Action Recognition in Videos: from Motion Capture Labs to the Web

This paper presents a survey of human action recognition approaches based on visual data recorded from a single video camera. We propose an organizing framework which puts in evidence the evolution of the area, with techniques moving from heavily constrained motion capture scenarios towards more challenging, realistic, "in the wild" videos. The proposed organization is based on the representation used as input for the recognition task, emphasizing the hypothesis assumed and thus, the constraints imposed on the type of video that each technique is able to address. Expliciting the hypothesis and constraints makes the framework particularly useful to select a method, given an application. Another advantage of the proposed organization is that it allows categorizing newest approaches seamlessly with traditional ones, while providing an insightful perspective of the evolution of the action recognition task up to now. That perspective is the basis for the discussion in the end of the paper, where we also present the main open issues in the area.Comment: Preprint submitted to CVIU, survey paper, 46 pages, 2 figures, 4 table

Catalytic water dissociation by greigite Fe3S4surfaces: density functional theory study

The iron sulfide mineral greigite, Fe3S4, has shown promising capability as a hydrogenating catalyst, in particular in the reduction of carbon dioxide to produce small organic molecules under mild conditions. We employed density functional theory calculations to investigate the {001},{011} and {111} surfaces of this iron thiospinel material, as well as the production of hydrogen ad-atoms from the dissociation of water molecules on the surfaces. We systematically analysed the adsorption geometries and the electronic structure of both bare and hydroxylated surfaces. The sulfide surfaces presented a higher flexibility than the isomorphic oxide magnetite, Fe3O4, allowing perpendicular movement of the cations above or below the top atomic sulfur layer. We considered both molecular and dissociative water adsorption processes, and have shown that molecular adsorption is the predominant state on these surfaces from both a thermodynamic and kinetic point of view. We considered a second molecule of water which stabilizes the system mainly by H-bonds, although the dissociation process remains thermodynamically unfavourable. We noted, however, synergistic adsorption effects on the Fe3S4{001} owing to the presence of hydroxyl groups. We concluded that, in contrast to Fe3O4, molecular adsorption of water is clearly preferred on greigite surfaces

Telepathically urban

Proposals for ubiquitous computing have taken a variety of forms, from “utility fogs” to “pervasive networks.” This chapter considers smart dust as a hypothetical and actual proposal made for pervasive computing in an urban context. Proposals for smart dust have been developed in the form of tiny wireless sensors that could be released en masse, so that countless machines are in constant relay, coordinating information about an environment. Wireless sensors, distributed and embedded in environments, move the “information city” from a zone where digital media is produced and circulated by media workers, to a space where the city itself is a site of information generation – an urban information ecology. This sensor technology is less concerned with increasing computing power and more attentive to reducing the size of hardware, a technological shift that would allow millions of tiny machines to be deployed in drifts of simultaneous communication. In order to examine further the modalities of machine-to-machine communication, this chapter engages with the notion of telepathy, or literally, “remote sensation,” which could be seen to be invisible and instant communication beyond the channels of human sense. This is a process of displaced sensation, of sensing in an extraordinary capacity, or of communicating impressions beyond the reach of usual communicative practices. Wireless sensors – particularly in the more hypothetical form of smart dust – perform this removal and rerouting of sensation. Urban ecologies are monitored, programmed, and made into transmittable information, but this sensory information transpires through relatively opaque machinic spaces – and the messages circulated may be decoded as much through conjecture as clear communication. Originally developed through the Culture of Cities project in 2004, this chapter considers urban environments as spaces of informational correspondence, and discusses early notions around the Internet migrating to environmental operations

08141 Abstracts Collection -- Organic Computing - Controlled Self-organization

From March 30th to April 4th 2008, the Dagstuhl Seminar 08141 "Organic Computing - Controlled Self-organization"\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

Cloud animation

Clouds are animate forms, shifting and evanescent, mutable and always in movement. They have also long been a subject of imagery, especially painting, because paint, most notably watercolour, as John Constable knew, seeped into thick drawing papers much as a cloud seeped itself through the sky. The drama of clouds in the 20th century was seized by film and it is striking to note that many Hollywood Studio logos use clouds. Clouds from Constable to the Hollywood logos are Romantic clouds. They drift and float, produce ambience and mood, along with weather. But the cloud appears in the digital age too, in more ways than one. Clouds have been constituted digitally by commercial animation studios and used as main characters in cartoons; they are available in commercial applications, such as architecture and landscaping packages; they have been made and represented by art animators. This body of work, kitsch and dumb as some of it is, is treated in this article as emblematic of an age in which the digital cloud looms as a new substance. The cloud in the digital age is a source of form, like a 3D printer, a source of any imaginable form. As such it comes to be less a metaphor of something else and more a generator of a metaphor that is itself. Now we live alongside – and even inside - a huge cloud metaphor that is The Cloud. In what ways do the clouds in the sky speak across to the platform and matter that is called The Cloud? What is at work in the digitalising of clouds in animation, and the production of animation through the technologies of the Cloud? Are we witnessing the creation of a synthetic heaven into which all production has been relocated and the digital clouds make all the moves? Keywords Cloud, day-dreaming, dust, digital, metaphor, Romanticis

DEVELOPMENT OF A LAGRANGIAN-LAGRANGIAN METHODOLOGY TO PREDICT BROWNOUT DUST CLOUDS

A Lagrangian-Lagrangian dust cloud simulation methodology has been developed to help better understand the complicated two-phase nature of the rotorcraft brownout problem. Brownout conditions occur when rotorcraft land or take off from ground surfaces covered with loose sediment such as sand and dust, which decreases the pilot's visibility of the ground and poses a serious safety of flight risk. The present work involved the development of a comprehensive, computationally efficient three-dimensional sediment tracking method for dilute, low Reynolds number Stokes-type flows. The flow field generated by a helicopter rotor in ground effect operations over a mobile sediment bed was modeled by using an inviscid, incompressible, Lagrangian free-vortex method, coupled to a viscous semi-empirical approximation for the boundary layer flow near the ground. A new threshold model for the onset of sediment mobility was developed by including the effects of unsteady pressure forces that are induced in vortically dominated rotor flows, which can significantly alter the threshold conditions for particle motion. Other important aspects of particle mobility and uplift in such vortically driven dust flows were also modeled, including bombardment effects when previously suspended particles impact the bed and eject new particles. Bombardment effects were shown to be a particularly significant contributor to the mobilization and eventual suspension of large quantities of smaller-sized dust particles, which tend to remain suspended. A numerically efficient Lagrangian particle tracking methodology was developed where individual particle or clusters of particles were tracked in the flow. To this end, a multi-step, second-order accurate time-marching scheme was developed to solve the numerically stiff equations that govern the dynamics of particle motion. The stability and accuracy of this scheme was examined and matched to the characteristics of free-vortex method. One-way coupling of the flow and the particle motion was assumed. Particle collisions were not considered. To help reduce numerical costs, the methodology was implemented on graphic processing units, which gave over an order of magnitude reduction in simulation time without any loss in accuracy. Validation of the methodology was performed against available measurements, including flow field measurements that have been made with laboratory-scale and full-scale rotors in ground effect operations. The predicted dust clouds were also compared against measurements of developing dust clouds produced by a helicopter during taxi-pass and approach-to-touchdown flight maneuvers. The results showed that the problem of brownout is mostly driven by the local action of the rotor wake vortices and the grouping or bundling of vortex filaments near the sediment bed. The possibilities of mitigating the intensity of brownout conditions by diffusing the blade tip vortices was also explored. While other means of brownout mitigation may be possible, enhancing the diffusion of the tip vortices was shown to drastically reduce the quantity of mobilized particles and the overall severity of the brownout dust cloud

Hovering data clouds: A decentralized and self-organizing information system

Abstract. With ever-increasing numbers of cars, traffic congestion on the roads is a very serious economic and environmental problem for our modern society. Existing technologies for traffic monitoring and management require stationary infrastructure. These approaches lack flexibility with respect to system deployment and unpredictable events (e.g., accidents). Moreover, the delivery of traffic reports from radio stations is imprecise and often outdated. In the project AutoNomos we aim at developing a decentralized system for traffic monitoring and managing, based on vehicular ad-hoc networks (VANETs). Our objective is to design a system for traffic forecasting that can deliver faster and more appropriate reactions to unpredictable events. In our design, cars collect traffic information, extract the relevant data, and generate traffic reports. A key concept are so-called Hovering Data Clouds (HDCs), which are based on the insight that many crucial structures in traffic (e.g., traffic jams) lead an existence that is independent of the individual cars they are composed of. The result is an elegant, robust and self-organizing distributed information system. In this paper we demonstrate first experimental results

Research and technology annual report, 1981

Various research and technology activities at Ames Research Center are described. Highlights of these accomplishments indicate the Center's varied and highly productive research efforts for 1981

NASA Thesaurus supplement: A four part cumulative supplement to the 1988 edition of the NASA Thesaurus (supplement 3)

The four-part cumulative supplement to the 1988 edition of the NASA Thesaurus includes the Hierarchical Listing (Part 1), Access Vocabulary (Part 2), Definitions (Part 3), and Changes (Part 4). The semiannual supplement gives complete hierarchies and accepted upper/lowercase forms for new terms