HyungSeok Kim

Believability and Interaction in Virtual Worlds

In this paper we present a discussion about believability for Virtual Environments, emotional simulation and also Embodied Conversational Agents (ECAs). We will discuss about the definition of believability and the three elements of believability environments (immersion, presentation and interaction). We also present a discussion about believability and interfaces. Finally, ECA, emotional and personnality simulation are explained and presented.

Adaptation of virtual human animation and representation for MPEG

Abstract While level of detail (LoD) methods for the representation of 3D models are efficient and established tools to manage the trade-off between speed and quality of the rendering, LoD for animation has not yet been intensively studied by the community, and especially virtual humans animation has not been focused in the past. Animation, a major step for immersive and credible virtual environments, involves heavy computations and as such, it needs a control on its complexity to be embedded into real-time systems. Today, it becomes even more critical and necessary to provide such a control with the emergence of powerful new mobile devices and their increasing use for cyberworlds. With the help of suitable middleware solutions, executables are becoming more and more multi-platform. However, the adaptation of content, for various network and terminal capabilities—as well as for different user preferences, is still a key feature that needs to be investigated. It would ensure the adoption of “Multiple Target Devices Single Content” concept for virtual environments, and it would in theory provide the possibility of such virtual worlds in any possible condition without the need for multiple content. It is on this issue that we focus, with a particular emphasis on 3D objects and animation. This paper presents some theoretical and practical methods for adapting a virtual humans representation and animation stream, both for their skeleton-based body animation and their deformation-based facial animation, we also discuss practical details to the integration of our methods into MPEG-21 and MPEG-4 architectures.

Device-based decision-making for adaptation of three-dimensional content

The goal of this research was the creation of an adaptation mechanism for the delivery of three-dimensional content. The adaptation of content, for various network and terminal capabilities – as well as for different user preferences, is a key feature that needs to be investigated. Current state-of-the art research of the adaptation shows promising results for specific tasks and limited types of content, but is still not well-suited for massive heterogeneous environments. In this research, we present a method for transmitting adapted three-dimensional content to multiple target devices. This paper presents some theoretical and practical methods for adapting three-dimensional content, which includes shapes and animation. We also discuss practical details of the integration of our methods into MPEG-21 and MPEG-4 architectures.

Generating unified model for dressed virtual humans

Scenes with crowds of dressed virtual humans are getting more attention and importance in 3D games and virtual reality applications. Crowd scenes, which include huge amounts of virtual humans, require complex computation for animation and rendering. In this research, new methods are proposed to generate efficient virtual human models by unifying a body and a garment into an animatable model, which has skinning parameters for the common skeleton-driven animation. The generated model has controlled complexity in geometry and semantic information. The unified model is constructed by using the correspondence between the body and the garment meshes. To establish the correspondence, two opposite optimization methods are proposed and compared: the first is to fit the body onto the garment and the second is to fit the garment onto the body. The innovative aspect of our method lies in supporting multiple correspondences between body and cloth parts. This enables us to handle the skirt model which is difficult to be processed by using previous works, due to its topological differences to the body model.

Adaptation mechanism for three dimensional content within the MPEG-21 framework

The goal of the research is creation of an adaptation mechanism for the delivery of three-dimensional content. The adaptation of content, for various network and terminal capabilities - as well as for different user preferences, is a key feature that needs to be investigated. Current state-of-the art research of the adaptation shows promising results for specific purpose and limited types of content but still it is not well adaptable for the massive heterogeneous environments. We present a method for transmitting adapted thee-dimensional contents to multiple target devices. We present some theoretical and practical methods for adapting three-dimensional contents, which includes shapes and animation. We also discuss practical details to the integration of our methods into MPEG-21 and MPEG-4 architectures

Multi-resolution meshes for multiple target, single content adaptation within the MPEG-21 framework

To present three-dimensional data both in heavy and light-weight clients, an adaptation scheme is required. Current state-of-the art research shows promising results for specific purposes but it is still not well adoptable for light-weight clients such as mobile devices. In this research, we present a method for transmitting adapted 3D content to multiple target devices. To accomplish this goal, we devised a clustered representation of a multi-resolution model that is flexible, simple, efficient, and works with the MPEG-21 adaptation mechanism.

Visibility Preprocessing for Complex 3D Scenes using Hardware-Visibility Queries

In cases of densely occluded urban scenes, it is useful to determine the visibility of scenes, since only small parts of the scene are visible from a given cell. In this paper, we introduce a new visibility preprocessing method that efficiently computes potentially visible objects for volumetric cells. The proposed method deals with general 3D polygonal models and invisible objects jointly blocked by multiple occluders. The proposed approach decomposes volume visibility into a set of point visibilities, and then computes point visibility using hardware-visibility queries. We carry out experiments on various large-scale scenes, and show the performance of our algorithm. Our performance analysis approach estimates the exact solution of volume visibility. From differences between the estimated solution and the proposed algorithms solution, we show that our algorithm seeks a tight overestimate of the potentially visible set (PVS).

Visibility preprocessing for complex 3D scenes using hardware-visibility queries

In cases of densely occluded urban scenes, it is effective to determine the visibility of scenes, since only small parts of the scene are visible from a given cell. In this paper, we introduce a new visibility preprocessing method that efficiently computes potentially visible objects for volumetric cells. The proposed method deals with general 3D polygonal models and invisible objects jointly blocked by multiple occluders. The proposed approach decomposes volume visibility into a set of point visibilities, and then computes point visibility using hardware-visibility queries, in particular HP-occlusion-test and NV-occlusion-query. We carry out experiments on various large-scale scenes, and show the performance of our algorithm.