It is well known that both space and the spatial organization play an important role in our work and learning environments as well as in everyday life. There is a definite need for many persons to design their space along with an expert and to preview it in order to test its functionality. Many times there is a need for the inhabitants and workers to collaborate in order to co-design their space from distance. Multi-user 3D virtual environments are a powerful form of collaborative telecommunication applications, enabling the users to share a common three dimensional space and interact with each other as well as with the environment surrounding them, in order to collaboratively solve problems or aid learning processes. This paper presents the work done for extending a multi-user virtual environments platform, to support collaborative spatial design applications. Furthermore, a usage scenario is presented concerning the collaborative design of a classroom for educational purposes. 1.

A distributed virtual environment (DVE) allows geographically separated users to participate in a shared virtual environment via connected networks. However, when the users are connected by the Internet, bandwidth limitation and network latency may seriously affect the performance and the interactivity of the system. This explains why there are very few DVE applications for the Internet. To address these shortcomings, caching and prefetching techniques are usually employed. Unfortunately, the effectiveness of these techniques depends largely on the accuracy of the prediction method used. Although there are a few methods proposed for predicting 3D motion, most of them are primarily designed for predicting the motion of specific objects by assuming certain object motion behaviors. We notice that in desktop DVE applications, such as virtual walkthrough and network gaming, the 2D mouse is still the most popular device used for navigation input. Through studying the motion behavior of a mouse during 3D navigation, we have developed a hybrid motion model for predicting the mouse motion during such navigation—a linear model for prediction at low-velocity motion and an elliptic model for prediction at high-velocity motion. The predicted mouse motion velocity is then mapped to the 3D environment for predicting the user’s 3D motion. We describe how this prediction method can be integrated into the caching and prefetching mechanisms of our DVE prototype. We also demonstrate the effectiveness of the method and the resulting caching and prefetching mechanisms through extensive experiments.

Trimmed NURBS surfaces are often used to model smooth and complex objects. Unfortunately, most existing hardware graphics accelerators cannot render them directly. Although there are a lot of methods proposed to accelerate the rendering of such surfaces, majority of them are based on tessellation, which is developed primarily for handling non-deforming objects. For an object that may deform in run-time, such as clothing, facial expression, human and animal character, the tessellation process will need to be performed repeatedly while the object is deforming. However, as the tessellation process is very time consuming, interactive display of deforming objects is difficult. This explains why deformable objects are rarely used in virtual reality applications. In this paper, we present a efficient method for incremental rendering of deformable trimmed NURBS surfaces. This method can handle both trimmed surface deformation and trimming curve deformation. Experimental results show that our method performs significantly faster than the method used in OpenGL.

An evergreen topic of human-computer interaction research is multi-modality. It has been considered important for the user interface of future computer aided conceptual design systems and what is hoped is that integration of, for instance, voice control, hand gesture/motion processing, and physical object scanning can increase both the semantic level and the efficiency of the interaction. In the area of computer mediated shape conceptualization, especially human hand motion detection and processing can play an important role. The authors' research focuses on the study of the opportunities offered by hand motion processing in shape conceptualization. As a first step they have studied the state of the art and analyzed the technologies applicable to hand motion processing. This paper reports on the findings. The various technologies have been sorted in four categories: direct incomplete, direct complete, indirect incomplete and indirect complete detection. First, the principles supporting this categorization are explained in Section 2. The next four sections of the paper investigate the hand motion detection and processing technologies. Section 7 discusses the characteristics and operational parameters from the aspect of using hand motion for shape input in conceptual design. Our conclusion is that the currently known technologies do not absolutely support processing of a language of hand motions that is under development for creative shape conceptualization. Therefore, the hand motion language needs to be redesigned and adapted to the best technology.

Three dimensional Collaborative Virtual Environments are a powerful form of collaborative telecommunication applications, enabling the users to share a common three-dimensional space and interact with each other as well as with the environment surrounding them, in order to collaboratively solve problems or aid learning processes. Such an environment is “EVE Training Area tool ” which is supported by “EVE platform”. This tool is a three-dimensional space where participants, represented by three-dimensional humanoid avatars, can use a variety of e-collaboration tools. This paper presents advanced functionality that has been integrated on “EVE Training Area tool ” in order to support: (a) multiple collaborative learning techniques (b) Spatial audio conferencing, which is targeted to support principle 3 (augmenting user’s representation and awareness). Furthermore the paper presents technological and implementation issues concerning the evolution of “EVE platform ” in order to support this functionality.