each cell. It requires a global visibility sort in order to composite the cells in back to front order, and we discuss several different algorithms for this sort. The second method uses regularly spaced slice planes perpendicular to the X, Y, or Z axes, which slice the cells into polygons. Both methods are supplemented with anti-aliasing techniques to deal with small cells that might fall between pixel samples or slice planes, and both have been parallelized.
Date: March 5, 2003
Creator: Max, N; Williams, P; Silva, C & Cook, R
Partner: UNT Libraries Government Documents Department

Computer Graphics Primitives and the Scan-Line Algorithm

Description: This paper presents the scan-line algorithm which has been implemented on the Lisp Machine. The scan-line algorithm resides beneath a library of primitive software routines which draw more fundamental objects: lines, triangles and rectangles. This routine, implemented in microcode, applies the A(BC)*D approach to word boundary alignments in order to create an extremely fast, efficient, and general purpose drawing primitive. The scan-line algorithm improves on previous methodologies by limiting the number of CPU intensive instructions and by minimizing the number of words referenced. This paper will describe how to draw scan-lines and the constraints imposed upon the scan-line algorithm by the Lisp Machine's hardware and software.
Date: December 1988
Creator: Myjak, Michael D. (Michael David)
Partner: UNT Libraries

Digital video technology - today and tomorrow: 11th office information technology conference

Description: Digital video is probably computing`s fastest moving technology today. Just three years ago, the zenith of digital video technology on the PC was the successful marriage of digital text and graphics with analog audio and video by means of expensive analog laser disc players and video overlay boards. The state of the art involves two different approaches to fully digital video on computers: hardware-assisted and software-only solutions.
Date: October 1, 1994
Creator: Liberman, J.
Partner: UNT Libraries Government Documents Department

Expanding the Numerical Control Version of Computer Graphics to Include Automatically Computed Machine Feeds and Speeds

Description: The objective of the study is to utilize the cross-sectional computation capabilities of a computer to calculate the revolutions per minute, to determine the volume of metal being removed by the machine cutter at any point in the programmed path, and to output the feed rate that the particular situation requires. The six chapters which present the information are as follows: Chapter I, introduction; Chapter II, analysis of factors affecting the computation of speed and feed rate parameters; Chapter III, organization of the input by the numerical control programmer; Chapter IV, modifications to the computer software; Chapter V, evaluation of the benefits of utilizing computed speed and feed rates; Chapter VI, summary, findings, conclusions, and recommendations.
Date: August 1979
Creator: Berry, Ronny E.
Partner: UNT Libraries

CANVAS: C++ objects for easy graphics on an Evans and Sutherland PS390 terminal

Description: The C++ classes described in this note comprise an attempt to provide an object-oriented approach, and if there was ever a graphics terminal naturally suited to object-oriented programming, the PS390 is it. Since a canvas is not a program but a variable to be used in programs, users can write software to suit their particular needs. By simply declaring canvas variables the application program is provided with an object which accepts data and displays it automatically. Any number of canvases can be placed anywhere on the screen, so data can be viewed in a variety of ways simultaneously. Further, the real-time'' transformation capabilities of the PS390 are activated in one step by connecting'' its external devices, the dials and the puck, to the desired canvas. There is no need for the applications programmer to construct his own function networks, choose names for nodes, and do any of the other administrative tasks laid out in the manuals, including connecting the terminal to a host computer and initializing it. These are handled automatically by the canvases themselves, thus removing this clutter from the application program.
Date: August 27, 1990
Creator: Michelotti, Leo & Kick, Richard
Partner: UNT Libraries Government Documents Department

Procedural content creation and technologies for 3D graphics applications and games.

Description: The recent transformation of consumer graphics (CG) cards into powerful 3D rendering processors is due in large measure to the success of game developers in delivering mass market entertainment software that feature highly immersive and captivating virtual environments. Despite this success, 3D CG application development is becoming increasingly handicapped by the inability of traditional content creation methods to keep up with the demand for content. The term content is used here to refer to any data operated on by application code that is meant for viewing, including 3D models, textures, animation sequences and maps or other data-intensive descriptions of virtual environments. Traditionally, content has been handcrafted by humans. A serious problem facing the interactive graphics software development community is how to increase the rate at which content can be produced to keep up with the increasingly rapid pace at which software for interactive applications can now be developed. Research addressing this problem centers around procedural content creation systems. By moving away from purely human content creation toward systems in which humans play a substantially less time-intensive but no less creative part in the process, procedural content creation opens new doors. From a qualitative standpoint, these types of systems will not rely less on human intervention but rather more since they will depend heavily on direction from a human in order to synthesize the desired content. This research draws heavily from the entertainment software domain but the research is broadly relevant to 3D graphics applications in general.
Access: This item is restricted to UNT Community Members. Login required if off-campus.
Date: May 2005
Creator: Roden, Timothy E.
Partner: UNT Libraries

Theory in Practice: Constructivism and the Technology of Instruction in an Authentic Project-based Computer Class

Description: While literature in areas of constructivism learning theory, use of computer technology in education, and the implementation of project-based learning in the classroom have received widespread attention, there is no reported research that specifically examines the effectiveness of using a project-based learning model for computer technology instruction for pre-service teachers' programs in general, and in art education in particular. Thus, the research problem was to examine through pre- and post-test control-group experimental research design whether two different teaching methods, constructivism teaching approach (project-based learning) and traditional (step-by-step) teaching approach, result in significant differences in learning computer usage, the application of computer technical skills, design projects, and attitudes toward using of technology. The research was conducted at University of North Texas during the fall semester of 2004. Both quantitative and qualitative methods were used to collect the data. The quantitative data, collected from a pre-post test and pre and post questionnaire, was analyzed using a t-test. No significant difference was found between the groups as it relates to computer usage, one aspect of the application of computer technical skills (Photoshop usage), and attitudes towards technology. There was, however, a statistical difference between the groups in the use of the other aspect of computer application technical skills (Illustrator). The qualitative data was collected from three sources, the final design project, the focus group interview, and the reflective papers and summarized quantitatively. A rubric was used to assess the final design project and the scores from the rubric were analyzed using the Mann-Whitney U test. A significant difference was found between the groups as it relates to the assessment of the final project design. The constructivist (project-based learning) group scored higher than the traditional (step-by-step) group. The analysis of the focus group interviews revealed more positive responses for the project-based learning group as ...
Access: This item is restricted to UNT Community Members. Login required if off-campus.
Date: May 2006
Creator: Esmaiel, Yousef Esmaiel
Partner: UNT Libraries

Wavelets on Planar Tesselations

Description: We present a new technique for progressive approximation and compression of polygonal objects in images. Our technique uses local parameterizations defined by meshes of convex polygons in the plane. We generalize a tensor product wavelet transform to polygonal domains to perform multiresolution analysis and compression of image regions. The advantage of our technique over conventional wavelet methods is that the domain is an arbitrary tessellation rather than, for example, a uniform rectilinear grid. We expect that this technique has many applications image compression, progressive transmission, radiosity, virtual reality, and image morphing.
Date: February 25, 2000
Creator: Bertram, M.; Duchaineau, M.A.; Hamann, B. & Joy, K.I.
Partner: UNT Libraries Government Documents Department