The development of a generic framework for the implementation of a cheap, component-based virtual video-conferencing system

We address the problem of virtual-videoconferencing. The proposed solution is effected in terms of a generic framework based on an in-house Virtual Reality system. The framework is composed of a number of distinct components: model acquisition, head tracking, expression analysis, network transmission and avatar reconstruction. The framework promises to provide a unique, cheap, and fast system for avatar construction, transmission and animation. This approach affords a conversion from the traditional video stream approach to the management of an avatar remotely and consequently makes minimal demands on network resources.

Understanding fish-habitat associations using video observations and sonar imaging

This thesis was motivated by the increasing role of species distribution models in managing marine fishes and their habitats. These models provided new information about fish-habitat associations. However, models are potentially influenced by fish behaviour towards underwater video systems.

Comparing towed and baited underwater video techniques for assessing temperate marine fishes

Accurate estimates of fish species occurrence are important to any species’ assessments and distribution model. With increasing emphasis on nondestructive sampling, underwater video techniques are commonly used without a thorough understanding of their advantages and disadvantages. This study compared data collected from baited remote underwater stereo-video systems (stereo BRUVS) and towed-video systems to determine; (1) the differences between these video techniques in terms of fish assemblages, functional groups (i.e. pelagic carnivore, epibenthic carnivore/omnivore or herbivore) and observability (i.e. conspicuous or cryptic), and (2) what impact do these two techniques have on the interpretation of spatially-explicit, predictive models. We found stereo BRUVS and towedvideo techniques recorded very different assemblages, functional groups and observability categories across structurally complex benthic biological habitats (i.e. macroalgae dominated habitats). However, as the habitat complexity became less (e.g. seagrass and areas with no visible macro-biota) both techniques appeared to provide similar fish assemblage information. We also found considerable differences in the predicted extents of habitat suitability between the two video techniques.

Integrating time-series hydroacoustics and video observations for detecting changes in benthic habitats

The ability to quantify change in marine benthic habitats must be considered a key goal of marine habitat mapping activities. Changes in distribution of distinct suites of benthic biological species may occur as a result of natural or human induced processes and these processes may operate at a range of temporal and spatial scales. It is important to understand natural small scale inter-annual patterns of change in order to separate these signals from potential patterns of longer term change. Work to describe these processes of change from an acoustic remote sensing stand point has thus far been limited due to the relatively recent availability of full coverage swath acoustic datasets and cost pressures associated with multiple surveys of the same area. This paper describes the use of landscape transition analysis as a means to differentiate seemingly random patterns of habitat change from systematic signals of habitat transition at a shallow (10–50 m depth) 18 km2 study area on the temperate Australian continental shelf between the years 2006 and 2007. Supervised classifications for each year were accomplished using independently collected high resolution (3 m cell-size) multibeam echosounder (MBES) and video-derived reference data. Of the 4 representative biotic classes considered, signals of directional systematic changes were observed to occur between a shallow kelp dominated class, a deep sessile invertebrate dominated class and a mixed class of kelp and sessile invertebrates. These signals of change are interpreted as inter-annual variation in the density and depth related extent of canopy forming kelp species at the site, a phenomenon reported in smaller scale temporal studies of the same species. The methods applied in this study provide a detailed analysis of the various components of the traditional change detection cross tabulation matrix allowing identification of the strongest signals of systematic habitat transitions across broad geographical regions. Identifying clear patterns of habitat change is an important first step in linking these patterns to the processes that drive them.

Video capture : pre-service teacher reflection, assessment or both

This paper reports on a small trial with 6 pre-service teachers who videoed their own teaching practices. The pre-service teachers used the tool to reflect on practice and to enhance their own understandings of themselves as teachers. The initial footage was used to by the pre-service teachers to gauge quite specific elements of their teaching: for example, were they asking effective questions, or were they responding appropriately to questions children asked and as always, what management strategies seemed to be working? Critical feedback from other students was initially „less than critical‟, but again over time, this also appeared to sharpen as they had more opportunity to use the technology. Initial embarrassment of being on screen was replaced with a professional approach to seeing the video as a tool for providing the opportunity to systematically deconstruct practices and for providing concrete feedback for improvement. Used in conjunction with teaching preparation courses, the videoed segments of teaching practice could be used to highlight exemplars, to show what actually happens in classrooms and to explain certain practices. Cunningham and Benedetto (2002) state “Recent developments in digital video technologies permit teacher candidates to collect, review, and manipulate video to demonstrate their growth as a professional and as a reflective practitioner.” However, in the development of the trial, the issue was raised by the pre-service teachers that they would be interested in keeping the videos as evidence of their teaching competence to be used in applications for teaching positions. In the small trial, ethics permission had not been gained for that to happen, but it is certainly a valid and viable possibility for the future. Currently prospective employers have to rely on paper applications which respond to selection criteria, evidence from pre-service teachers‟ teaching rounds and the subjective impressions of an interview. If students were able to present a 5 minute segment of them teaching, it might count for much more than any other evidence. Video capture of teaching practice would provide potential employers with an indication of a pre-service teacher‟s management strategies, relationships with children and a snapshot of a pre-service teacher‟s instructional practice. The idea of video-capture as a tool for pre-service teachers to illustrate teaching capabilities will be more fully investigated in this paper.

Qualitative estimation of camera motion parameters from video sequences

We propose a simple technique for extracting camera motion parameters from a sequence of images. The method can estimate qualitatively camera pan, tilt, zoom, roll, and horizontal and vertical tracking. Unlike most other comparable techniques, the present method can distinguish pan from horizontal tracking, and tilt from vertical tracking. The technique can be applied to the automated indexing of video and film sequences.

The visitors guide a simple video reuse application

One of the results of the surge in interest in the internet is the great increase in availability of pictorial and video data. Web browsers such as Netscape give access to an enormous range of such data. In order to make use of large amounts of pictorial and video data, it is necessary to develop indexing and retrieval methods. Pictorial databases have made great progress recently, to the extent that there are now a number of commercially available products. Video databases are now being researched and developed from a number of different viewpoints. Given a general indexing scheme for video, the next step is to reuse clips in further applications. In this paper we present an initial application for the reuse of video clips. The aim of the system is to resequence video clips for a particular application. We have chosen a well-constrained application for this purpose, the aim being to produce a video tour of a campus between designated start and destination points from a set of indexed video clips. We use clips of a guide entering and leaving buildings on our campus, and when visitors select a start location and a destination, the system will retrieve clips suitable for guiding the visitor along the correct path. The system uses an index of spatial relationships of key objects for the video clips to decide which clips provide the correct sequence of motion around the campus. Although the full power of the indexing notation is unnecessary for this simple problem, the results from this initial implementation indicate that the concept could be applicable to more complex problems.

Video abstraction : a systematic review and classification

The demand for various multimedia applications is rapidly increasing due to the recent advance in the computing and network infrastructure, together with the widespread use of digital video technology. Among the key elements for the success of these applications is how to effectively and efficiently manage and store a huge amount of audio visual information, while at the same time providing user-friendly access to the stored data. This has fueled a quickly evolving research area known as video abstraction. As the name implies, video abstraction is a mechanism for generating a short summary of a video, which can either be a sequence of stationary images (keyframes) or moving images (video skims). In terms of browsing and navigation, a good video abstract will enable the user to gain maximum information about the target video sequence in a specified time constraint or sufficient information in the minimum time. Over past years, various ideas and techniques have been proposed towards the effective abstraction of video contents. The purpose of this article is to provide a systematic classification of these works. We identify and detail, for each approach, the underlying components and how they are addressed in specific works. © 2007 ACM.

Video indexing and similarity retrieval by largest common subgraph detection using decision trees

While the largest common subgraph (LCSG) between a query and a database of models can provide an elegant and intuitive measure of similarity for many applications, it is computationally expensive to compute. Recently developed algorithms for subgraph isomorphism detection take advantage of prior knowledge of a database of models to improve the speed of on-line matching. This paper presents a new algorithm based on similar principles to solve the largest common subgraph problem. The new algorithm significantly reduces the computational complexity of detection of the LCSG between a known database of models, and a query given on-line.