Proxy-guided Image-based Rendering for Mobile Devices

VR headsets and hand-held devices are not powerful enough to render complex scenes in real-time. A server can take on the rendering task, but network latency prohibits a good user experience. We present a new image-based rendering (IBR) architecture for masking the latency. It runs in real-time even on very weak mobile devices, supports modern game engine graphics, and maintains high visual quality even for large view displacements. We propose a novel server-side dual-view representation that leverages an optimally-placed extra view and depth peeling to provide the client with coverage for filling disocclusion holes. This representation is directly rendered in a novel wide-angle projection with favorable directional parameterization. A new client-side IBR algorithm uses a pre-transmitted level-of-detail proxy with an encaging simplification and depth-carving to maintain highly complex geometric detail. We demonstrate our approach with typical VR / mobile gaming applications running on mobile hardware. Our technique compares favorably to competing approaches according to perceptual and numerical comparisons

Workload balancing in distributed virtual reality environments

Virtual Reality (VR) has grown to become state-of-theart technology in many business- and consumer oriented E-Commerce applications. One of the major design challenges of VR environments is the placement of the rendering process. The rendering process converts the abstract description of a scene as contained in an object database to an image. This process is usually done at the client side like in VRML [1] a technology that requires the client’s computational power for smooth rendering. The vision of VR is also strongly connected to the issue of Quality of Service (QoS) as the perceived realism is subject to an interactive frame rate ranging from 10 to 30 frames-per-second (fps), real-time feedback mechanisms and realistic image quality. These requirements overwhelm traditional home computers or even high sophisticated graphical workstations over their limits. Our work therefore introduces an approach for a distributed rendering architecture that gracefully balances the workload between the client and a clusterbased server. We believe that a distributed rendering approach as described in this paper has three major benefits: It reduces the clients workload, it decreases the network traffic and it allows to re-use already rendered scenes

Contributing to VRPN with a new server for haptic devices (ext. version)

This article is an extended version of the poster paper: Cuevas-Rodriguez, M., Gonzalez-Toledo D., Molina-Tanco, L., Reyes-Lecuona A., 2015, November. “Contributing to VRPN with a new server for haptic devices”. In Proceedings of the ACM symposium on Virtual reality software and technology. ACM.http://dx.doi.org/10.1145/2821592.2821639VRPN is a middleware to access Virtual Reality peripherals. VRPN standard distribution supports Geomagic® (formerly Phantom) haptic devices through the now superseded GHOST library. This paper presents VRPN OpenHaptics Server, a contribution to VRPN library that fully reimplements VRPN support of Geomagic Haptic Devices. The implementation is based on the OpenHaptics v3.0 HLAPI layer, which supports all Geomagic Haptic Devices. We present the architecture of the contributed server, a detailed description of the offered API and an analysis of its performance in a set of example scenarios.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Prediction-Based Prefetching for Remote Rendering Streaming in Mobile Virtual Environments

Remote Image-based rendering (IBR) is the most suitable solution for rendering complex 3D scenes on mobile devices, where the server renders the 3D scene and streams the rendered images to the client. However, sending a large number of images is inefficient due to the possible limitations of wireless connections. In this paper, we propose a prefetching scheme at the server side that predicts client movements and hence prefetches the corresponding images. In addition, an event-driven simulator was designed and implemented to evaluate the performance of the proposed scheme. The simulator was used to compare between prediction-based prefetching and prefetching images based on spatial locality. Several experiments were conducted to study the performance with different movement patterns as well as with different virtual environments (VEs). The results have shown that the hit ratio of the prediction-based scheme is greater than the localization scheme in the case of random and circular walk movement patterns by approximately 35% and 17%, respectively. In addition, for a VE with high level of details, the proposed scheme outperforms the localization scheme by approximately 13%. However, for a VE with low level of details the localization based scheme outperforms the proposed scheme by only 5%

Reactive attestation : automatic detection and reaction to software tampering attacks

Anti-tampering is a form of software protection conceived to detect and avoid the execution of tampered programs. tamper detection assesses programs’ integrity with load- or execution-time checks. Avoidance reacts to tampered programs by stopping or rendering them unusable. General purpose reactions (such as halting the execution) stand out like a lighthouse in the code and are quite easy to defeat by an attacker. More sophisticated reactions, which degrade the user experience or the quality of service, are less easy to locate and remove but are too tangled with the program’s business logic, and are thus difficult to automate by a general purpose protection tool. In the present paper, we propose a novel approach to antitampering that (i) fully automatically applies to a target program, (ii) uses Remote Attestation for detection purposes and (iii) adopts a server-side reaction that is difficult to block by an attacker. By means of Client/Server Code Splitting, a crucial part of the program is removed from the client and executed on a remote trusted server in sync with the client. If a client program provides evidences of its integrity, the part moved to the server is executed. Otherwise, a server-side reaction logic may (temporarily or definitely) decide to stop serving it. Therefore, a tampered client application can not continue its execution. We assessed our automatic protection tool on a case study Android application. Experimental results show that all the original and tampered executions are correctly detected, reactions are promptly applied, and execution overhead is on an acceptable level