Efficient conservative collision detection for populated virtual worlds

Large virtual worlds, with considerable level of detail are starting to emerge everywhere, from large areas of actual cities to archaeological detailed reconstructions of sites. Populating a virtual world adds an extra touch to the visualization of these worlds, but unfortunately it also brings an extra burden to the system. Several tasks are required when adding animated characters to a virtual world, such as collision detection, path planning and other AI algorithms, rendering of dynamic geometry, amongst others. In here a method for efficient and scalable conservative collision detection, that is able to deal with large scenes and thousands of avatars, is presented. This method does not perform exact collision detection, hence it is conservative. The method is suitable as a basis for path planning algorithms and other AI algorithms where an avatar is often regarded as ’something’ that can be bounded by a cylinder, or a box. The algorithm is capable of dealing with arbitrarily complex 3D worlds, and does not require any a priori knowledge of the geometry

Efficient conservative collision detection for populated virtual worlds

Large virtual worlds, with considerable level of detail are starting to emerge everywhere, from large areas of actual cities to archaeological reconstructions of large sites. Populating a virtual world adds an extra touch to the visualization of these worlds, but unfortunately it also brings an extra burden to the system. Several tasks are required when adding animated characters to a virtual world, such as collision detection, path planning and other AI algorithms, rendering of dynamic geometry, amongst others. In here a method for efficient and scalable conservative collision detection is presented, that is able to deal with large scenes and thousands of avatars. This method does not perform exact collision detection, hence it is conservative. The method is suitable as a basis for path planning algorithms and other AI algorithms where an avatar is often regarded as 'something' that can be bounded by a cylinder, or a box. The algorithm is capable of dealing with arbitrarily complex 3D worlds, and does not require any a priori knowledge of the geometry.ACM Siggraph, EG, GGC

Path planning for complex 3D multilevel environments

The continuous development of graphics hardware is contributing to the creation of 3D virtual worlds with high level of detail, from models of large urban areas, to complete infrastructures, such as residential buildings, stadiums, industrial settings or archaeological sites, to name just a few. Adding virtual humans or avatars adds an extra touch to the visualization providing an enhanced perception of the spaces, namely adding a sense of scale, and enabling simulations of crowds. Path planning for crowds in a meaningful way is still an open research field, particularly when it involves an unknown polygonal 3D world. Extracting the potential paths for navigation in a non automated fashion is no longer a feasible option due to the dimension and complexity of the virtual environments available nowadays. This implies that we must be able to automatically extract information from the geometry of the unknown virtual world to define potential paths, determine accessibilities, and prepare a navigation structure for real time path planning and path finding. A new image based method is proposed that deals with arbitrarily a priori unknown complex virtual worlds, namely those consisting of multilevel passages (e.g. over and below a bridge). The algorithm is capable of extracting all the information required for the actual navigation of avatars, creating a hierarchical data structure to help both high level path planning and low level path finding decisions. The algorithm is image based, hence it is tessellation independent, i.e. the algorithm does not rely on the underlying polygonal structure of the 3D world. Therefore, the number of polygons does not have a significant impact on the performance, and the topology has no weight on the results.Fundação para a Ciência e a Tecnologi

Path planning for complex 3D multilevel environments

The continuous development of graphics hardware is contributing to the creation of 3D virtual worlds with high level of detail, from models of large urban areas, to complete infrastructures, such as residential buildings, stadiums, industrial settings or archaeological sites, to name just a few. Adding virtual humans or avatars adds an extra touch to the visualization providing an enhanced perception of the spaces, namely adding a sense of scale, and enabling simulations of crowds. Path planning for crowds in a meaningful way is still an open research field, particularly when it involves an unknown polygonal 3D world. Extracting the potential paths for navigation in a non automated fashion is no longer a feasible option due to the dimension and complexity of the virtual environments available nowadays. This implies that we must be able to automatically extract information from the geometry of the unknown virtual world to define potential paths, determine accessibilities, and prepare a navigation structure for real time path planning and path finding. A new image based method is proposed that deals with arbitrarily a priori unknown complex virtual worlds, namely those consisting of multilevel passages (e.g. over and below a bridge). The algorithm is capable of extracting all the information required for the actual navigation of avatars, creating a hierarchical data structure to help both high level path planning and low level path finding decisions. The algorithm is image based, hence it is tessellation independent, i.e. the algorithm does not use the underlying polygonal structure of the 3D world. Therefore, the number of polygons as well as the topology, do not affect the performance

A survey of real-time crowd rendering

In this survey we review, classify and compare existing approaches for real-time crowd rendering. We first overview character animation techniques, as they are highly tied to crowd rendering performance, and then we analyze the state of the art in crowd rendering. We discuss different representations for level-of-detail (LoD) rendering of animated characters, including polygon-based, point-based, and image-based techniques, and review different criteria for runtime LoD selection. Besides LoD approaches, we review classic acceleration schemes, such as frustum culling and occlusion culling, and describe how they can be adapted to handle crowds of animated characters. We also discuss specific acceleration techniques for crowd rendering, such as primitive pseudo-instancing, palette skinning, and dynamic key-pose caching, which benefit from current graphics hardware. We also address other factors affecting performance and realism of crowds such as lighting, shadowing, clothing and variability. Finally we provide an exhaustive comparison of the most relevant approaches in the field.Peer ReviewedPostprint (author's final draft

Analysis domain model for shared virtual environments

The field of shared virtual environments, which also encompasses online games and social 3D environments, has a system landscape consisting of multiple solutions that share great functional overlap. However, there is little system interoperability between the different solutions. A shared virtual environment has an associated problem domain that is highly complex raising difficult challenges to the development process, starting with the architectural design of the underlying system. This paper has two main contributions. The first contribution is a broad domain analysis of shared virtual environments, which enables developers to have a better understanding of the whole rather than the part(s). The second contribution is a reference domain model for discussing and describing solutions - the Analysis Domain Model

Scalable collision detection for distributed virtual environments

PhD ThesisDistributed Virtual Environments (DVEs) provide a mechanism whereby dispersed users can interact with one-another within a shared \'irtual world. DVEs commonly allow users to interact with one-another in ways analogous to the real-world, e.g. mimicking Newtonian physics. A scalable DVE should enable large numbers of users to participate simultaneously, regardless of the In geographical location and hardware configurations of individual users. addition, these users should perceive a mutually-consistent virtual world in which each user perceives a consistent series of events in real-time. Collision detection and response is a fundamental requirement of most virtual environments and simulations. It is a computationally-expensive operation which must be perfonned at frequent intervals in all virtual environments which simulate the motion of solid objects. Collision detection has received large amounts of research interest and as a result a number of efficient collision detection algorithms have been proposed. However, these collision detection approaches are designed to detect collisions efficiently in simulations run on a single machine and are not capable of overcoming problems associated with scalability and consistency, which are of paramount importance in DVEs. This thesis presents a new collision detection approach, tenned distributed collision detection, which provides high-levels of scalability, consistency and responsiveness. This thesis presents the algorithms and theory which underpin the distributed collision detection approach and provides experimental results demonstrating its scalability and responsiveness

Virtual Reality Games for Motor Rehabilitation

This paper presents a fuzzy logic based method to track user satisfaction without the need for devices to monitor users physiological conditions. User satisfaction is the key to any product’s acceptance; computer applications and video games provide a unique opportunity to provide a tailored environment for each user to better suit their needs. We have implemented a non-adaptive fuzzy logic model of emotion, based on the emotional component of the Fuzzy Logic Adaptive Model of Emotion (FLAME) proposed by El-Nasr, to estimate player emotion in UnrealTournament 2004. In this paper we describe the implementation of this system and present the results of one of several play tests. Our research contradicts the current literature that suggests physiological measurements are needed. We show that it is possible to use a software only method to estimate user emotion