Distal pointing is the interaction style defined by directly pointing at targets from a distance. It follows a laser pointer metaphor and the position of the cursor is determined by the intersection of a vector extending the pointing device with the display surface. Distal pointing as a basic interaction style poses several challenges for the user, mainly because of the lack of precision humans have when using it. The focus of this thesis is to understand and improve distal pointing, making it a viable interaction metaphor to be used in a wide variety of applications. We achieve this by proposing and validating a predictive model of distal pointing that is inspired by Fitts' law, but which contains some unique features. The difficulty of a distal pointing task is best described by the angular size of the target and the angular distance that the cursor needs to go across to reach the target from the input device perspective. The practical impact of this is that the user's relative position to the target should be taken into account. Based on the model we derived, we proposed a set of design guidelines for high-precision distal pointing techniques. The main guideline from the model is that increasing the target size is much more important than reducing the distance to the target. In order to improve distal pointing, we followed the model guidelines and designed interaction techniques that aim at improving the precision of distal pointing tasks. Absolute and Relative Mapping (ARM) distal pointing increases precision by offering the user a toggle which changes the control/display (CD) ratio such that a large movement of the input device is mapped to a small movement of the cursor. Dynamic Control Display Ratio (DyCoDiR) automatically increases distal pointing precision, as the user needs it. DyCoDiR takes into account the user distance to the interaction area and the speed at which the user moves the input device to dynamically calculate an increased CD ratio, making the action more precise the steadier the user tries to be. We performed an evaluation of ARM and DyCoDiR comparing them to basic distal pointing in a realistic context. In this experiment, we also provided variations of the techniques which increased the visual perception of targets through zooming in the area around the cursor when precision was needed. Results from the study show that ARM and DyCoDiR are significantly faster and more accurate than basic distal pointing with tasks that require very high precision. We analyzed user navigation strategies and found that the high precision techniques afford users to remain stationary while performing interactions. However, we also found that individual differences have a strong impact on the decision to walk or not, and that, sometimes, is more important than the technique affordance. We provided a validation for the distal pointing model through the analysis of expected difficulty of distal pointing tasks in light of each technique tested. We propose selection by progressive refinement, a new design concept for distal pointing selection techniques, whose goal is to offer the ability to achieve near perfect accuracy in selection at very cluttered environments. The idea of selection by progressive refinement is to gradually eliminate possible targets from the set of selectable objects until only one object is available for selection. We implemented SQUAD, a selection by progressive refinement distal pointing technique, and performed a controlled experiment comparing it to basic distal pointing. We found that there is a clear tradeoff between immediate selections that require high precision and selections by progressive refinement which always require low precision. We validated the model by fitting the distal pointing data and proposed a new model, which has a linear growth in time, for SQUAD selection. / Ph. D.

Der Einsatz großer, vertikaler Displays nimmt sowohl in Bereichen der Forschung als auch der Wirtschaft zu. Diese Displays eignen sich durch ihre Größe und Auflösung unter anderem für die Informationsvisualisierung. Es gibt bereits eine Menge von Forschungsarbeiten, welche die Interaktion mit großen, vertikalen Displays untersucht hat. Jedoch ist speziell die Bedienung Magischer Linsen auf großen Displaywänden weitgehend unbeachtet geblieben. Eine intuitive Interaktion mit Magischen Linsen auf einer Displaywand kann jedoch insbesondere in kollaborativen Szenarien große Vorteile bieten. Smartphones eignen sich durch ihre Portabilität zur Interaktion mit Displaywänden. Unter Verwendung von Mobilgeräten und einer hochauflösenden Displaywand wurden im Rahmen der vorliegenden Arbeit Interaktionskonzepte zur Steuerung und Parametrisierung Magischer Linsen entwickelt. Hierzu wurde eine Recherche des aktuellen Forschungsstandes betrieben und Anwendungsfälle für den Einsatz der Konzepte aufgestellt. Es wurde eine große Bandbreite von Interaktionskonzepten entwickelt, welche von lockeren bis zu fokussierten Interaktionen reichen. Für die Bedienung der Magischen Linsen wurden verschiedene Aktionen identifiziert, welche in einem Interaktionsablauf auftreten und durch die Konzepte zu unterstützen sind. Ein Teil der entwickelten Interaktionskonzepte wurde durch einen Prototypen implementiert und anhand von Beispieldatensätzen getestet. / The usage of large, vertical displays is increasing in felds of research as well as in the economy. Because of their size and resolution these displays are well suited for information visualization. There already are a number of publications which examine the interaction with large, vertical displays. Yet especially the operation of magic lenses on large display walls has been mostly ignored. An intuitive interaction with magic lenses on a large display may be espesially advantageous in collaborative scenarios. Smartphones are suited for interaction with display walls because of their portability. In this paper interaction concepts for operating and parametrizing magic lenses have been developed using mobile devices and a high resolution display wall. For this purpose the current state of research has been investigated and application scenarios for the use of the concepts have been constructed. A big amount of interaction concepts have been developed which range from casual to focused interactions. For the operation of magic lenses several actions have been identifed which occur in an interaction process and have to be adsressed by the concepts. Part of the developed interaction concepts have been implemented by a prototype and tested with sample data sets.

Der Einsatz großer, vertikaler Displays nimmt sowohl in Bereichen der Forschung als auch der Wirtschaft zu. Diese Displays eignen sich durch ihre Größe und Auflösung unter anderem für die Informationsvisualisierung. Es gibt bereits eine Menge von Forschungsarbeiten, welche die Interaktion mit großen, vertikalen Displays untersucht hat. Jedoch ist speziell die Bedienung Magischer Linsen auf großen Displaywänden weitgehend unbeachtet geblieben. Eine intuitive Interaktion mit Magischen Linsen auf einer Displaywand kann jedoch insbesondere in kollaborativen Szenarien große Vorteile bieten. Smartphones eignen sich durch ihre Portabilität zur Interaktion mit Displaywänden. Unter Verwendung von Mobilgeräten und einer hochauflösenden Displaywand wurden im Rahmen der vorliegenden Arbeit Interaktionskonzepte zur Steuerung und Parametrisierung Magischer Linsen entwickelt. Hierzu wurde eine Recherche des aktuellen Forschungsstandes betrieben und Anwendungsfälle für den Einsatz der Konzepte aufgestellt. Es wurde eine große Bandbreite von Interaktionskonzepten entwickelt, welche von lockeren bis zu fokussierten Interaktionen reichen. Für die Bedienung der Magischen Linsen wurden verschiedene Aktionen identifiziert, welche in einem Interaktionsablauf auftreten und durch die Konzepte zu unterstützen sind. Ein Teil der entwickelten Interaktionskonzepte wurde durch einen Prototypen implementiert und anhand von Beispieldatensätzen getestet. / The usage of large, vertical displays is increasing in felds of research as well as in the economy. Because of their size and resolution these displays are well suited for information visualization. There already are a number of publications which examine the interaction with large, vertical displays. Yet especially the operation of magic lenses on large display walls has been mostly ignored. An intuitive interaction with magic lenses on a large display may be espesially advantageous in collaborative scenarios. Smartphones are suited for interaction with display walls because of their portability. In this paper interaction concepts for operating and parametrizing magic lenses have been developed using mobile devices and a high resolution display wall. For this purpose the current state of research has been investigated and application scenarios for the use of the concepts have been constructed. A big amount of interaction concepts have been developed which range from casual to focused interactions. For the operation of magic lenses several actions have been identifed which occur in an interaction process and have to be adsressed by the concepts. Part of the developed interaction concepts have been implemented by a prototype and tested with sample data sets.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / In this thesis, the maneuvering and orientation of an inspection/service satellite is investigated. This thesis will demonstrate a simplified satellite maneuver around another satellite (for docking purposes). This is illustrated with a cart on an air bearing table (frictionless environment) which simplifies the problem to two dimensions. A mathematical model of the system was designed and simulated (Matlab) for this maneuver. With the simulation, different strategies were considered to maneuver the cart in a circle around another object. The conclusion was made that approximating the circle with segments would conserve propellant. This strategy was implemented on the air bearing table.

This work deals with provisioning of communication services via satellites for collectively mobile user groups in a heterogeneous network with several radio access technologies. The extended use of personalised user equipment beyond the coverage of one single terrestrial network by means of a satellite transport link, represents an increasingly important trend in mobile satellite communication. This trend is confirmed by the commercial introduction of broadband satellite communication to mobile terminals mounted on vehicles, trains, ships or aircraft. This work provides a consequent and structured approach for provisioning of services to broadband satellite terminals for mobile user groups and addresses: -- a systematic satellite communication system design process for collective mobile terminals; -- mobile satellite modelling at a wide range of frequencies, including current and potential frequencies; -- an optimised Pointing Acquisition and Tracking (PAT) system design including characterisation of moments for vehicle types of all mobile scenarios; -- a general hierarchical multi-service dimensioning methodology for collectively mobile user groups, including voice, data, and multimedia services; -- an aeronautical system dimensioning scheme with (capacity and handover) requirements analysis and evaluation of results for different satellite scenarios.

No description available.

[pt] Os satélites de um sistema de comunicações que opera numa determinada faixa de frequências utilizando satélites não-geoestacionários podem sofrer interferências indesejáveis provocadas por transmissores do Serviço Fixo Terrestre (SF) que operam nessa mesma faixa. Para o operador do sistema não geoestacionário é importante identificar quais as áreas da superfície da Terra que contêm os transmissores responsáveis por essas interferências indesejáveis, o que seria um primeiro passo na tentativa de resolver o problema através de negociações bilaterais com as estações transmissoras do SF envolvidas (coordenação). O presente trabalho apresenta a modelagem matemática do problema, e propõe que a identificação dessas áreas seja feita por meio da estimação das potências e apontamentos (ângulos de azimute e elevação) das antenas transmissoras do SF com base em medidas de potência tomadas nos diversos feixes de recepção de um satélite de teste. O trabalho analisa aspectos específicos do problema e propõe a utilização do Filtro de Kalman Estendido (EKF) para a estimação das potências e apontamentos das antenas transmissoras do SF. / [en] Satellites of a non-geostationary communication system may be victims of harmful interference produced by terrestrial fixed service (FS) transmitting stations operating in the same frequency band. It is important to the satellite system operator to identify the specific areas on Earth s surface containing the FS stations that are responsible for such interference. This would be a first step for solving the problem via bilateral coordination with each of the involved FS operators. This dissertation presents a mathematical model for the problem and proposes that the identification of these areas be made though the estimation of the transmitted power and the antenna pointing (azimuth and elevation angles) of the various FS stations, based on received power measurements taken on the beams of a test non-GSO satellite. This work also investigates the particular aspects of the problem and proposes the Extended Kalman Filter (EKF) as the algorithm for estimation.

While shopping in a retail store today the customers are often interacting with multiple sale channels when making a purchase. These channels can include in‑store terminals, the customers’ smartphone etc. This thesis looks at how physical mobile interaction can be implemented to enhance the experience when using different channels for a purchase. Physical mobile interaction is a way for a user to interact with real world objects using a mobile device. This thesis examines how some of these techniques can be used in a retail store using the customers’ own smartphone device. With todays smartphone market with several different operating systems available it is important to find find an implementation which suits the majority of the users. This paper details which technologies that are available to implement the physical mobile interaction on the major smartphone platforms. It also discusses important design decisions for it to work on these platforms. The paper concludes that it is possible to implement these techniques on todays major smartphone platforms. It also concludes that the best technology can not always be used because of limitations on one or more platforms.

As new input devices are introduced to the technological market and an increasing part of the population are familiar with the usage of digital devices, it may seem difficult to know which input devices to aim for when developing new programs and applications that use graphical interfaces. According to a previous study in this area, the computer mouse was the most preferred and performed best when tested in speed and accuracy when compared to the keyboard and drawing tablet even though the keyboard was the device most were familiar with. This paper attempted to recreate the study with the exception of testing morethings, such as number of miss-clicks, distance travelled, directional changes and time. The keyboard was replaced by a handheld controller as well. The results were that the mouse performed best yet again, and proved to be easy to use efficiently for both new and experienced users. The handheld controller was shown not to be an optimal pointing device, mostly due to it being stuck to a fixed speed and not able to accelerate. It did well in the matter of amount off miss-clicks and directional changes, which can be tied to its slow speed. The drawing tablet was well received by the new users and experienced as more accurate than the handheld device. Its results suggest that the drawing tablet could be an efficient pointing device than proven here in the hands of an experienced user, but for new users it could not perform as well as the mouse device overall. / Eftersom nya inmatningsenheter introduceras på den tekniska marknaden och en större del av befolkningen bekantar sig med användningen av digitala enheter, kan det verka svårt att veta vilka inmatningsenheter man ska rikta sig till när man utvecklar nya program och applikationer som använder grafiskt gränssnitt. Enligt en tidigare studie var datormusen den mest föredragna enheten och fick bäst resultat inom snabbhet och noggrannhet, jämfört med tangentbordet och ritplattan inom detta område, trots att tangentbordet var den enhet som de flesta var bekanta med. Denna undersökning försökte återskapa studien med undantaget att testa flera egenskaper, såsom antal missade klickar, avstånd, byten av färdriktning och tid samt att tangentbordet ersattes av en handhållen kontroller. Resultaten var att musen presterade bäst än en gång och visade sig vara lätt att använda effektivt för både nya och erfarna användare. Den handhållna styrenheten visade sig inte vara en optimal pekdon, främst på grund av att den hade en bestämd hastighet och inte kunde accelerera. Det gick bra i fråga om mängden missade klickar och riktningsförändringar, som kan vara knutna till dess långsamma hastigheten. Ritplattan mottogsväl av de nya användarna och upplevdes som mer exakt än den handhållna enheten. Resultatet tyder på att ritplattan kan vara en effektiv pekdon i händerna på en erfaren användare än bevisat här, men för nya användare kan det inte fungera lika bra som datormusen överlag.

This work deals with provisioning of communication services via satellites for collectively mobile user groups in a heterogeneous network with several radio access technologies. The extended use of personalised user equipment beyond the coverage of one single terrestrial network by means of a satellite transport link, represents an increasingly important trend in mobile satellite communication. This trend is confirmed by the commercial introduction of broadband satellite communication to mobile terminals mounted on vehicles, trains, ships or aircraft. This work provides a consequent and structured approach for provisioning of services to broadband satellite terminals for mobile user groups and addresses: -- a systematic satellite communication system design process for collective mobile terminals; -- mobile satellite modelling at a wide range of frequencies, including current and potential frequencies; -- an optimised Pointing Acquisition and Tracking (PAT) system design including characterisation of moments for vehicle types of all mobile scenarios; -- a general hierarchical multi-service dimensioning methodology for collectively mobile user groups, including voice, data, and multimedia services; -- an aeronautical system dimensioning scheme with (capacity and handover) requirements analysis and evaluation of results for different satellite scenarios.