We propose a method of downsizing technique for point sampled data which reduces information amount of three dimensional point cloud data. Our method generates clusters and spiral chain lists. Each chain is consists o...
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ISBN:
(纸本)9788086943862
We propose a method of downsizing technique for point sampled data which reduces information amount of three dimensional point cloud data. Our method generates clusters and spiral chain lists. Each chain is consists of three dimensional points. After that, we adopt a predictive encoding to compress these chain lists. In addition, we show the effectiveness of our method with same experimental results by comparison with one of conventional methods. From these experiments, our method can reduce the information amount coordinate data to 31.7% of original model.
A discrete collision detection algorithm to detect self-collisions between deformable objects is presented, this is built up using a Bounding Volume Hierarchy (BVH) and a Feature-based method. The deformations are rep...
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ISBN:
(纸本)9780769539577
A discrete collision detection algorithm to detect self-collisions between deformable objects is presented, this is built up using a Bounding Volume Hierarchy (BVH) and a Feature-based method. The deformations are represented by the features of the mesh, which are within the bounding volumes and consequently the updating time for the BVH is reduced. The algorithm compares the minimum bounded geometry, the 1-ring, with the other spheres of the hierarchy in order to cull away Bounding Volumes (BV) that are far apart. The 3D objects utilised are surface-based and are deformed by warping, control points of splines, and a mass-spring model.
This paper presents an approach to probabilistic active perception planning for scene modeling in cluttered and realistic environments. When dealing with complex, multi-object scenes with arbitrary object positions, t...
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ISBN:
(纸本)9781424466757
This paper presents an approach to probabilistic active perception planning for scene modeling in cluttered and realistic environments. When dealing with complex, multi-object scenes with arbitrary object positions, the estimation of 6D poses including their expected uncertainties is essential. The scene model keeps track of the probabilistic object hypotheses over several sequencing sensing actions to represent the real object constellation. To improve detection results and to tackle occlusion problems a method for active planning is proposed which reasons about model and state transition uncertainties in continuous and high-dimensional domains. Information theoretic quality criteria are used for sequential decision making to evaluate probability distributions. The probabilistic planner is realized as a partially observable Markov decision process (POMDP). The active perception system for autonomous service robots is evaluated in experiments in a kitchen environment. In 80 test runs the efficiency and satisfactory behavior of the proposed methodology is shown in comparison to a random and a step-aside action selection strategy. The objects are selected from a large database consisting of 100 different household items.
This paper introduces the Auto Terrain Generation System (ATGS), which is based on an Interactive Genetic Algorithm (IGA) that enables non-specialist users to rapidly generate terrains. The motivation for using an IGA...
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ISBN:
(纸本)9781424481262
This paper introduces the Auto Terrain Generation System (ATGS), which is based on an Interactive Genetic Algorithm (IGA) that enables non-specialist users to rapidly generate terrains. The motivation for using an IGA is discussed, existing terrain generation techniques are described and a new approach, based on a fractal terrain engine, is outlined. graphics engines allow terrains to be specified with over 800 floating point parameters, which can overwhelm non-specialist users. These parameters also create a vast search space for auto-terrain generation systems that can complicate procedural techniques. ATGS addresses these issues via interaction with the user, which is implemented in ATGS by a web based user interface that allows users to rapidly indicate terrain preferences. These user preferences are used by a genetic algorithm to explore a multi-dimensional parameter space that satisfies the user's intuition and aesthetics. Proof of concept experiments are outlined, results are presented and future research work is projected.
This paper investigates the problem of geo-localization in GPS challenged urban canyons using only skylines. Our proposed solution takes a sequence of upward facing omnidirectional images and coarse 3D models of citie...
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ISBN:
(纸本)9781424466757
This paper investigates the problem of geo-localization in GPS challenged urban canyons using only skylines. Our proposed solution takes a sequence of upward facing omnidirectional images and coarse 3D models of cities to compute the geo-trajectory. The camera is oriented upwards to capture images of the immediate skyline, which is generally unique and serves as a fingerprint for a specific location in a city. Our goal is to estimate global position by matching skylines extracted from omni-directional images to skyline segments from coarse 3D city models. Under day-time and clear sky conditions, we propose a sky-segmentation algorithm using graph cuts for estimating the geo-location. In cases where the skyline gets affected by partial fog, night-time and occlusions from trees, we propose a shortest path algorithm that computes the location without prior sky detection. We show compelling experimental results for hundreds of images taken in New York, Boston and Tokyo under various weather and lighting conditions (daytime, foggy dawn and night-time).
Fast instance generation is a key requirement in atlas-based registration and other problems that need a large number of atlas instances. This paper describes a new method to represent and construct intensity atlases....
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ISBN:
(纸本)9781424441242
Fast instance generation is a key requirement in atlas-based registration and other problems that need a large number of atlas instances. This paper describes a new method to represent and construct intensity atlases. Both geometry and intensity information are represented using B-spline deformation lattices;intensities are approximated using the multi-level B-spline approximation algorithm during model creation and the parallel computation capability of modern graphics processing units is used to accelerate the process of instance generation. Experiments with distal radius CTs show that, with a coefficients-to-voxels ratio of 0.16, intensities can be approximated up to an average accuracy of 2 +/- 17 grey-levels (out of 3072 total grey-levels), and instances of resolution 256 x 256 x 200 can be produced in a rate of 25 instances per second with a GeForce GTX 285 video card, which is about 500 times performance improvement over the traditional method that uses plain CPU.
The applications of virtual and augmented reality require high performance equipment normally associated with high costs, inaccessible for small organizations and educational institutions. By adding computing power an...
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ISBN:
(纸本)9789048191505
The applications of virtual and augmented reality require high performance equipment normally associated with high costs, inaccessible for small organizations and educational institutions. By adding computing power and storage capacity of several PCs interconnected by a network we have an alternative of high performance and low cost. The objective of this project is to implement an augmented reality platform integrated with items available in the laboratories of an educational institution, such as PCs, webcams, Ethernet networking and free software. This platform is an attractive and economical alternative for the development and implementation of virtual and augmented reality applications to enable low-budget institutions simulate processes, physical phenomena, weather, etc. In this first phase, we have a prototype that creates a scene consisting of a set of virtual objects, the video stream acquired from a Webcam and processes the captured image into a graphic with a set of virtual objects. A user facing the angle of acquisition of the webcam can interact with virtual objects in the scene with only the move of his hand. Although our prototype is reduced to only two computers the first in which images are acquired through the webcam and the second where the mixture, processing and visualization of the scene is made, these early results demonstrate the feasibility of our idea and are a strong motivation for continuing the project. As future work we have planned to increase the number of Webcams, to explore the interaction with complex virtual scenes as well as distributing the processing of the scene among a group of computers to increase the size of the scene displayed.
We introduce a new representation for modeling and rendering plants and trees. The representation is multiresolution and can be automatically generated and rendered in an efficient way. For the trunk and branches we p...
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We introduce a new representation for modeling and rendering plants and trees. The representation is multiresolution and can be automatically generated and rendered in an efficient way. For the trunk and branches we procedurally build a multiresolution structure that preserves the visual appearance of a tree, when rendered at different levels of detail. For the leaves we build a hierarchy of images by pre-processing the botanical tree structure. Unlike other representations, the visual quality of our representation does not depend on viewing position and direction. Our models can be applied to any computer graphics area that requires modeling outdoor scenes like interactive walkthroughs and fly-by's, realistic rendering, simulation and computer games. (C) 2010 Published by Elsevier Ltd.
Most modeling and simulation approaches applied in cell biology assume a homogeneous distribution of particles in space, although experimental studies reveal the importance of space to understand the dynamics of cells...
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ISBN:
(纸本)9781424498642
Most modeling and simulation approaches applied in cell biology assume a homogeneous distribution of particles in space, although experimental studies reveal the importance of space to understand the dynamics of cells. There are already numerous spatial approaches focusing on the simulation of cells. Recently, they have been complemented by a set of spatial modeling languages whose operational semantics are tied partly to existing simulation algorithms. These modeling languages allow an explicit description of spatial phenomena, and facilitate analysis of the temporal spatial dynamics of cells by a clear separation between model, semantics, and simulator. With the supported level of abstraction, each of those offers a different perception of the spatial phenomena under study. In this paper, we give an overview of existing modeling formalisms and discuss some ways of combining approaches to tackle the problem the computational costs induced by spatial dynamics.
We study the watermarking of 2D vector data and introduce a framework which preserves topological properties of the input. Our framework is based on so-called maximum perturbation regions (MPR) of the input vertices, ...
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ISBN:
(纸本)9781424474936
We study the watermarking of 2D vector data and introduce a framework which preserves topological properties of the input. Our framework is based on so-called maximum perturbation regions (MPR) of the input vertices, which is a concept similar to the just-noticeable-difference constraint. The MPRs are computed by means of the Voronoi diagram of the input and allow us to avoid (self-)intersections of input objects that might result from the embedding of the watermark. We demonstrate and analyze the applicability of this new framework by coupling it with a well-known approach to watermarking that is based on Fourier descriptors. However, our framework is general enough such that any robust scheme for the watermarking of vector data can be applied.
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