Thierry Duval

A new adaptive data distribution model for consistency maintenance in collaborative virtual environments

Ensuring that all the users see the same state of a Collaborative Virtual Environment (CVE) at the same time is very important to provide effective collaboration between these users. Absolute consistency is nearly impossible to achieve because it would prejudice the system responsiveness during user interactions. Consequently, existing solutions make a trade-off between consistency and system responsiveness according to their own requirements. We propose a new adaptive data distribution model that is able to dynamically change data distribution according to application requirements, users actions and functions that virtual objects fulfill in the virtual environment. Our solutions can deal with several kinds of requirements imposed by various applications and network constraints. The choice of the data distribution can be made at the object level because all the objects of a virtual environment do not necessarily have the same need for consistency. Finally, we evaluate this model for collaborative scientific data visualization using a client/server architecture and HTTP/HTTPS connections. The results show that our model can minimize both interaction latency and gap in consistency between users, so it enables users to always perform real-time interactions in a consistent CVE.

GASP: from modular programming to distributed execution

We present a generic animation and simulation platform which integrates the different animation models: descriptive, generative and behavioural models. The integration of these models in the same platform offers to each dynamic entity a more realistic and a richer environment, and thereby increases possible interactions between an actor and its environment. Therefore we describe the kernel of the platform, then we explain how it is used from the programmers point of view and we illustrate its use in the field of driving simulation.

Reconfigurable tangible devices for 3D virtual object manipulation by single or multiple users

In this paper we introduce the concept of a Reconfigurable Tangible Device for manipulation of 3D objects in virtual environments by single or multiple users. This Reconfigurable Tangible Device (RTD) provides points of manipulation rigidly linked together. The shape of the RTD can be reconfigured at any time as its arms can be compressed or stretched by users at will. Due to its simple shape the Reconfigurable Tangible Device can be attached to any 3D virtual object. Then, it can fully define the motion of the virtual object in 6 Degrees of Freedom. Two examples of Reconfigurable Tangible Device were developed: one with three points of manipulation (a reconfigurable triangle) and one with four points. We illustrate how these two simple devices can match many different shapes of 3D objects, and in different contexts. Preliminary testing was conducted with the RTD based on three points of manipulation involving a collaborative manipulation task in virtual reality. It produced better subjective appreciation for the RTD compared to more classical 3D collaborative techniques.

An asymmetric 2D Pointer/3D Ray for 3D interaction within collaborative virtual environments

In this paper we present a new metaphor for interaction within Collaborative Virtual Environments (CVE). This metaphor is dedicated to non-immersive or semi-immersive 3D interactions, for which users cannot afford to buy expensive devices neither for 3D visualization of their virtual environment nor for interaction. With these low-cost restrictions, we think that it is more effective to use basic 2D metaphors rather than to try to adapt 3D virtual metaphors which would be more difficult to use because of the poor immersion level offered by such systems. The problem that will arise within a CVE is that it is difficult to make a user aware of the 2D metaphors used by another user, because they are not associated with a 3D virtual object of the shared universe. So our idea is to provide to a user a 3D virtual ray (using ray-casting for object selection) that would act like a 2D pointer on the screen, allowing the user to only control the 2D position of the closest ray end, and calculating the orientation of the ray so that its projection on the screen would always be a point. This way, since the user is controlling a 3D virtual ray, the other users can be made aware of his activity. To test the efficiency of this 2D Pointer / 3D Ray, we have made some experiments making users compare different devices to realize some simple selection and manipulation tasks. The results show that this kind of 2D solution is efficient and allows 3D interaction within Virtual Environments by people who cannot afford expensive immersive hardware. This new metaphor allows more users to collaborate within CVE.

Evaluation of remote collaborative manipulation for scientific data analysis

In the context of scientific data analysis, we propose to compare a remote collaborative manipulation technique with a single user manipulation technique. The manipulation task consists in positioning a clipping plane in order to perform cross-sections of scientific data that show several points of interest located inside these data. For the remote collaborative manipulation, we have chosen to use the 3-hand manipulation technique proposed by Aguerreche et al., which is very suitable with a remote manipulation of a plane. We ran two experiments to compare the two manipulation techniques with some participants located in two different countries. These experiments has shown that the remote collaborative manipulation technique was significantly more efficient than the single user manipulation when the 3 points of interest were far apart inside the scientific data and, consequently, when the manipulation task was more difficult and required more precision. When the 3 points of interest were close together, there was not significant difference between the two manipulation techniques.

Scene graph adapter: an efficient architecture to improve interoperability between 3D formats and 3D applications engines

We present a generic architecture which enables the loading of several 3D formats in most 3D application engines. The purpose of this work is to solve the interoperability issue among 3D formats raised by the multiplicity of formats. We propose a programming interface, the Scene Graph Adapter, that allows mixing several 3D formats in a single application without transcoding. The Scene Graph Adapter is composed of two API; a first one that wraps each 3D format and a second one that wraps rendering engines. Wrappers created thanks to these API can be reused in other applications based on the Scene Graph Adapter. The paper introduces our approach and gives an implementation example.

Improving awareness for 3D virtual collaboration by embedding the features of users’ physical environments and by augmenting interaction tools with cognitive feedback cues

The feeling of presence is essential for efficient interaction within Virtual Environments (VEs). When a user is fully immersed within a VE through a large immersive display system, his/her feeling of presence can be altered because of disturbing interactions with his/her physical environment, such as collision with hardware parts of the system or loss of tracking. This alteration can be avoided by taking into account the physical features of the user as well as those of the system hardware and embedding them in the VE. Moreover, the 3D abstract representation of these physical features can also be useful for collaboration between distant users because they can make a user aware of the physical limitations of the others he/she is collaborating with. In this paper we present how we use the Immersive Interactive Virtual Cabin (IIVC) model to obtain this virtual representation of the user’s physical environment and we illustrate how this representation can be used in a collaborative navigation task in a VE. We also present how we can add 3D representations of 2D interaction tools in order to cope with asymmetrical collaborative configurations, providing 3D cues for a user to understand the actions of the others even if he/she is not fully immersed in the shared VE. Last, we briefly explain how we plan to enhance 3D interaction and collaboration by embedding a symbolic 3D user representation that will give 3D information about his/her posture.

Collaborative exploration of 3D scientific data

This demonstration introduces new ways for exploring Collaborative Virtual Environments (CVE) that contain 3D scientific data sets obtained by simulation. In order to make decisions accordingly to their collective knowledge and understanding of the simulation, the users must collaborate and share experiences and comments. We provide tools to enable a good coordination between the users, and to make each user aware of the activity of others. Each user can navigate within the CVE: change her own position, orientation and scale. Each user can also add annotations within the virtual universe. We propose several 3D layouts for the presentation of the data, associated with different 3D navigation tools. Consequently, the user can explore the data accoording to various parameters such as time or temperature. Last we propose a new 3D interaction tool, called 2D Cursor / 3D Pointer, dedicated to selection and manipulation of 3D objects, and application control. This 2D cursor is associated with a 3D geometry in order to make people aware of the activity of the users who are using this tool.

A survey of plasticity in 3D user interfaces

Plasticity of 3D user interfaces refers to their capabilities to automatically fit to a set of hardware and environmental constraints. This area of research has already been deeply explored in the domain of traditional 2D user interfaces. Besides, during the last decade, interest in 3D user interfaces has grown. Designers find with 3D user interfaces new ways to promote and interact with data, such as e-commerce websites, scientific data visualization, etc. Because of the wide variety of Virtual Reality (VR) and Augmented Reality (AR) applications in terms of hardware, data and target users, there is a real interest in solutions for automatic adaption in order to improve the user experience in any context while reducing the development costs. An adaptation is performed in reaction to different criteria defining a system such as the targeted hardware platform, the users context and the structure and the semantic of the manipulated data. This adaptation can then impact the system in different ways, especially content presentation, interaction techniques modifications and eventually the current distribution of the system across a set of available devices. We present the state of the art about plastic 3D user interfaces. Moreover, we present well known methods in the field of 2D user interfaces that could become relevant for 3D user interfaces. With this survey, we show that current solutions do not meet all plasticity requirements. That is why we propose an action plan to meet these requirements.

Collaborative exploration in a multi-scale shared virtual environment

For the 3DUI 2012 contest, we propose a set of metaphors that enable two users to collaborate to find hidden targets in a 3D virtual environment. They are not allowed to communicate by talking or chatting, but only by interacting with shared virtual objects. We propose three solutions to enable one of the users to help the other one to navigate toward targets: displaying direction arrows, lighting up the path to one target, and remotely moving the second user.