14 research outputs found
Faculty Publications and Creative Works 1997
One of the ways we recognize our faculty at the University of New Mexico is through this annual publication which highlights our faculty\u27s scholarly and creative activities and achievements and serves as a compendium of UNM faculty efforts during the 1997 calendar year. Faculty Publications and Creative Works strives to illustrate the depth and breadth of research activities performed throughout our University\u27s laboratories, studios and classrooms. We believe that the communication of individual research is a significant method of sharing concepts and thoughts and ultimately inspiring the birth of new of ideas. In support of this, UNM faculty during 1997 produced over 2,770 works, including 2,398 scholarly papers and articles, 72 books, 63 book chapters, 82 reviews, 151 creative works and 4 patents. We are proud of the accomplishments of our faculty which are in part reflected in this book, which illustrates the diversity of intellectual pursuits in support of research and education at the University of New Mexico. Nasir Ahmed Interim Associate Provost for Research and Dean of Graduate Studie
Enhancing detailed haptic relief for real-time interaction
The present document exposes a different approach for haptic rendering, defined as the simulation of force interactions to reproduce the sensation of surface relief in dense models. Current research shows open issues in timely haptic interaction involving large meshes, with several problems affecting performance and fidelity, and without a dominant technique to treat these issues properly.
Relying in pure geometric collisions when rendering highly dense mesh models (hundreds of thousands of triangles) sensibly degrades haptic rates due to the sheer number of collisions that must be tracked between the mesh's faces and a haptic probe. Several bottlenecks were identified in order to enhance haptic performance: software architecture and data structures, collision detection, and accurate rendering of surface relief.
To account for overall software architecture and data structures, it was derived a complete component framework for transforming standalone VR applications into full-fledged multi-threaded Collaborative Virtual Reality Environments (CVREs), after characterizing existing implementations into a feature-rich superset. Enhancements include: a scalable arbitrated peer-to-peer topology for scene sharing; multi-threaded components for graphics rendering, user interaction and network communications; a collaborative user interface model for session handling; and interchangeable user roles with multi-camera perspectives, avatar awareness and shared annotations. We validate the framework by converting the existing ALICE VR Navigator into a complete CVRE, showing good performance in collaborative manipulation of complex models.
To specifically address collision detection computation, we derive a conformal algebra treatment for collisions among points, segments, areas, and volumes, based on collision detection in conformal R{4,1} (5D) space, and implemented in GPU for faster parallel queries. Results show orders of magnitude time reductions in collisions computations, allowing interactive rates.
Finally, the main core of the research is the haptic rendering of surface mesostructure in large meshes. Initially, a method for surface haptic rendering was proposed, using image-based Hybrid Rugosity Mesostructures (HRMs) of per-face heightfield displacements and normalmaps layered on top of a simpler mesh, adding greater surface detail than actually present. Haptic perception is achieved modulating the haptic probe's force response using the HRM coat. A usability testbed framework was built to measure experimental performance with a common set tests, meshes and HRMs. Trial results show the goodness of the proposed technique, rendering accurate 3D surface detail at high sampling rates.
This local per-face method is extended into a fast global approach for haptic rendering, building a mesostructure-based atlas of depth/normal textures (HyRMA), computed out of surface differences of the same mesh object at two different resolutions: original and simplified. For each triangle in the simplified mesh, an irregular prism is considered defined by the triangle's vertices and their normals. This prism completely covers the original mesh relief over the triangle. Depth distances and surfaces normals within each prism are warped from object volume space to orthogonal tangent space, by means of a novel and fast method for computing barycentric coordinates at the prism, and storing normals and relief in a sorted atlas. Haptic rendering is effected by colliding the probe against the atlas, and effecting a modulated force response at the haptic probe. The method is validated numerically, statistically and perceptually in user testing controlled trials, achieving accurate haptic sensation of large meshes' fine features at interactive rendering rates, with some minute loss of mesostructure detail.En aquesta tesi es presenta un novedós enfocament per a la percepció hà ptica del relleu de models virtuals complexes mitjançant la simulació de les forces d'interacció entre la superfÃcie i un element de contacte. La proposta contribueix a l'estat de l'art de la recerca en aquesta à rea incrementant l'eficiència i la fidelitat de la interacció hà ptica amb grans malles de triangles. La detecció de col·lisions amb malles denses (centenars de milers de triangles) limita la velocitat de resposta hà ptica degut al gran nombre d'avaluacions d'intersecció cara-dispositiu hà ptic que s'han de realitzar. Es van identificar diferents alternatives per a incrementar el rendiment hà ptic: arquitectures de software i estructures de dades especÃfiques, algorismes de detecció de col·lisions i reproducció hà ptica de relleu superficial. En aquesta tesi es presenten contribucions en alguns d'aquests aspectes. S'ha proposat una estructura completa de components per a transformar aplicacions de Realitat Virtual en Ambients Col·laboratius de Realitat Virtual (CRVEs) multithread en xarxa. L'arquitectura proposada inclou: una topologia escalable punt a punt per a compartir escenes; components multithread per a visualització grà fica, interacció amb usuaris i comunicació en xarxa; un model d'interfÃcie d'usuari col·laboratiu per a la gestió de sessions; i rols intercanviables de l'usuari amb perspectives de múltiples cà meres, presència d'avatars i anotacions compartides. L'estructura s'ha validat convertint el navegador ALICE en un CVRE completament funcional, mostrant un bon rendiment en la manipulació col·laborativa de models complexes. Per a incrementar l'eficiència del cà lcul de col·lisions, s'ha proposat un algorisme que treballa en un espai conforme R{4,1} (5D) que permet detectar col·lisions entre punts, segments, triangles i volums. Aquest algorisme s'ha implementat en GPU per obtenir una execució paral·lela més rà pida. Els resultats mostren reduccions en el temps de cà lcul de col·lisions permetent interactivitat. Per a la percepció hà ptica de malles complexes que modelen objectes rugosos, s'han proposat diferents algorismes i estructures de dades. Les denominades Mesoestructures HÃbrides de Rugositat (HRM) permeten substituir els detalls geomètrics d'una cara (rugositats) per dues textures: de normals i d'alçades. La percepció hà ptica s'aconsegueix modulant la força de resposta entre el dispositiu hà ptic i la HRM. Els tests per avaluar experimentalment l'eficiència del cà lcul de col·lisions i la percepció hà ptica utilitzant HRM respecte a modelar les rugositats amb geometria, van mostrar que la tècnica proposada va ser encertada, permetent percebre detalls 3D correctes a altes tases de mostreig. El mètode es va estendre per a representar rugositats d'objectes. Es proposa substituir l'objecte per un model simplificat i un atles de mesoestructures en el que s'usen textures de normals i de relleus (HyRMA). Aquest atles s'obté a partir de la diferència en el detall de la superfÃcie entre dos malles del mateix objecte: l'original i la simplificada. A partir d'un triangle de la malla simplificada es construeix un prisma, definit pels vèrtexs del triangle i les seves normals, que engloba el relleu de la malla original sobre el triangle. Les alçades i normals dins del prisma es transformen des de l'espai de volum a l'espai ortogonal tangent, amb mètode novedós i eficient que calcula les coordenades baricèntriques relatives al prisma, per a guardar el mapa de textures transformat en un atles ordenat. La percepció hà ptica s'assoleix detectant les col·lisions entre el dispositiu hà ptic i l'atles, i modulant la força de resposta d'acord al resultat de la col·lisió. El mètode s'ha validat numèricament, estadÃstica i perceptual en tests amb usuaris, aconseguint una correcta i interactiva sensació tà ctil dels objectes simulats mitjançant la mesoestructura de les mallesEn esta tesis se presenta un enfoque novedoso para la percepción háptica del relieve de modelos virtuales complejos mediante la simulación de las fuerzas de interacción entre la superficie y un elemento de contacto. La propuesta contribuye al estado del arte de investigación en este área incrementando la eficiencia y fidelidad de interacción háptica con grandes mallas de triángulos.
La detección de colisiones con mallas geométricas densas (cientos de miles de triángulos) limita la velocidad de respuesta háptica debido al elevado número de evaluaciones de intersección cara-dispositivo háptico que deben realizarse. Se identificaron diferentes alternativas para incrementar el rendimiento háptico: arquitecturas de software y estructuras de datos especÃficas, algoritmos de detección de colisiones y reproducción háptica de relieve superficial. En esta tesis se presentan contribuciones en algunos de estos aspectos.
Se ha propuesto una estructura completa de componentes para transformar aplicaciones aisladas de Realidad Virtual en Ambientes Colaborativos de Realidad Virtual (CRVEs) multithread en red. La arquitectura propuesta incluye: una topologÃa escalable punto a punto para compartir escenas; componentes multithread para visualización gráfica, interacción con usuarios y comunicación en red; un modelo de interfaz de usuario colaborativo para la gestión de sesiones; y roles intercambiables del usuario con perspectivas de múltiples cámaras, presencia de avatares y anotaciones compartidas. La estructura se ha validado convirtiendo el navegador ALICE en un CVRE completamente funcional, mostrando un buen rendimiento en la manipulación colaborativa de modelos complejos.
Para incrementar la eficiencia del cálculo de colisiones, se ha propuesto un algoritmo que trabaja en un espacio conforme R4,1 (5D) que permite detectar colisiones entre puntos, segmentos, triángulos y volúmenes. Este algoritmo se ha implementado en GPU a efectos
de obtener una ejecución paralelamás rápida. Los resultadosmuestran reducciones en el tiempo de cálculo de colisiones permitiendo respuesta interactiva.
Para la percepción háptica de mallas complejas que modelan objetos rugosos, se han propuesto diferentes algoritmos y estructuras de datos. Las denominadasMesoestructuras HÃbridas de Rugosidad (HRM) permiten substituir los detalles geométricos de una cara (rugosidades) por una textura de normales y otra de alturas. La percepción háptica se consigue modulando la fuerza de respuesta entre el dispositivo háptico y la HRM. Los tests realizados para evaluar experimentalmente la eficiencia del cálculo de colisiones y la percepción
háptica utilizando HRM respecto a modelar las rugosidades con geometrÃa, mostraron que la técnica propuesta fue acertada, permitiendo percibir detalles 3D correctos a altas tasas de muestreo.
Este método anterior es extendido a un procedimiento global para representar rugosidades de objetos. Para hacerlo se propone sustituir el objeto por un modelo simplificado y un atlas de mesostructuras usando texturas de normales y relieves (HyRMA). Este atlas se obtiene de la diferencia en detalle de superficie entre dos mallas del mismo objeto: la original y la simplificada. A partir de un triángulo de la malla simplificada se construye un prisma definido por los vértices del triángulo a lo largo de sus normales, que engloba completamente el relieve de la malla original sobre este triángulo. Las alturas y normales dentro de cada prisma se transforman del espacio de volumen al espacio ortoganal tangente, usando un método novedoso y eficiente que calcula las coordenadas baricéntricas relativas a cada prisma para guardar el mapa de texturas transformado en un atlas ordenado.
La percepción háptica se consigue detectando directamente las colisiones entre el dispositivo háptico y el atlas, y modulando la fuerza de respuesta de acuerdo al resultado de la colisión. El procedmiento se ha validado numérica, estadÃstica y perceptualmente en ensayos con usuarios, consiguiendo a tasas interactivas la correcta sensación táctil de los objetos simulados mediante la mesoestructura de las mallas, con alguna pérdida muy puntual de detall
Design and development of new tactile softness displays for minimally invasive surgery
Despite an influential shortcoming of minimally invasive sugary (MIS), which is the lack of tactile feedback to the surgeon, MIS has increasingly been used in various types of surgeries. Restoring the missing tactile feedback, especially information which can be obtained by the palpation of tissue, such as detection of embedded lump and softness characterization is important in MIS. The present study aims to develop tactile feedback systems both graphically and physically. In graphical rendering approach, the proposed system receives signals from the previously fabricated piezoelectric softness sensors which are integrated with an MIS grasper. After processing the signals, the tactile information is displayed by means of a color coding method. Using the graphical images, the softness of the grasped objects can visually be differentiated. A physical tactile display system is also designed and fabricated. This system simulates non-linear material properties of different soft objects. The system consists of a linear actuator, force and position sensors and processing software. A PID controller is used to control the motion of a linear actuator according to the properties of the simulated material and applied force. Graphical method was also examined to render the tactile information of embedded lumps within a soft tissue/object. The necessary information on the size and location of the hidden features are collected using sensorized MIS graspers. The information is then processed and graphically rendered to the surgeon. Using the proposed system surgeons can identify presence, location and approximate size of hidden lumps by grasping the target object with a reasonable accuracy. Finally, in order to determine the softness of the grasped object, another novel approach is taken by the design and fabrication of a smart endoscopic tool equipped with sensors for measuring the applied force and the angle of the grasper jaws. Using this method, the softness/compliance of the grasped object can be estimated and presented to the surgeo
Life Sciences Program Tasks and Bibliography for FY 1997
This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1997. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive internet web page
Life Sciences Program Tasks and Bibliography
This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1995. Additionally, this inaugural edition of the Task Book includes information for FY 1994 programs. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web pag
Design in the Age of Information: A Report to the National Science Foundation (NSF)
The Information Age is upon us - it has become a global force in our everyday lives. But the promise of significant benefits from this revolution, which has been driven largely by technologists, will not be realized without more careful planning and design of information systems that can be integral to the simultaneously emerging user-cultures. In cultural terms, information systems must be effective, reliable, affordable, intuitively meaningful, and available anytime and everywhere. In this phase of the information revolution, design will be essential
Pour une litterature voyageuse: Travel and Identity in Late Twentieth-Century France
This thesis is a response to the changing nature of French Studies in the UK, and is
also the recognition of the growing need to explore the field's intercultural
dimensions. Although the research for the thesis has been undertaken within the
French department of the School of Cultures, Languages and Area Studies, it is
primarily interdisciplinary, engaging for instance with recent developments in Studies
in Travel Writing, Gender Studies and Translation Studies.
After a period of apparent decline of French travel literature in the 1960s and 1970s,
the geme experienced a resurgence in the 1980s, leading to the launch in 1990 of the
(now major) annual 'Etonnants Voyageurs' festival held in Saint-Malo, the
appearance frqm 1990 of the associated journal Gulliver, and the publication of the
manifesto, Pour une litterature voyageuse, in 1992. The thesis focuses specifically on
critical approaches to the movement, but considers at the same time the wider
phenomena ofliterature in French and postcolonial Francophone identities.
Research Questions
This thesis addre~ses a series of research questions, including: What are the principal
characteristics of travel literature in late twentieth-century France and in particular
that related to the Pour une litterature voyageuse movement? What critical strategies
might be elaborated to approach this material? How has the Pour une litterature
voyageuse movement elaborated an imaginary genealogy, drawing on previous texts
and traditions to project its own identity? What does travel literature in late twentiethcentury
France suggest about national identity and about the need to understand
national identity in intercultural terms? In what ways does travel literature illuminate
issues of gender in late twentieth-century France? What does the shift in emphasis by
this movement towards a litterature-monde signify for travel literature and, on a wider
scale, for the ways in which the boundaries of literature are defined?
Impact of Thesis
This thesis aims to (i) offer a timely and original account of the important Pour une
litterature voyageuse movement, likely to be of interest to scholars in the UK, France
and elsewhere; (ii) elaborate an interdisciplinary and original methodology for the
approach of contemporary travel literature that will be of relevance to those working
in a variety of disciplines; and (iii) explore issues of intercultural communication and
translation, thus contributing to the ongoing redefinition of French Studies in the UK,
and ofthe Modern Languages field more generally
El papel de las pequeñas presas en la dieta humana del PaleolÃtico medio y superior. Una visión diacrónica desde el valle del Ródano al arco mediterráneo.
La incorporació de petites preses a la dieta humana és un tema d’extens debat. Múltiples autors han intentat buscar una explicació sobre quan s’inicia la seva explotació sistemà tica i quines van ser les causes que incentivaren el seu consum regular, especialment a partir del Plistocè superior final. La present tesi doctoral pretén abordar aquestes qüestions a través de l’estudi diacrònic de cinc conjunts arqueològics amb presència de petites preses (lepòrids i aus): Payre, Abri des Pêcheurs, Grotte des Barasses II, la Cova de les Teixoneres i el Molà del Salt. Utilitzant mètodes d’anà lisi basats en la Zooarqueologia i la Tafonomia, les restes de petites preses recuperades han estat avaluades per poder evidenciar el grau d’intervenció humana i d’altres predadors en aquests emplaçaments i observar, aixÃ, possibles patrons en l’explotació d’aquests petits animals. Les dades obtingudes mostren que les condicions paleoecològiques i paleoambientals dels llocs estudiats jugaren un paper molt important en la representació de determinats taxons, i que els canvis ecològics succeïts al llarg del Plistocè superior podrien haver afectat les comunitats faunÃstiques, afavorint l’explotació de taxons que fins al moment eren menys utilitzats en la dieta regular, com les petites preses. No obstant, aquestes circumstà ncies no són exclusives entre si, ja que altres factors com la temporalitat o estacionalitat de les ocupacions, la seva funcionalitat i objectius, les condicions locals de cada lloc, aixà com altres factors socio-culturals podrien també haver afectat a l’espectre dietètic amb independència de la seva cronologia.La incorporación de las pequeñas presas en la dieta humana es un tema de extenso debate. Múltiples autores han intentado buscar una explicación sobre cuándo se inició su explotación sistemática y cuáles fueron las causas que incentivaron su consumo regular, especialmente a partir del Pleistoceno superior final. La presente tesis doctoral pretende abordar estas cuestiones a través del estudio diacrónico de cinco conjuntos arqueológicos con presencia de pequeños animales (lepóridos y aves): Payre, Abri des Pêcheurs, Grotte des Barasses II, Cova de les Teixoneres y Molà del Salt. Utilizando métodos de análisis basados en la ZooarqueologÃa y la TafonomÃa, los restos de pequeñas presas recuperados han sido evaluados para poder evidenciar el grado de intervención humana y de otros predadores en estos emplazamientos y observar, asÃ, posibles patrones en la explotación de estos pequeños animales. Los datos obtenidos muestran que las condiciones paleoecológicas y paleoambientales de cada lugar jugaron un papel importante en la representación de determinados taxones, y que los cambios ecológicos sucedidos a lo largo del Pleistoceno superior pudieron afectar a las comunidades faunÃsticas, favoreciendo la explotación de otros taxones que hasta el momento eran poco utilizados en la dieta regular, como las pequeñas presas. No obstante, estas circunstancias no son exclusivas entre sÃ, ya que otros factores como la temporalidad o estacionalidad de las ocupaciones, su funcionalidad y objetivos, las condiciones locales de cada sitio, asà como otros factores socio-culturales podrÃan también afectar al espectro dietario con independencia de su cronologÃa.The incorporation of small prey in human diets has been a wide topic of discussion. Multiple authors have attempted to identify when the systematic consumption of small prey began and to explain its regular intake, especially in the Late Upper Pleistocene. The present PhD thesis tackles these issues through the diachronic study of five archaeological assemblages containing small prey (leporids and birds): Payre, Abri des Pêcheurs, Grotte des Barasses II, Teixoneres Cave, and Molà del Salt. Using methods based on zooarchaeology and taphonomy, small prey remains were evaluated to demonstrate the involvement of human and non-human predators in these places and thereby to identify the possible exploitation patterns of small prey. The results show that ecology plays an important role in the representation of certain taxa and that the environmental changes during the Upper Pleistocene may have altered faunal populations, promoting the exploitation of other taxa that had previously been less significant to the human diet, such as small prey. However, these circumstances are not exclusive, because factors such as temporality or seasonality of occupation, functionality or objectives, local conditions, and other socio-cultural factors may have also affected the dietary spectrum independent of chronology