Interprocess data transfer in ATLAS, a platform for distributed applications

The ATLAS platform strives to make several useful but technically involved mechanisms available to the programmer building applications over it with the least possible effort. These mechanisms include network distribution of cooperating processes, a powerful macro language, a journaling system and fault tolerance in the presence of network failures or node crashes. In this paper we discuss the techniques used in ATLAS to implement data transfer over a network between different machines with the least hassle to the programmer.Postprint (published version

On the design and implementation of flexible software platforms to facilitate the development of advanced graphics applications

This thesis presents the design and implementation of a software development platform (ATLAS) which offers some tools and methods to greatly simplify the construction of fairly sophisticated applications. It allows thus programmers to include advanced features in their applications with no or very little extra information and effort. These features include: the splitting of the application in distinct processes that may be distributed over a network; a powerful configuration and scripting language; several tools including an input system to easily construct reasonable interfaces; a flexible journaling mechanism --offering fault-tolerance to crashes of processes or communications--; and other features designed for graphics applications, like a global data identification- --addressing the problem of volatile references and giving support to processes of constraint solving--, and a uniform but flexible view of inputs allowing many different dialogue modes.These can be seen as related or overlapping with CORBA or other systems like Horus or Arjuna, but none of them addresses simultaneously all aspects included in ATLAS; more specifically none of them offers a standardized input model, a configuration and macro language, a journaling mechanism or gives support to processes of constraints solving and parametric design.The contributions of ATLAS are in showing how all these requirements can be addressed together; also in showing means by which this can be attained with little or no performance cost and without imposing on developers the need of mastering all these techniques. Finally, the design of the ATLAS journaling system is to our knowledge original in the simultaneous solution of all of its requirements.Postprint (published version

Automatic code generation for ATLAS communications drivers

ATLAS is a software development platform created in our Department. Among other benefits, it provides support to easily distribute applications over a network. In these applications, communications issues among the different processes should be faced. Pursuing to isolate application developers from the intricacies of these issues, communication drivers are automatically generated from an interface declaration of each process. This automatic code generation --not unlike the generation of stubs in CORBA from the IDL specification-- is the main topic of this report.Postprint (published version

Heterogeneous distribution in ATLAS

The ATLAS platform allows unsophisticated programmers to include advanced features in their applications with no or very little extra information and effort. These features include network distribution of cooperating processes, a powerful macro-language, a flexible journaling system and some other mechanisms directly related to graphics applications problems. In this report we describe how ATLAS is able to distribute the application processes among different architectures without needing a previous configuration information of the available processes for each architecture.Postprint (published version

Enabling collaboration in virtual reality navigators

In this paper we characterize a feature superset for Collaborative Virtual Reality Environments (CVRE), and derive a component framework to transform stand-alone VR navigators into full-fledged multithreaded collaborative environments. The contributions of our approach rely on a cost-effective and extensible technique for loading software components into separate POSIX threads for rendering, user interaction and network communications, and adding a top layer for managing session collaboration. The framework recasts a VR navigator under a distributed peer-to-peer topology for scene and object sharing, using callback hooks for broadcasting remote events and multicamera perspective sharing with avatar interaction. We validate the framework by applying it to our own ALICE VR Navigator. Experimental results show that our approach has good performance in the collaborative inspection of complex models.Postprint (published version

ATLAS, a platform for distributed graphics applications

ATLAS, a platform for developing distributed applications by splitting them into several collaborating processes scattered in a local area network is presented. Although of general use, it has features especially designed for supporting graphics applications. We present its architecture and some aspects of its implementation, and discuss design criteria.Postprint (author’s final draft

Hybrid Rugosity Mesostructures (HRMs) for fast and accurate rendering of fine haptic detail

The haptic rendering of surface mesostructure (fine relief features) in dense triangle meshes requires special structures, equipment, and high sampling rates for detailed perception of rugged models. Low cost approaches render haptic texture at the expense of fidelity of perception. We propose a faster method for surface haptic rendering using image-based Hybrid Rugosity Mesostructures (HRMs), paired maps with per-face heightfield displacements and normal maps, which are layered on top of a much decimated mesh, effectively adding greater surface detail than actually present in the geometry. The haptic probe’s force response algorithm is modulated using the blended HRM coat to render dense surface features at much lower costs. The proposed method solves typical problems at edge crossings, concave foldings and texture transitions. To prove the wellness of the approach, a usability testbed framework was built to measure and compare experimental results of haptic rendering approaches in a common set of specially devised meshes, HRMs, and performance tests. Trial results of user testing evaluations show the goodness of the proposed HRM technique, rendering accurate 3D surface detail at high sampling rates, deriving useful modeling and perception thresholds for this technique.Peer ReviewedPostprint (published version

VR4Health: personalized teaching and learning anatomy using VR

Virtual Reality (VR) is being integrated into many different areas of our lives, from industrial engineering to video-games, and also including teaching and education. We have several examples where VR has been used to engage students and facilitate their 3D spatial understanding, but can VR help also teachers? What are the benefits teachers can obtain on using VR applications? In this paper we present an application (VR4Health) designed to allow students to directly inspect 3D models of several human organs by using Virtual Reality systems. The application is designed to be used in an HMD device autonomously as a self-learning tool and also reports information to teachers in order that he/she becomes aware of what the students do and can redirect his/her work to the concrete necessities of the student. We evaluate both the students’ and the teachers’ perception by doing an experiment and asking them to fill-in a questionnaire at the end of the experiment.This study was partially funded by the Spanish Ministry of Science and Innovation (grant number TIN2017-88515-C2-1-R).Peer ReviewedPostprint (published version

Affordable immersive projection system for 3d interaction

This paper describes an affordable Virtual Reality system designed and developed by a group of researchers at the Polytechnic University of Catalunya (UPC). The system allows direct selection and manipulation of virtual 3D objects. The interaction is based on stereoscopic images projected over the user’s working space and on devices tracking the user’s natural movements. The system includes a screen being adjustable both in orientation and height, sensors tracking the head and hand movements, and a tactile device for the forefinger providing touch sense. A prototype of the system is currently exhibited at the Virtual Reality Center of Barcelona and it is being used in different application fields like architecture, medicine and industrial design.Peer ReviewedPostprint (published version

On extending collaboration in virtual reality environments

We characterize the feature superset of Collaborative Virtual Reality Environments (CVREs) out of existing implementations, and derive a novel component framework for transforming standalone VR tools into full-fledged multithreaded collaborative environments. The contributions of our approach rely on cost-effective techniques for loading graphics rendering, user interaction and network communications software components into separate threads, with a top thread for session collaboration. The framework recasts VR tools under a scalable peer-to-peer topology for scene sharing, callback hooks for event broadcasting and multicamera perspectives of avatar interaction. We validate the framework by applying it to our own Alice VR navigator. Experimental results show good performance of our approach in the collaborative inspection of complex models.Postprint (published version