Valerio De Luca

Haptic, Virtual Interaction and Motor Imagery: Entertainment Tools and Psychophysiological Testing

In this work, the perception of affordances was analysed in terms of cognitive neuroscience during an interactive experience in a virtual reality environment. In particular, we chose a virtual reality scenario based on the Leap Motion controller: this sensor device captures the movements of the user’s hand and fingers, which are reproduced on a computer screen by the proper software applications. For our experiment, we employed a sample of 10 subjects matched by age and sex and chosen among university students. The subjects took part in motor imagery training and immersive affordance condition (a virtual training with Leap Motion and a haptic training with real objects). After each training sessions the subject performed a recognition task, in order to investigate event-related potential (ERP) components. The results revealed significant differences in the attentional components during the Leap Motion training. During Leap Motion session, latencies increased in the occipital lobes, which are entrusted to visual sensory; in contrast, latencies decreased in the frontal lobe, where the brain is mainly activated for attention and action planning.

Packet losses and objective video quality metrics in H.264 video streaming

We analyzed PSNR, BIPSNR, SSIM, 3SSIM, MSSSIM, VQM for various packet loss fractions.A lower bitrate mitigates PSNR impairments caused by packet losses.BIPSNR has less probability than PSNR to be significantly influenced by packet losses.Among structural similarity metrics, SSIM is the least affected by packet losses.VQM metric is the most affected by packet losses. Video quality is a key factor in modern video streaming systems. Video compression artifacts affect it but also delay, jitter and packet loss may compromise it. Objective metrics have been proposed to emulate the human visual system: several experimental works have evaluated their adherence to opinions expressed by real users. Instead of dealing with subjective tests, we focused on the effects of network packet losses on objective metrics: since quality metrics are generally computationally intensive, a convenient approach could consist in inferring information about transmission quality from network impairment statistics. We did experimental tests on two computer-animated videos, whose high color contrasts allow a fair comparison between content dependent and content independent metrics. We studied the encoding parameters that minimize/maximize the values of some metrics (PSNR, BI-PSNR, SSIM, 3SSIM, MSSSIM, VQM) for several packet loss percentages. We analyzed also the Empirical Cumulative Density Function of the degradations of quality metrics.

OpenSatRelaying: a Hybrid Approach to Real-Time Audio- Video Distribution over the Internet

 Abstract—In spite of massive research efforts devoted to the advance of the technologies for large-scale live distribution of audio-video IP streams, no totally satisfying solutions seem to have emerged so far. CDNs are still expensive and P2P-TV systems face substantial delay limitations. As the deployment of a global terrestrial IP multicast infrastructure still looks far, turning the attention to satellite-based multicast would seem a sensible choice. However, the cost of such technology has been a stumbling block until now. That is where the CHARMS architecture comes in. It is designed to take advantage of the formidable properties of the satellite without requiring a generic user to install any sort of satellite receiver or dish. Its cornerstone is the recursive terrestrial relaying of satellite streams a number of properly equipped hosts are able to receive. The present paper relates about the results of the OpenSatRelaying project, aimed at the implementation and testing of the CHARMS architecture.

Are P2P streaming systems ready for interactive e-learning?

Peer-to-peer streaming is a well-known technology for the large-scale distribution of audio/video contents. Its widespread adoption derives from the possibility of having a good scalability without the need for the deployment of expensive infrastructures such as Content Delivery Networks (CDNs). We think real-time streaming of lessons could open new interesting opportunities in e-learning systems by encouraging interactivity between teachers and learners. Delay requirements are very strict in interactive e-learning scenarios, where playback lag between the event in the real world and the received audio/video should not exceed a few seconds. Only a very short delay would allow students to ask questions during the lesson. At the same time, playback continuity is a key aspect too, since holes in the stream reproduction could seriously compromise the understanding of lectures. In this paper we compared some solutions that try to overcome the limitations of traditional mesh-based P2P systems, which are usually affected by long and unpredictable delays. We finally tried to outline which of the analyzed solutions appears the most suitable one to meet e-learning requirements.

A Web API Framework for Developing Grid Portals

In this paper we describe a grid problem solving environment we developed for financial applications. We based its development on a portlet framework we have specifically developed and on a set of Web APIs that encapsulate all grid control and computation logic. Even though nowadays grid portals are characterized by various and different features and are implemented in very differing programming languages and technologies, we thought that they have many structural aspects in common. For this reason we decided to design and implement a set of Grid specific Web APIs, that we called GRB WAPI. Through them, a portal developer will not have to deal with grid technical details and will be able to manage a high level design. A portal developer will be able to concentrate on some other aspects that concern presentation, such as portal usability and functionality. We discarded the idea of developing a traditional library in order to free portal developers from a particular implementation technology. Thanks to this choice the portal presentation logic can be implemented in any web technology and can be on a different server

Development of a Virtual Simulator for Microanastomosis: New Opportunities and Challenges

The paper deals with the development of virtual surgical simulator for microanastomosis developed within the INTERREG (Italy-Greece) MICRO project. Microanastomosis is a surgical technique that involves, under optical magnification, the conjunction of blood vessels of a few millimeters diameter and is used also to support the surgical treatment of tumours. This manuscript describes the two principal solutions analysed during the progress of the MICRO project. The first step concerns the development of the simulator using the Unity3D engine; the second step describes an evolution of the surgical simulator to support remote control by a haptic interface via web using the WebGL platform based on JavaScript code. For both, a force feedback module has been implemented that reads data coming from the simulator and converts them to generate a servo control action on the haptic interface. For both solutions, some results of the implemented simulator are described .

Efficient multi-source RTP stream relaying in overlay networks

P2P streaming systems exploit the high scalability of P2P networks to propagate multimedia streams to wide areas in a distributed fashion. A P2P network is made up of several logic connections among peer nodes, which can form a mesh or a tree overlay. Interactive real-time streaming imposes very strict delay constraints: in e-learning environments, for instance, only a high level of synchrony with the live event may allow users to ask questions in real-time to the lecture speaker. Despite their resilience to peer churning, mesh overlays are affected by a high and variable delay, which hampers their adoption in interactive applications. Playback discontinuity, caused by missing chunks, may be a serious problem too, since it may compromise the speech understanding. On the contrary, multi-tree MDC-based overlays can guarantee a smooth playback continuity, since a stream can be fluently reproduced also when some descriptions are lost. The queuing and the elaboration delay of the nodes should be kept under control to reduce the overall end-to-end delay on each tree branch. In this work we describe a framework for the construction of reliable tree overlays: we designed a smooth switch-to-fallback mechanism to quickly replace nodes leaving the overlay, a channel for packet recovery and a very efficient engine that collects MDC descriptions coming from parent nodes. The experimental data we reported in the last section reveal a low CPU usage and a very low elaboration delay in collecting MDC descriptions.

GRB_WAPI, a RESTful Framework for Grid Portals

Abstract Nowadays grid portals are characterized by various and different features and are implemented in very differing programming languages and technologies, still having many structural aspects in common. This paper describes a RESTful Web API, named GRB_WAPI, specifically developed for grid computing that encapsulates all grid control and computation logic need to build a grid portal. Through the adoption of this API a portal developer does not have to deal with grid technical details focusing just on the high level design of her system and on some other aspects that concern presentation, such as portal usability and functionality. The idea of developing a traditional library has been discarded in order to free portal developers from a particular implementation technology. Thanks to this choice the portal presentation logic can be implemented in any web technology and can be deployed on a different server. Traditional Web Services and SOAP protocol approach has been discarded in order to adopt a RESTful approach to make the Web APIs lighter and also to take advantage of some other aspects illustrated in the paper.

Augmented Reality to Understand the Leonardo’s Machines

Augmented reality plays an important role in cultural heritage and education. The magic effect of 3D animated objects can enhance students’ interest, attention and engagement in school subjects. Moreover, augmented reality can help understand spatial concepts and the working principles of complex mechanical components. In such context, machines designed by Leonardo Da Vinci are a perfect case study for augmented reality technologies. This paper presents a mobile augmented reality application developed for an exhibit on Leonardo’s inventions: it shows the overall structure and the working principles of some machines recognized on the pages of the Atlantic Codex. We used Blender to design the animated 3D models of the machines and the ARToolkit and Vuforia frameworks to superimpose virtual models over Leonardo’s sketches framed by the camera of mobile devices. Subjective data about user experience collected through some questionnaires proved how AR applications can improve the dominant learning style in accordance with Kolb’s theory.