Visualization of tubular structures such as blood vessels is an important topic in medical imaging. One way to display tubular structures for diagnostic purposes is to generate longitudinal cross-sections in order to ...
详细信息
Visualization of tubular structures such as blood vessels is an important topic in medical imaging. One way to display tubular structures for diagnostic purposes is to generate longitudinal cross-sections in order to show their lumen, wall, and surrounding tissue in a curved plane. This process is called Curved Planar Reformation (CPR). We present three different methods to generate CPR images. A tube-phantom was scanned with comp.ted Tomography (CT) to illustrate the properties of the different CPR methods. Furthermore we introduce enhancements to these methods: thick-CPR, rotating-CPR and multi-path-CPR.
We report on using comp.ted tomography (CT) as a model acquisition tool for comp.ex objects in comp.ter graphics. Unlike other modeling and scanning techniques the comp.exity of the object is irrelevant in CT, which n...
详细信息
We report on using comp.ted tomography (CT) as a model acquisition tool for comp.ex objects in comp.ter graphics. Unlike other modeling and scanning techniques the comp.exity of the object is irrelevant in CT, which naturally enables to model objects with, for example, concavities, holes, twists or fine surface details. Once the data is scanned, one can apply post-processing techniques for data enhancement, modification or presentation. For demonstration purposes we chose to scan a Christmas tree which exhibits high comp.exity which is difficult or even impossible to handle with other techniques. However, care has to be taken to achieve good scanning results with CT. Further, we illustrate post-processing by means of data segmentation and photorealistic as well as non-photorealistic surface and volume rendering techniques.
A PKCS standards support software that could be implemented in a provider and algorithm independent way based on the Java Cryptography Architecture (JCA) and Java Cryptographic Extension (JCE) is outlined. The goal of...
详细信息
A PKCS standards support software that could be implemented in a provider and algorithm independent way based on the Java Cryptography Architecture (JCA) and Java Cryptographic Extension (JCE) is outlined. The goal of JCA/JCE is to provide application independence for particular algorithms and implementations of cryptographic primitives. Improvements of the aliasing scheme provides more efficient reverse mapping of algorithm names to the preferred object identifier (OID).
Scheduling, routing, and layout tasks are examples of hard optimization problems with broad application in industry. Past research in this area has focused on algorithmic issues. However, this approach neglects many i...
详细信息
ISBN:
(纸本)9781581134537
Scheduling, routing, and layout tasks are examples of hard optimization problems with broad application in industry. Past research in this area has focused on algorithmic issues. However, this approach neglects many important human-comp.ter interaction issues that must be addressed to provide people with practical solutions to optimization problems. Automatic methods do not leverage human expertise and can only find solutions that are optimal with regard to an invariably over-simplified problem description. Furthermore, users must understand the generated solutions in order to implement, justify, or modify them. Interactive optimization helps address these issues but has not previously been studied in detail. This paper describes experiments on an interactive optimization system that explore the most appropriate way to combine the respective strengths of people and comp.ters. Our results show that users can successfully identify promising areas of the search space as well as manage the amount of comp.tational effort expended on different subproblems.
In our days the business, scientific and personal databases are growing in an exponential rate. However, what is truly valuable is the knowledge that can be extracted from the stored data. Knowledge Discovery in paten...
详细信息
In our days the business, scientific and personal databases are growing in an exponential rate. However, what is truly valuable is the knowledge that can be extracted from the stored data. Knowledge Discovery in patent databases was traditionally based on manual analysis carried out from statistical experts. Nowadays the increasing interest of many actors have led to the development of new tools for discovering and exploiting information related to technological activities and innovation, "hidden" in patent databases. In this paper we present a system that combines efficient and innovative methodologies and tools for the analysis of patent data stored in international databases and the production of scientific and technological indicators.
The classification of volumetric data sets as well as their rendering algorithms are typically based on the representation of the underlying grid. Grid structures based on a Cartesian lattice are the de-facto standard...
详细信息
The classification of volumetric data sets as well as their rendering algorithms are typically based on the representation of the underlying grid. Grid structures based on a Cartesian lattice are the de-facto standard for regular representations of volumetric data. In this paper we introduce a more general concept of regular grids for the representation of volumetric data. We demonstrate that a specific type of regular lattice - the so-called body-centered cubic - is able to represent the same data set as a Cartesian grid to the same accuracy but with 29.3% fewer samples. This speeds up traditional volume rendering algorithms by the same ratio, which we demonstrate by adopting a splatting implementation for these new lattices. We investigate different filtering methods required for comp.ting the normals on this lattice. The lattice representation results also in lossless comp.ession ratios that are better than previously reported. Although other regular grid structures achieve the same sample efficiency, the body-centered cubic is particularly easy to use. The only assumption necessary is that the underlying volume is isotropic and band-limited - an assumption that is valid for most practical data sets.
In this paper an interactive volume rendering technique is presented which is based on a novel visualization model. We call the basic method "bubble model" since iso-surfaces are rendered as thin semi-transp...
详细信息
In this paper an interactive volume rendering technique is presented which is based on a novel visualization model. We call the basic method "bubble model" since iso-surfaces are rendered as thin semi-transparent membranes similarly to blown soap bubbles. The primary goal is to develop a fast previewing technique for volumetric data which does not require a time-consuming transfer function specification to visualize internal structures. Our approach uses a very simple rendering model controlled by only two parameters. We also present an interactive rotation technique which does not rely on any specialized hardware, therefore it can be widely used even on lowend machines. Due to the interactive display, fine tuning is also supported since the modification of the rendering parameters has an immediate visual feedback.
This paper presents the optical tracking solution developed in the ArcheoGuide project (The Augmented Reality based Cultural Heritage On-site GUIDE, IST-1999-11306). The system enables to recover precisely the user he...
详细信息
ISBN:
(纸本)1581134479
This paper presents the optical tracking solution developed in the ArcheoGuide project (The Augmented Reality based Cultural Heritage On-site GUIDE, IST-1999-11306). The system enables to recover precisely the user head position and orientation at predetermined viewing location without the support of markers. The tracking approach is novel and bases on the real-time registration of the live video-image with so called "reference images" of the site. Once the matching between a live- and a reference-images could have been established, the virtual information can be presented correctly to the user, either using a 2D image warping transformation or after deduction of the current 3D position/orientation of the camera. The image matching algorithm represents the core of the tracking system. It must have real-time performance and be particulary robust to intensity and local changes. We opted for an analysis in frequency space and exploit the invariance properties of the Mellin-Fouricr transform. The tracking system has been tested outdoor in the context of the Archeoguide project. It runs on a laptop at around 10 to 15 Hz and provides views of virtual monuments in a Head Mounted Display superposed to the ruins of the archaeological site.
A new method, based on a height function, to extract the shape of the topological graph of a freeform object was proposed. The proposed method was applied directly on a dense triangulated mesh for calculation of the 3...
详细信息
A new method, based on a height function, to extract the shape of the topological graph of a freeform object was proposed. The proposed method was applied directly on a dense triangulated mesh for calculation of the 3D isocurves and extraction of the topological graph. The comp.tation involved application of the marching cube algorithm, initial value conditions, partial differential equations and Lapalacian equations.
The inner city (Old Town) of Graz will be the European cultural capital in 2003. In this paper we present preliminary results on the reconstruction and visualization of this kind of cultural heritage data. Starting wi...
详细信息
ISBN:
(纸本)1581134479
The inner city (Old Town) of Graz will be the European cultural capital in 2003. In this paper we present preliminary results on the reconstruction and visualization of this kind of cultural heritage data. Starting with a simple block model obtained by converting 2 1/2 dimensional GIS (geographic information system) data we focus on the image based modeling of the facades. Herein we illustrate a robust search for corresponding points to estimate the relative orientation between image pairs. Additional, we outline our real-time rendering approach based on a LOD-R-tree concept. Special attention is paid on the LOD (level of detail) generation for historic buildings where two different ways working in 2D and 3D are explained. The visualization system is communicating asynchronously with a database system storing the LOD-R-tree data structure. This client-server configuration provides interactive navigation through the virtual scene and the scalability of a database management system.
暂无评论