A semi-local method for iterative depth-map refinement

We present an iterative hierarchical algorithm for multi-view stereo. The algorithm attempts to utilise as much contextual information as is available to compute highly accurate and robust depth maps. There are three novel aspects to the approach: 1) firstly we incrementally improve the depth fidelity as the algorithm progresses through the image pyramid; 2) secondly we show how to incorporate visual hull information (when available) to constrain depth searches; and 3) we show how to simultaneously enforce the consistency of the depth-map by continual comparison with neighbouring depth-maps. We show that this approach produces highly accurate depth-maps and, since it is essentially a local method, is both extremely fast and simple to implement.

Teen content creators : experiences of using information to learn

As access to networked digital communities increases, a growing number of teens participate in digital communities by creating and sharing a variety of content. The affordances of social media - ease of use, ubiquitous access, and communal nature - have made creating and sharing content an appealing process for teens. Teens primarily learn the practices of encountering and using information through social interaction and participation within digital communities. This article adopts the position that information literacy is the experience of using information to learn. It reports on an investigation into teens experiences in the United States, as they use information to learn how to create content and participate within the context of social media. Teens that participate in sharing art on sites such as DeiviantArt, website creation, blogging, and/or posting edited videos via YouTube and Vimeo, were interviewed. The interviews explored teens' information experiences within particular social and digital contexts. Teens discussed the information they used, how information was gathered and accessed, and explored the process of using that information to participate in the communities.

Preparing general technology teachers in China for new roles and responsibilities

This paper discusses the conceptualization, implementation and initial findings of a professional learning program (PLP) which used LEGO® robotics as one of the tools for teaching general technology (GT)in China’s secondary schools. The program encouraged teachers to design learning environments that can be realistic, authentic, engaging and fun. 100 general technology teachers from high schools in 30 provinces of China participated. The program aimed to transform teacher classroom practice, change their beliefs and attitudes, allow teachers to reflect deeply on what they do and in turn to provide their students with meaningful learning. Preliminary findings indicate that these teachers had a huge capacity for change. They were open-minded and absorbed new ways of learning and teaching. They became designers who developed innovative models of learning which incorporated learning processes that effectively used LEGO® robotics as one of the more creative tools for teaching GT.

Less but more : weaving disparate disciplines together for learners to construct their own knowledge

This paper reports on a Professional Learning Program conducted in China with 140 general technology teachers. It aimed to integrate robotics technology across and within the disciplines of science, technology, engineering and mathematics. With the help of university facilitators teachers developed General Technology lessons that seamlessly integrated with rich learning content across disciplines. Teachers engaged in seminars and workshops, which provided the opportunities for them to actively couch sound principles of learning in their daily work. They gained first-hand experience in applying an aligned system of assessments, standards and quality learning experiences geared to the needs of each student. Teachers worked collaboratively in teams to create inquiry, design and collaborative learning activities that aligned with their curriculum and which dealt with real world problems, issues and challenges. They continually discussed and reflected deeply on the activities and shared the newly developed resources online with teachers across the entire country. It is evident from the preliminary analysis of data that teachers are beginning to apply rich pedagogical practices and are becoming ‘adaptive’ in their approach when using LEGO® robotic tools to design, redesign, create and re-create learning activities for their students.

A two week persistent navigation and mapping experiment using RatSLAM : insights and current developments

One of the major challenges in achieving long term robot autonomy is the need for a SLAM algorithm that can perform SLAM over the operational lifetime of the robot, preferably without human intervention or supervision. In this paper we present insights gained from a two week long persistent SLAM experiment, in which a Pioneer robot performed mock deliveries in a busy office environment. We used the biologically inspired visual SLAM system, RatSLAM, combined with a hybrid control architecture that selected between exploring the environment, performing deliveries, and recharging. The robot performed more than a thousand successful deliveries with only one failure (from which it recovered), travelled more than 40 km over 37 hours of active operation, and recharged autonomously 23 times. We discuss several issues arising from the success (and limitations) of this experiment and two subsequent avenues of work.

The uses of multilingualism in digital culture : the case of inter-language linking

Language-use has proven to be the most complex and complicating of all Internet features, yet people and institutions invest enormously in language and crosslanguage features because they are fundamental to the success of the Internet’s past, present and future. The thesis takes into focus the developments of the latter – features that facilitate and signify linking between or across languages – both in their historical and current contexts. In the theoretical analysis, the conceptual platform of inter-language linking is developed to both accommodate efforts towards a new social complexity model for the co-evolution of languages and language content, as well as to create an open analytical space for language and cross-language related features of the Internet and beyond. The practiced uses of inter-language linking have changed over the last decades. Before and during the first years of the WWW, mechanisms of inter-language linking were at best important elements used to create new institutional or content arrangements, but on a large scale they were just insignificant. This has changed with the emergence of the WWW and its development into a web in which content in different languages co-evolve. The thesis traces the inter-language linking mechanisms that facilitated these dynamic changes by analysing what these linking mechanisms are, how their historical as well as current contexts can be understood and what kinds of cultural-economic innovation they enable and impede. The study discusses this alongside four empirical cases of bilingual or multilingual media use, ranging from television and web services for languages of smaller populations, to large-scale, multiple languages involving web ventures by the British Broadcasting Corporation, the Special Broadcasting Service Australia, Wikipedia and Google. To sum up, the thesis introduces the concepts of ‘inter-language linking’ and the ‘lateral web’ to model the social complexity and co-evolution of languages online. The resulting model reconsiders existing social complexity models in that it is the first that can explain the emergence of large-scale, networked co-evolution of languages and language content facilitated by the Internet and the WWW. Finally, the thesis argues that the Internet enables an open space for language and crosslanguage related features and investigates how far this process is facilitated by (1) amateurs and (2) human-algorithmic interaction cultures.

CAT-SLAM : probabilistic localisation and mapping using a continuous appearance-based trajectory

This paper describes a new system, dubbed Continuous Appearance-based Trajectory Simultaneous Localisation and Mapping (CAT-SLAM), which augments sequential appearance-based place recognition with local metric pose filtering to improve the frequency and reliability of appearance-based loop closure. As in other approaches to appearance-based mapping, loop closure is performed without calculating global feature geometry or performing 3D map construction. Loop-closure filtering uses a probabilistic distribution of possible loop closures along the robot’s previous trajectory, which is represented by a linked list of previously visited locations linked by odometric information. Sequential appearance-based place recognition and local metric pose filtering are evaluated simultaneously using a Rao–Blackwellised particle filter, which weights particles based on appearance matching over sequential frames and the similarity of robot motion along the trajectory. The particle filter explicitly models both the likelihood of revisiting previous locations and exploring new locations. A modified resampling scheme counters particle deprivation and allows loop-closure updates to be performed in constant time for a given environment. We compare the performance of CAT-SLAM with FAB-MAP (a state-of-the-art appearance-only SLAM algorithm) using multiple real-world datasets, demonstrating an increase in the number of correct loop closures detected by CAT-SLAM.

Wind-energy based path planning for electric unmanned aerial vehicles using Markov Decision Processes

Exploiting wind-energy is one possible way to ex- tend flight duration for Unmanned Arial Vehicles. Wind-energy can also be used to minimise energy consumption for a planned path. In this paper, we consider uncertain time-varying wind fields and plan a path through them. A Gaussian distribution is used to determine uncertainty in the Time-varying wind fields. We use Markov Decision Process to plan a path based upon the uncertainty of Gaussian distribution. Simulation results that compare the direct line of flight between start and target point and our planned path for energy consumption and time of travel are presented. The result is a robust path using the most visited cell while sampling the Gaussian distribution of the wind field in each cell.

Reducing Actuator Switchings for Motion Control of Autonomous Underwater Vehicles

A priority when designing control strategies for autonomous underwater vehicles is to emphasize their cost of implementation on a real vehicle. Indeed, due to the vehicles' design and the actuation modes usually under consideration for underwater plateforms the number of actuator switchings must be kept to a small value to insure feasibility and precision. This is the main objective of the algorithm presented in this paper. The theory is illustrated on two examples, one is a fully actuated underwater vehicle capable of motion in six-degrees-of freedom and one is minimally actuated with control motions in the vertical plane only.

Controlling Minimally-Actuated Vehicles for Applications in Ocean Observation

Establishing a persistent presence in the ocean with an AUV to observe temporal variability of large-scale ocean processes requires a unique sensor platform. In this paper, we propose a strategy that utilizes ocean model predictions to increase the autonomy and control of Lagrangian or profiling floats for precisely this purpose. An A* planner is applied to a local controllability map generated from predictions of ocean currents to compute a path between prescribed waypoints that has the highest likelihood of successful execution. The control to follow the planned path is computed by use of a model predictive controller. This controller is designed to select the best depth for the vehicle to exploit ambient currents to reach the goal waypoint. Mission constraints are employed to simulate a practical data collection mission. Results are presented in simulation for a mission off the coast of Los Angeles, CA USA, and show surprising results in the ability of a Lagrangian float to reach a desired location.

Development of distributed fuzzy systems with a runtime-adaptable mobile components framework

A distributed fuzzy system is a real-time fuzzy system in which the input, output and computation may be located on different networked computing nodes. The ability for a distributed software application, such as a distributed fuzzy system, to adapt to changes in the computing network at runtime can provide real-time performance improvement and fault-tolerance. This paper introduces an Adaptable Mobile Component Framework (AMCF) that provides a distributed dataflow-based platform with a fine-grained level of runtime reconfigurability. The execution location of small fragments (possibly as little as few machine-code instructions) of an AMCF application can be moved between different computing nodes at runtime. A case study is included that demonstrates the applicability of the AMCF to a distributed fuzzy system scenario involving multiple physical agents (such as autonomous robots). Using the AMCF, fuzzy systems can now be developed such that they can be distributed automatically across multiple computing nodes and are adaptable to runtime changes in the networked computing environment. This provides the opportunity to improve the performance of fuzzy systems deployed in scenarios where the computing environment is resource-constrained and volatile, such as multiple autonomous robots, smart environments and sensor networks.

Studying Mobile Media : Cultural Technologies, Mobile Communication, and the iPhone

The iPhone represents an important moment in both the short history of mobile media and the long history of cultural technologies. Like the Walkman of the 1980s, it marks a juncture in which notions about identity, individualism, lifestyle and sociality require rearticulation. This book explores not only the iPhone’s particular characteristics, uses and "affects," but also how the "iPhone moment" functions as a barometer for broader patterns of change. In the iPhone moment, this study considers the convergent trajectories in the evolution of digital and mobile culture, and their implications for future scholarship. Through the lens of the iPhone—as a symbol, culture and a set of material practices around contemporary convergent mobile media—the essays collected here explore the most productive theoretical and methodological approaches for grasping media practice, consumer culture and networked communication in the twenty-first century.

Studying the mobile : locating the field

Book Description: The iPhone represents an important moment in both the short history of mobile media and the long history of cultural technologies. Like the Walkman of the 1980s, it marks a juncture in which notions about identity, individualism, lifestyle and sociality require rearticulation. this book explores not only the iPhone’s particular characteristics, uses and "affects," but also how the "iPhone moment" functions as a barometer for broader patterns of change. In the iPhone moment, this study considers the convergent trajectories in the evolution of digital and mobile culture, and their implications for future scholarship. Through the lens of the iPhone—as a symbol, culture and a set of material practices around contemporary convergent mobile media—the essays collected here explore the most productive theoretical and methodological approaches for grasping media practice, consumer culture and networked communication in the twenty-first century.

A tutorial on visual servo control

This article provides a tutorial introduction to visual servo control of robotic manipulators. Since the topic spans many disciplines our goal is limited to providing a basic conceptual framework. We begin by reviewing the prerequisite topics from robotics and computer vision, including a brief review of coordinate transformations, velocity representation, and a description of the geometric aspects of the image formation process. We then present a taxonomy of visual servo control systems. The two major classes of systems, position-based and image-based systems, are then discussed in detail. Since any visual servo system must be capable of tracking image features in a sequence of images, we also include an overview of feature-based and correlation-based methods for tracking. We conclude the tutorial with a number of observations on the current directions of the research field of visual servo control.

Machine vision toolbox for MATLAB, release 3 [Software]

The Toolbox, combined with MATLAB ® and a modern workstation computer, is a useful and convenient environment for investigation of machine vision algorithms. For modest image sizes the processing rate can be sufficiently ``real-time'' to allow for closed-loop control. Focus of attention methods such as dynamic windowing (not provided) can be used to increase the processing rate. With input from a firewire or web camera (support provided) and output to a robot (not provided) it would be possible to implement a visual servo system entirely in MATLAB. Provides many functions that are useful in machine vision and vision-based control. Useful for photometry, photogrammetry, colorimetry. It includes over 100 functions spanning operations such as image file reading and writing, acquisition, display, filtering, blob, point and line feature extraction, mathematical morphology, homographies, visual Jacobians, camera calibration and color space conversion.