Thesis (Ph. D.)--University of Wisconsin--Madison, 1933. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Heinrich-Heine-Universität, 2007. / Description based on print version record. Includes bibliographical references (p. [217]-223) and index.

Proefschrift-Leyden. / Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, Dept. of English Language and Literature, June 2000. / Includes bibliographical references. Also available on the Internet.

The entertainment industry and research departments feature many applications of crowd simulation. Typically, it does not suffice to simply generate crowds large in number; they must also be realistic in terms of behaviour and visual fidelity, which is far from an easy or computationally cheap task. Because of this, methods to simulate crowds in a realistic manner while keeping complexity at a manageable level must be explored and implemented. Implementing impostors in crowd simulation is a ubiquitous technique for managing rendering complexity. Impostors, 2D image representations of virtual 3D objects, improve performance due to their relative simplicity, and can be implemented with varying resolution depending on performance needs; the lower the image resolution of impostors, the higher the efficiency. Not all crowds are the same, some are denser, while others are sparse. On the same note, the scenarios, and thus viewing perspectives, in which crowds are found vary as well; some crowds are seen at eye-level, others from a bird’s-eye view. This thesis explores how viewers’ sensitivity towards impostor resolution degradation is affected by crowd density and perspective. This is done by conducting a user study in which participants are shown a number video clip pairs. Each pair features clips showing the same crowd scenario, but with one clip only containing high-resolution impostors, and one clip with a gradually increasing share of low-resolution impostors. For each video clip pair, participants are tasked with identifying the one clip containing low-resolution impostors as quickly as possible. The video clip pairs feature different combinations of crowd density and viewing perspective, and the results from the study show that crowd density has a significant effect on viewers sensitivity towards impostor resolution degradation. Although perspective seems to have an indicative effect, it was not found to be significant. / Dagens underhållningsindustri och forskningsvärld har många tillämpningar av folkmassimulering. Vanligtvis räcker det inte att bara simulera folkmassor stora till antalet individer, de måste också vara realistiska vad gäller beteende och visuell trovärdighet, vilket är långt ifrån en lätt eller beräkningsmässigt billig uppgift. Av denna anledning måste metoder för att simulera folkmassor på ett realistiskt sätt, samtidigt som man behåller komplexiteten på en hanterbar nivå, undersökas och implementeras. Denna rapport undersöker och diskuterer i vilken grad detaljnivån hos simulerade folkmassor kan sänkas genom användning av impostors, 2D-representationer av 3D-objekt vilka vanligtvis används när objektet är för långt bort för att betraktare ska kunna särskilja en 3D-modell av objektet från en bild av samma objekt. Alla folkmassor är inte desamma, vissa är tätare, medan andra är glesa. På samma sätt skiljer sig de scenarion, och därmed perspektiven, i vilka massorna återfinns; vissa folkmassor ses på ögonnivå, andra från ett fågelperspektiv. Det undersökta problemet i denna rapport gäller hur tittarnas känslighet mot försämring av impostorupplösning påverkas av folkmassans densitet och perspektivet från vilket de betraktas. Detta görs genom att genomföra en användarstudie där deltagare visas ett antal videoklipp-par. Varje par innehåller klipp som visar samma folkmassescenario, men där endast ett klipp innehåller uteslutande högupplösta impostors, och ett klipp med en gradvis ökande andel av impstors med låg upplösning. För varje videoklipp-par är har studiedeltagarna i uppgift att identifiera det klipp som innehåller lågupplösta impostors så snabbt som möjligt. Videoklipp-paren har olika kombinationer av folkmassodensitet och visningsperspektiv, och resultaten från studien visar att folkmassodensitet har en signifikant effekt på tittarnas känslighet mot försämring av impostorupplösning. Även om perspektiv verkar ha en indikativ effekt, har den inte visat sig vara signifikant.

Interactive software applications which need to render large terrain meshes can suffer from slow frame rates if the geometry of the terrain is sufficiently dense. However, the viewing angle to many distant features of the terrain does not change rapidly with respect to time. If the movement of the viewing position is limited to continuous motion and restrained to a known speed, many terrain features may be rendered once in high detail and reused for several frames. This thesis proposes a method to increase the rendering speed of large complex terrains by splitting the terrain into contiguous chunks. If a given chunk is far enough away from the camera and its viewing angle will not change quickly, it is rendered into an image buffer. This buffer is then used to texture map a simplified version of the terrain mesh. The simplified and textured mesh is rendered in place of the original chunk of geometrically complex terrain. The simplified mesh is used to approximate parallax effects as the viewing angle changes in small increments. This technique is shown to as much as double the rendering speed of large terrain meshes without reducing the quality of the final image.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

This study investigates the phenomenon of impression management in computer-mediated communication (CMC), particularly chat rooms. Past research has overlooked the occurrence of this phenomenon; however, connections can be drawn from the body of research on impression management in face-to-face communication as well as the body of research on CMC. Indeed, impression management is an integral part of chat room interaction.A screening survey was administered to 382 college students to identify those students who interacted in chat rooms regularly and admitted to engaging in impression management and misrepresenting their identities. Ten such students were interviewed. Their accounts were recorded, transcribed, and analyzed using the grounded theory methodology. The analysis revealed that a set of antecedent conditions influence the phenomenon of impression management, which is managed by two action/interactional strategies and results in an outcome. / Department of Speech Communication

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[pt] O presente trabalho introduz o conceito de impostores com relevo: uma maneira eficiente para representar objetos por imagens em sistemas que requerem visualização em tempo real, especialmente jogos 3D e ambientes de realidade virtual. Para tanto, mesclam-se métodos tipicamente pertencentes à área de renderização baseada em imagens com métodos tradicionais de visualização baseada em geometria. A técnica requer do usuário apenas a modelagem geométrica da entidade a ser representada. Posteriormente o sistema sintetiza texturas com relevo, dinamicamente atualizadas quando necessário, e as visualiza utilizando o método de mapeamento de texturas com relevo. Esta abordagem permite inserir modelos complexos, tanto pela sua natureza geométrica, como pelo seu processo de visualização, no pipeline gráfico em tempo real. Além disso, os impostores com relevo procuram aproveitar o tempo ocioso ou recursos paralelos disponíveis no processador, de forma a balancear a carga de processamento de visualização entre CPU/GPU. Estes impostores também tornam possível a representação de qualquer tipo de objeto geométrico através de mapeamento de texturas com relevo. / [en] The present work introduces the concept of relief impostors: an efficient manner of representing objects by images in systems that require real time rendering, such as 3D games and virtual reality environments. For this purpose, typical methods of image-based rendering are mixed with traditional geometry based rendering methods. This technique only requires from the user the geometric modeling of the entity to be represented. After this, the system synthesizes relief textures, dynamically refreshed when necessary, and renders them using the method of relief texture mapping. This approach allows complex models to be inserted into the real time pipeline system. This complexity arise either from the geometric nature of the model or its process of visualization. Also, the relief impostors try to use the idle time or parallel resources available on the processor, in order to balance the work to be done between the CPU and GPU. Furthermore, they make possible the representation of any kind of geometric object by the relief texture mapping technique.