3,311 research outputs found
Human Motion Trajectory Prediction: A Survey
With growing numbers of intelligent autonomous systems in human environments,
the ability of such systems to perceive, understand and anticipate human
behavior becomes increasingly important. Specifically, predicting future
positions of dynamic agents and planning considering such predictions are key
tasks for self-driving vehicles, service robots and advanced surveillance
systems. This paper provides a survey of human motion trajectory prediction. We
review, analyze and structure a large selection of work from different
communities and propose a taxonomy that categorizes existing methods based on
the motion modeling approach and level of contextual information used. We
provide an overview of the existing datasets and performance metrics. We
discuss limitations of the state of the art and outline directions for further
research.Comment: Submitted to the International Journal of Robotics Research (IJRR),
37 page
PHYSICS-AWARE MODEL SIMPLIFICATION FOR INTERACTIVE VIRTUAL ENVIRONMENTS
Rigid body simulation is an integral part of Virtual Environments (VE) for autonomous planning, training, and design tasks. The underlying physics-based simulation of VE must be accurate and computationally fast enough for the intended application, which unfortunately are conflicting requirements. Two ways to perform fast and high fidelity physics-based simulation are: (1) model simplification, and (2) parallel computation. Model simplification can be used to allow simulation at an interactive rate while introducing an acceptable level of error. Currently, manual model simplification is the most common way of performing simulation speedup but it is time consuming. Hence, in order to reduce the development time of VEs, automated model simplification is needed. The dissertation presents an automated model simplification approach based on geometric reasoning, spatial decomposition, and temporal coherence. Geometric reasoning is used to develop an accessibility based algorithm for removing portions of geometric models that do not play any role in rigid body to rigid body interaction simulation. Removing such inaccessible portions of the interacting rigid body models has no influence on the simulation accuracy but reduces computation time significantly. Spatial decomposition is used to develop a clustering algorithm that reduces the number of fluid pressure computations resulting in significant speedup of rigid body and fluid interaction simulation. Temporal coherence algorithm reuses the computed force values from rigid body to fluid interaction based on the coherence of fluid surrounding the rigid body. The simulations are further sped up by performing computing on graphics processing unit (GPU). The dissertation also presents the issues pertaining to the development of parallel algorithms for rigid body simulations both on multi-core processors and GPU. The developed algorithms have enabled real-time, high fidelity, six degrees of freedom, and time domain simulation of unmanned sea surface vehicles (USSV) and can be used for autonomous motion planning, tele-operation, and learning from demonstration applications
3D Mesh Simplification. A survey of algorithms and CAD model simplification tests
Simpliļ¬cation of highly detailed CAD models is an important step when CAD
models are visualized or by other means utilized in augmented reality applications.
Without simpliļ¬cation, CAD models may cause severe processing and storage is-
sues especially in mobile devices. In addition, simpliļ¬ed models may have other
advantages like better visual clarity or improved reliability when used for visual pose
tracking. The geometry of CAD models is invariably presented in form of a 3D
mesh. In this paper, we survey mesh simpliļ¬cation algorithms in general and focus
especially to algorithms that can be used to simplify CAD models. We test some
commonly known algorithms with real world CAD data and characterize some new
CAD related simpliļ¬cation algorithms that have not been surveyed in previous mesh
simpliļ¬cation reviews.Siirretty Doriast
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
Visualizer: a mesh visualization system using view-dependent refinement
Cataloged from PDF version of article.Arbitrary triangle mesh is a collection of 3D triangles without any shape or boundary restrictions, Progressive mesh (PM) is a multiresolution representation that defines continuous level of detail approximations for arbitrary triangle meshes. PM representation of a mesh can be processed to obtain a mesh approximation between the original and the base (simplified) mesh. Furthermore, PM can be refined in a view-dependent fashion to obtain a simpler mesh within a perceptual image quality. In this paper, we introduce an adaptation and improvements in our implementation for view-dependent refinement of progressive meshes. Essentially, we use a similar approach to Hoppe's framework (ACM Comput. Graphics, Proceedings of SIGGRAPH'97, August 1997, pp. 189-198) for view-dependent refinement with a different algorithm for constructing PM representation. Our method is simple to implement and fast enough to achieve interactive frame rates for moderately complex models (models containing hundreds of thousands of polygons) on a machine with polygon rendering hardware. Moreover, our implementation allows changes to topology and achieves a simpler and sometimes more realistic refinements. (C) 2002 Elsevier Science Ltd. All rights reserved
Learning Behavioural Context
The original publication is available at www.springerlink.co
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A framework for local terrain deformation based on diffusion theory
Terrains have a key role in making outdoor virtual scenes believable and immersive as they form the support for every other natural element in the scene. Although important, terrains are often given limited interactivity in real-time applications. However, in nature, terrains are dynamic and interact with the rest of the environment changing shape on different levels, from tracks left by a person running on a gravel soil (micro-scale), to avalanches on the side of a mountain (macro-scale).
The challenge in representing dynamic terrains correctly is that the soil that forms them is vastly heterogeneous and behaves differently depending on its composition. This heterogeneity introduces difficulties at different levels in dynamic terrains simulations, from modelling the large amount of different elements that compose the oil to simulating their dynamic behaviour.
This work presents a novel framework to simulate multi-material dynamic terrains by taking into account the soil composition and its heterogeneity. In the proposed framework soil information is obtained from a material description map applied to the terrain mesh. This information is used to compute deformations in the area of interaction using a novel mathematical model based on diffusion theory. The deformations are applied to the terrain mesh in different ways depending on the distance of the area of interaction from the camera and the soil material. Deformations away from the camera are simulated by dynamically displacing normals. While deformations in a neighbourhood of the camera are represented by displacing the terrain mesh, which is locally tessellated to better fit the displacement. For gravel based soils the terrain details are added near the camera by reconstructing the meshes of the small rocks from the texture image, thus simulating both micro and macro-structure of the terrain.
The outcome of the framework is a realistic interactive dynamic terrain animation in real-time
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