Feasibility of using eye tracking to increase resolution for visual telepresence

Visual telepresence seeks to extend existing teleoperative capability by supplying the operator with a 3D interactive view of the remote environment. This is achieved through the use of a stereo camera platform which, through appropriate 3D display devices, provides a distinct image to each eye of the operator, and which is slaved directly from the operator's head and eye movements. However, the resolution within current head mounted displays remains poor, thereby reducing the operator's visual acuity. This paper reports on the feasibility of incorporation of eye tracking to increase resolution and investigates the stability and control issues for such a system. Continuous domain and discrete simulations are presented which indicates that eye tracking provides a stable feedback loop for tracking applications, though some empirical testing (currently being initiated) of such a system will be required to overcome indicated stability problems associated with micro saccades of the human operator.

Influence of Comfort on 3D Selection Task Performance in Immersive Desktop Setups

Immersive virtual environments (IVEs) have the potential to afford natural interaction in the three-dimensional (3D) space around a user. However, interaction performance in 3D mid-air is often reduced and depends on a variety of ergonomics factors, the user's endurance, muscular strength, as well as fitness. In particular, in contrast to traditional desktop-based setups, users often cannot rest their arms in a comfortable pose during the interaction. In this article we analyze the impact of comfort on 3D selection tasks in an immersive desktop setup. First, in a pre-study we identified how comfortable or uncomfortable specific interaction positions and poses are for users who are standing upright. Then, we investigated differences in 3D selection task performance when users interact with their hands in a comfortable or uncomfortable body pose, while sitting on a chair in front of a table while the VE was displayed on a headmounted display (HMD). We conducted a Fitts' Law experiment to evaluate selection performance in different poses. The results suggest that users achieve a significantly higher performance in a comfortable pose when they rest their elbow on the table.

Design and development of compact optical systems = Diseño y desarrollo de sistemas ópticos compactos

Esta tesis considera dos tipos de aplicaciones del diseño óptico: óptica formadora de imagen por un lado, y óptica anidólica (nonimaging) o no formadora de imagen, por otro. Las ópticas formadoras de imagen tienen como objetivo la obtención de imágenes de puntos del objeto en el plano de la imagen. Por su parte, la óptica anidólica, surgida del desarrollo de aplicaciones de concentración e iluminación, se centra en la transferencia de energía en forma de luz de forma eficiente. En general, son preferibles los diseños ópticos que den como resultado sistemas compactos, para ambos tipos de ópticas (formadora de imagen y anidólica). En el caso de los sistemas anidólicos, una óptica compacta permite tener costes de producción reducidos. Hay dos razones: (1) una óptica compacta presenta volúmenes reducidos, lo que significa que se necesita menos material para la producción en masa; (2) una óptica compacta es pequeña y ligera, lo que ahorra costes en el transporte. Para los sistemas ópticos de formación de imagen, además de las ventajas anteriores, una óptica compacta aumenta la portabilidad de los dispositivos, que es una gran ventaja en tecnologías de visualización portátiles, tales como cascos de realidad virtual (HMD del inglés Head Mounted Display). Esta tesis se centra por tanto en nuevos enfoques de diseño de sistemas ópticos compactos para aplicaciones tanto de formación de imagen, como anidólicas. Los colimadores son uno de los diseños clásicos dentro la óptica anidólica, y se pueden utilizar en aplicaciones fotovoltaicas y de iluminación. Hay varios enfoques a la hora de diseñar estos colimadores. Los diseños convencionales tienen una relación de aspecto mayor que 0.5. Con el fin de reducir la altura del colimador manteniendo el área de iluminación, esta tesis presenta un diseño de un colimador multicanal. En óptica formadora de imagen, las superficies asféricas y las superficies sin simetría de revolución (o freeform) son de gran utilidad de cara al control de las aberraciones de la imagen y para reducir el número y tamaño de los elementos ópticos. Debido al rápido desarrollo de sistemas de computación digital, los trazados de rayos se pueden realizar de forma rápida y sencilla para evaluar el rendimiento del sistema óptico analizado. Esto ha llevado a los diseños ópticos modernos a ser generados mediante el uso de diferentes técnicas de optimización multi-paramétricas. Estas técnicas requieren un buen diseño inicial como punto de partida para el diseño final, que será obtenido tras un proceso de optimización. Este proceso precisa un método de diseño directo para superficies asféricas y freeform que den como resultado un diseño cercano al óptimo. Un método de diseño basado en ecuaciones diferenciales se presenta en esta tesis para obtener un diseño óptico formado por una superficie freeform y dos superficies asféricas. Esta tesis consta de cinco capítulos. En Capítulo 1, se presentan los conceptos básicos de la óptica formadora de imagen y de la óptica anidólica, y se introducen las técnicas clásicas del diseño de las mismas. El Capítulo 2 describe el diseño de un colimador ultra-compacto. La relación de aspecto ultra-baja de este colimador se logra mediante el uso de una estructura multicanal. Se presentará su procedimiento de diseño, así como un prototipo fabricado y la caracterización del mismo. El Capítulo 3 describe los conceptos principales de la optimización de los sistemas ópticos: función de mérito y método de mínimos cuadrados amortiguados. La importancia de un buen punto de partida se demuestra mediante la presentación de un mismo ejemplo visto a través de diferentes enfoques de diseño. El método de las ecuaciones diferenciales se presenta como una herramienta ideal para obtener un buen punto de partida para la solución final. Además, diferentes técnicas de interpolación y representación de superficies asféricas y freeform se presentan para el procedimiento de optimización. El Capítulo 4 describe la aplicación del método de las ecuaciones diferenciales para un diseño de un sistema óptico de una sola superficie freeform. Algunos conceptos básicos de geometría diferencial son presentados para una mejor comprensión de la derivación de las ecuaciones diferenciales parciales. También se presenta un procedimiento de solución numérica. La condición inicial está elegida como un grado de libertad adicional para controlar la superficie donde se forma la imagen. Basado en este enfoque, un diseño anastigmático se puede obtener fácilmente y se utiliza como punto de partida para un ejemplo de diseño de un HMD con una única superficie reflectante. Después de la optimización, dicho diseño muestra mejor rendimiento. El Capítulo 5 describe el método de las ecuaciones diferenciales ampliado para diseños de dos superficies asféricas. Para diseños ópticos de una superficie, ni la superficie de imagen ni la correspondencia entre puntos del objeto y la imagen pueden ser prescritas. Con esta superficie adicional, la superficie de la imagen se puede prescribir. Esto conduce a un conjunto de tres ecuaciones diferenciales ordinarias implícitas. La solución numérica se puede obtener a través de cualquier software de cálculo numérico. Dicho procedimiento también se explica en este capítulo. Este método de diseño da como resultado una lente anastigmática, que se comparará con una lente aplanática. El diseño anastigmático converge mucho más rápido en la optimización y la solución final muestra un mejor rendimiento. ABSTRACT We will consider optical design from two points of view: imaging optics and nonimaging optics. Imaging optics focuses on the imaging of the points of the object. Nonimaging optics arose from the development of concentrators and illuminators, focuses on the transfer of light energy, and has wide applications in illumination and concentration photovoltaics. In general, compact optical systems are necessary for both imaging and nonimaging designs. For nonimaging optical systems, compact optics use to be important for reducing cost. The reasons are twofold: (1) compact optics is small in volume, which means less material is needed for mass-production; (2) compact optics is small in size and light in weight, which saves cost in transportation. For imaging optical systems, in addition to the above advantages, compact optics increases portability of devices as well, which contributes a lot to wearable display technologies such as Head Mounted Displays (HMD). This thesis presents novel design approaches of compact optical systems for both imaging and nonimaging applications. Collimator is a typical application of nonimaging optics in illumination, and can be used in concentration photovoltaics as well due to the reciprocity of light. There are several approaches for collimator designs. In general, all of these approaches have an aperture diameter to collimator height not greater than 2. In order to reduce the height of the collimator while maintaining the illumination area, a multichannel design is presented in this thesis. In imaging optics, aspheric and freeform surfaces are useful in controlling image aberrations and reducing the number and size of optical elements. Due to the rapid development of digital computing systems, ray tracing can be easily performed to evaluate the performance of optical system. This has led to the modern optical designs created by using different multi-parametric optimization techniques. These techniques require a good initial design to be a starting point so that the final design after optimization procedure can reach the optimum solution. This requires a direct design method for aspheric and freeform surface close to the optimum. A differential equation based design method is presented in this thesis to obtain single freeform and double aspheric surfaces. The thesis comprises of five chapters. In Chapter 1, basic concepts of imaging and nonimaging optics are presented and typical design techniques are introduced. Readers can obtain an understanding for the following chapters. Chapter 2 describes the design of ultra-compact collimator. The ultra-low aspect ratio of this collimator is achieved by using a multichannel structure. Its design procedure is presented together with a prototype and its evaluation. The ultra-compactness of the device has been approved. Chapter 3 describes the main concepts of optimizing optical systems: merit function and Damped Least-Squares method. The importance of a good starting point is demonstrated by presenting an example through different design approaches. The differential equation method is introduced as an ideal tool to obtain a good starting point for the final solution. Additionally, different interpolation and representation techniques for aspheric and freeform surface are presented for optimization procedure. Chapter 4 describes the application of differential equation method in the design of single freeform surface optical system. Basic concepts of differential geometry are presented for understanding the derivation of partial differential equations. A numerical solution procedure is also presented. The initial condition is chosen as an additional freedom to control the image surface. Based on this approach, anastigmatic designs can be readily obtained and is used as starting point for a single reflective surface HMD design example. After optimization, the evaluation shows better MTF. Chapter 5 describes the differential equation method extended to double aspheric surface designs. For single optical surface designs, neither image surface nor the mapping from object to image can be prescribed. With one more surface added, the image surface can be prescribed. This leads to a set of three implicit ordinary differential equations. Numerical solution can be obtained by MATLAB and its procedure is also explained. An anastigmatic lens is derived from this design method and compared with an aplanatic lens. The anastigmatic design converges much faster in optimization and the final solution shows better performance.

Investigando a compressão da percepção de distância em ambientes virtuais através da comparação entre dispositivos de visualização

The correct distance perception is important for executing various interactive tasks such as navigation, selection and manipulation. It is known, however, that, in general, there is a significant distance perception compression in virtual environments, mainly when using Head-Mounted Displays - HMDs. This perceived distance compression may bring various problems to the applications and even affect in a negative way the utility of those applications that depends on the correct judgment of distances. The scientific community, so far, have not been able to determine the causes of the distance perception compression in virtual environments. For this reason, it was the objective of this work to investigate, through experiments with users, the influence of both the field-of-view - FoV - and the distance estimation methods on this perceived compression. For that, an experimental comparison between the my3D device and a HMD, using 32 participants, seeking to find information on the causes of the compressed perception, was executed. The results showed that the my3D has inferior capabilities when compared to the HMD, resulting in worst estimations, on average, in both the tested estimation methods. The causes of that are believed to be the incorrect stimulus of the peripheral vision of the user, the smaller FoV and the smaller immersion sense, as described by the participants of the experiment.

Corpos tatuados : experiências sensíveis em realidade aumentada móvel

Tese (doutorado)—Universidade de Brasília, Instituto de Artes, Programa de Pós-Graduação em Artes, 2015.

Young children’s experience of visual displays of their artwork

The practice of displaying children's artwork in early childhood classrooms poses a number of questions about the child and his or her visual artwork. This paper focuses on young children’s experiences with the display of their own visual artwork. Following Giorgi's (1985a; 1985b) approach to conducting phenomenological psychological research, 13 children between the ages of 4 and 6 years attending an independent school outside metropolitan Detroit, Michigan (USA) participated in semi-structured interviews as a way of uncovering their lived experiences of seeing their artwork displayed. The study yielded 12 essential themes and from these three key issues and their implications for early childhood art education are explored.

Bicycle helmet wearing among adolescents

Adolescents experience many benefits from bicycling; however, there are also potentially significant injury consequences. One effective counter-measure for the prevention of adolescent bicycling injuries is to promote bicycle helmet wearing. An overview is provided of injury risks of bicycle riding with particular attention to the role of helmet wearing and associated countermeasures such as legislation and school and community approaches. The findings are presented of a study conducted in Australia that examined the effectiveness of a theory-based injury prevention program, Skills for Preventing Injury in Youth (SPIY) for ninth-grade students (age 13 to 14 years). The findings showed a significant, 20.2% decrease in cycling without a helmet among the intervention students (n = 360) and no change for the students in the comparison group (n = 363) after 6 months. In addition, it was found that failing to wear a helmet was significantly associated with engaging in other transport-related risks, being male, having friends who do not wear a helmet and are specific targets of change in the SPIY program, showing a negative attitude toward risk, failing to intervene in friends' risk-taking, and having low knowledge of first aid. Overall, the SPIY program appeared to be an effective theory-based intervention to increase helmet wearing among early adolescents, a group not often targeted in school and community helmet-wearing programs.

ElectricCOW : A simulator for mobile sensors and actuators mounted on herds of cattle

ElectricCOW is a network, animal behaviour and agent simulator designed to allow detailed simulation of an ad-hoc model network built from small mote-like devices called flecks. Detailed radio communications, cattle behaviour and sensor and actuator network modelling allows a closed-loop environment, where the network can influence the behaviour of its mobile platforms.

Advanced mathematical modelling and experimental investigation of new torque arms for shaft-mounted drives

Shaft-mounted gearboxes are widely used in industry. The torque arm that holds the reactive torque on the housing of the gearbox, if properly positioned creates the reactive force that lifts the gearbox and unloads the bearings of the output shaft. The shortcoming of these torque arms is that if the gearbox is reversed the direction of the reactive force on the torque arm changes to opposite and added to the weight of the gearbox overloads the bearings shortening their operating life. In this paper, a new patented design of torque arms that develop a controlled lifting force and counteract the weight of the gearbox regardless of the direction of the output shaft rotation is described. Several mathematical models of the conventional and new torque arms were developed and verified experimentally on a specially built test rig that enables modelling of the radial compliance of the gearbox bearings and elastic elements of the torque arms. Comparison showed a good agreement between theoretical and experimental results.

Bicycle helmet research : CARRS-Q monograph 5

Recent research on bicycle helmets and concerns about how public bicycle hire schemes will function in the context of compulsory helmet wearing laws have drawn media attention. This monograph presents the results of research commissioned by the Queensland Department of Transport and Main Roads to review the national and international literature regarding the health outcomes of cycling and bicycle helmets and examine crash and hospital data. It also includes critical examinations of the methodology used by Voukelatos and Rissel (2010), and estimates the likely effects of possible segmented approaches to bicycle helmet wearing legislation. The research concludes that current bicycle helmet wearing rates are halving the number of head injuries experienced by Queensland cyclists. Helmet wearing legislation discouraged people from cycling when it was first introduced but there is little evidence that it continues to do so. Cycling has significant health benefits and should be encouraged in ways that reduce the risk of the most serious injuries. Infrastructure and speed management approaches to improving the safety of cycling should be undertaken as part of a Safe System approach, but protection of the individual by simple and cost-effective methods such as bicycle helmets should also be part of an overall package of measures.

Psychological determinants of motorcycle helmet use among young adults in Cambodia

Cambodian accident statistics show that motivating motorcyclists to make proper use of a safety helmet is a top priority for road safety policy makers. Yet, currently there is no insight whatsoever in the psychological precursors of helmet use in Cambodia. As such, it remains unclear which variables to target by interventions aimed at promoting the use of safety helmets. Therefore, this study adopted a socio-cognitive perspective towards the examination of helmet use in a sample of Cambodian young adults (N = 344). Two theoretical models, i.e., Health Belief Model and Theory of Planned Behaviour were combined and further complemented with two norm-related variables, i.e., descriptive- and personal norm. Based on the results, two important conclusions can be drawn. Firstly, the sample investigated in this study is clearly favourably disposed towards the use of helmets while riding. Secondly, in decreasing order, helmet use behaviour was found to be determined by the following five key-determinants: perceived behavioural control over a specific set of inhibiting situational factors (i.e., mostly when driving short distances, at night, or when dressed up to go out), perceived behavioural control in general, perceived susceptibility, personal norm, and behavioural intentions. Policy makers are recommended to reevaluate their current behavioural change methods for young adults being favourably disposed towards the use of safety helmets. Rather than focussing on motivation-oriented methods, there is a need for strategies that (1) stimulate the translation of good intentions into the desirable behaviour and (2) encourage young adults not to relapse in case they are exposed to risk facilitating circumstances. These implications will be discussed more in detail.

Developing an international survey of bicycle and helmet usage

The European Union‐funded collaborative network, COST Action TU1101: Towards safer bicycling through optimization of bicycle helmets and usage, aims to increase scientific knowledge about bicycle helmets in regards to traffic safety and to disseminate this knowledge to stakeholders, including cyclists, legislators, manufacturers, and the scientific community. The COST research team has developed a uniform international survey to better understand attitudinal and other factors that may influence bicycle and helmet usage, as well as crash risk. The online survey is being distributed by project partners in Europe, Israel, Australia, and potentially the US and Canada. The survey contains four types of questions: (1) biographical data, (2) frequency of cycling and amount of cycling for different purposes (e.g., commuting, health, recreation) and in different environments (e.g., bicycle trails, bike lanes, on sidewalks, in traffic), (3) frequency and circumstances for use and non‐use of helmets, attitudes and reasons for it, and; (4) crash involvement and level of reporting to the police. While the potential value of comparative data across countries with very different cycling cultures and safety levels is substantial, there are numerous challenges in developing, conducting, and analyzing the results of the survey. This presentation will focus on the scope of the international study, methodological issues and pitfalls of such a collaborative effort, and on initial results from one country (Israel). To illustrate, two findings from the preliminary Israeli survey indicate that: (1) none of the crashes were reported to the police including the ones involving hospital admission. Although underreporting of bicycle crashes by police is well documented in all countries the extent is unknown, and can be extreme. (2) Older riders tend to ride more for health/exercise reasons, while younger riders tend to ride more for commuting. Thus there is an interaction between riders’ age and the place and times of riding.

The effect of a meteorological tower on its top-mounted anemometer

The wind-speed at a site can be measured by installing anemometers on top of meteorological (met) towers. In addition to other sources of error, accelerated airflow, or speed-up, around the top of met towers can cause incorrect anemometer measurements. We consider a particular example where an anemometer was located only 2 tower diameters above the met tower. Using a standard computational fluid-dynamics package, we found the maximum error for this configuration to be 2% of the wind-speed. We conclude that a top-mounted anemometer should be located at the windward side of its met tower, raised 5 diameters above the top. This will reduce speed-up error to less than 1%.