Wyniki wyszukiwania - BazTech

1

HIST - an application for segmentation of hepatic images

Reska D., Krętowski M.

Zeszyty Naukowe Politechniki Białostockiej. Informatyka

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2011

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Z. 7

71-93

EN

HIST (Hepatic Image Segmentation Tool) is a Java-based application for segmentation and visualisation of medical images, specialised for hepatic image analysis. This paper contains an overview of the application features, a description of adapted segmentation algorithms and their experimental validation. The application provides two main segmentation methods, based on region growing and active contour model methods, adapted for the case of liver segmentation. HIST also offers data visualisation tools, including multiplanar reconstruction, volume rendering and isosurface extraction.

PL

HIST (ang. Hepatic Image Segmentation Tool – narzędzie do segmentacji obrazów wątroby) jest napisaną w języku Java aplikacją do segmentacji i wizualizacji obrazów medycznych, wyspecjalizowaną segmentacji w obrazów wątroby. Artykuł ten zawiera przegląd możliwości aplikacji, opis zaadaptowanych algorytmów segmentacji i wizualizacji oraz ich eksperymentalną walidację. Aplikacja oferuje dwie główne metody segmentacji, oparte o algorytmy rozrostu regionów i aktywnego konturu, dostosowane do segmentacji wątroby. Narzędzia wizualizacyjne aplikacji wykorzystają rekonstrukcję multiplanarną, rendering wolumetryczny oraz ekstrakcję izopowierzchni.

2

Klasyfikacja i wizualizacja zobrazowań dpTK w środowisku trójwymiarowym

Ogiela M. R., Hachaj T.

Pomiary Automatyka Kontrola

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2011

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R. 57, nr 11

1444-1447

PL

W artykule został zaprezentowany wspomagany sprzętowo algorytm wizualizujący trójwymiarowe dyskretne pola skalarne o teoretycznie dowolnych rozmiarach. Zostały również przedstawione oryginalne wyniki badań, w których określono zależność pomiędzy szybkością wizualizacji (fps) a ilością przesłań danych pomiędzy pamięcią RAM komputera i kartą graficzną. Zbadano także w jaki sposób szacowanie gradientu pola skalarnego przed procesem wizualizacji wpływa na przyspieszenie tworzenia grafiki w wypadku dużych objętości. Jeżeli zbiór danych został podzielony na wiele podzbiorów (w przeprowadzany doświadczeniu było ich 512) algorytmy estymujące gradient we wstępnym przetwarzaniu działały wolniej niż liczące go czasie rzeczywistym, ponieważ te drugie redukują ilość danych, które muszą być przesłane do GPU.

EN

In this paper a new hardware accelerated algorithm pipeline (Fig. 1) for visualization of three-dimensional scalar fields without limitation on dataset size (Fig. 2) is described. There are presented original results of research on average performance speed (fps) of rendering algorithms as a function of data transitions between RAM and GPU (Tab 1. and Fig. 3). The speed of rendering decreases with number of partitioning and view-aligned slices. It has also been investigated how the pre-rendering gradient estimation influences the visualization process in case of large volumetric datasets. It is shown that in case of large partitioning of volume it is better to transfer less data to GPU memory and to compute the gradient value on the fly. The potential usage of that algorithm as a visualization module for the system performing cognitive analysis of dpCT data [3, 4, 5] is presented. The output data of the diagnostic algorithm is a superimposition onto the volume CT data (Fig. 4). This particular solution gives additional support to medical personnel by supplying them with simultaneous visualization of medical data of different modalities enabling more accurate diagnosis.

3

Wizualizacja trójwymiarowych pól skalarnych z wykorzystaniem technik renderingu objętościowego

Głowacki M., Czubernat A.

Czasopismo Techniczne. Mechanika

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2011

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R. 108, z. 4-M/1

147-155

PL

W artykule przedstawiono wyniki badań związanych z opracowaniem i implementacją algorytmu renderingu objętościowego, który umożliwia uzyskanie obrazów trójwymiarowych pól skalarnych w czasie rzeczywistym. Zbudowany system komputerowy wyposażony został w interaktywny interfejs użytkownika oraz narzędzia pozwalające na swobodną manipulację wyświetlanymi danymi. Aplikacja realizuje główne założenia dzięki użyciu akceleracji sprzętowej oferowanej przez programowalne układy graficzne. Obraz generowany jest z wykorzystaniem masywnej równoległości, co pozwala na jego wyświetlanie w czasie rzeczywistym oraz stosowanie technik kosztownych obliczeniowo. Zastosowane metody i ich optymalizacje umożliwiają intuicyjną oraz efektywną analizę danych wolumetrycznych.

EN

The paper deals with development and implementation of volume rendering algorithm that allows the creation of images of three-dimensional scalar fields in real time. The developed computer system is equipped with an interactive user interface and tools allowing for the free manipulation of displayed data. The application executes main objectives through the use of hardware acceleration provided by programmable graphics chips. Image is generated using the massive parallelism, which allows to display it in real time and the use of computationally expensive techniques. The methods used and their optimizations enable an intuitive and efficient analysis of volumetric data.

4

Exploring the Infinite-Time Behavior of the Chaos Game : Approximation and Interactive Visualization of 3D IFSP and RIFS Invariant Measures Using PC Graphics Accelerators

Martyn T.

Machine Graphics and Vision

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2009

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Vol. 18, No. 4

453-476

EN

In this paper we tackle the problem of approximation and visualization of invariant measures arising from Iterated Function Systems with Probabilities (IFSP) and Recurrent Iterated Function Systems (RIFS) on R³. The measures are generated during the evolution of a stochastic dynamical system, which is a random process commonly known as the chaos game. From the dynamical system viewpoint, an invariant measure gives a temporal information on the long-term behavior of the chaos game related to a given IFSP or RIFS. The non-negative number that the measure takes on for a given subset of space says how often the dynamical system visits that subset during the temporal evolution of the system as time tends to infinity. In order to approximate the measures, we propose a method of measure instancing that can be considered an analogue of object instancing for IFS attractors. Although the IFSP and RIFS invariant measures are generated by the long-term behavior of stochastic dynamical systems, measure instancing makes it possible to compute the value that the measure takes on for a given subset of space in a deterministic way at any accuracy required. To visualize the data obtained with the algorithm, we use direct volume rendering. To incorporate the global structure of invariant measures along with their local properties in an image, a modification of a shading model based on varying density emitters is used. We adapt the model to match the fractal measure context. Then we show how to implement the model on commodity graphics hardware using an approach that combines GPU-based direct volume raycasting and 3D texture slicing used in the object-aligned manner. By means of the presented techniques, visual exploration of 3D IFSP and RIFS measures can be carried out efficiently at interactive frame rates.

5

Visualization of 3-D objects in medicine - selected technical aspects for physicians

Lewandowski P., Tomczyk A., Szczepaniak P. S.

Journal of Medical Informatics & Technologies

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2007

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Vol. 11

59--67

EN

In the paper, selected visualization methods are described such as: surface rendering, volume rendering and the simplest approach basing on texture mapping. This work, however, does not aim at a detailed description of those methods but at a friendly presentation of possible ways of visualization and their features which can be of importance for a physician who has some expectations or needs, such as gaining insight into a 3-D object. Those expectations can be satisfied for example by making incisions or using surface transparency option which significantly improves visualization effect and can be of use in diagnostic process.

6

Cumulus cloud synthetic rendering techniques and their evaluations

Maskey M., Newman T. S.

Machine Graphics and Vision

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2005

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Vol. 14, No. 4

399-425

EN

Three new techniques for synthesizing realistic renderings of cumulus clouds are introduced and evaluated. The techniques utilize variations of the Perlin Noise and Koch fractals to achieve a reasonable cloud-like shape and texture. To evaluate the quality of renderings produced by the techniques, three classes of texture features are considered using cluster quality measures. Rendering quality is also evaluated versus real images using shape and texture features.

7

PCRT3D: an interactive three-dimensional radiation treatment planning system based on volume rendering for low-end platforms

Cerezo E., Seron F. J., Soria A.

Machine Graphics and Vision

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1998

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Vol. 7, No. 4

859-878

EN

The objactive of radiation therapy is to concentrate a perscribed radiation dose accurately within a target volume in the patient. Computer assisted radiation treatment planning provides a tool to find the optimum configuration of radiation beams for the treatment of an individual patient. It involves interesting 3D technoques that demand high-end visualisation and computational abilities, pushing the limits of available technology. PCRT3D is a therapy-planning tool that runs under WINDOWS NT and is an updated and improved version of the PCRTv3.2 tool that is being used in more that 30 Spanish hospitals. All the visualisation part of the application has been developed in the Advanced Computer Graphics Group of the University of Zaragoza (Spain). Based on volume rendering, anatonical and dose information can be mixed and observed in 3D and on every desired plane. Some of its major features are a simple and intuitive interface, strict manipulation of the input data coming from the scanner to avoid artifacts showing up and special render algorithms to achieve interactivity. The creation of new images by means of morphing between images, beam-aye-view and digitally reconstructed radiographs also figure among its capabilities.

8

Interactive volume rotation

Csebfalvi B., Szirmay-Kalos L.

Machine Graphics and Vision

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1998

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Vol. 7, No. 4

793-806

EN

In this paper a new volume rendering method is presented which provides real-time rotation without using any acceleration hardware. The algorithm is based on the efficient handling of empty voxels, where according to the opacity values a 3D binary mask is generated indicating the locations of the non-transparent voxels. Ray casting is performed on this binary mask which is rotated rapidly by shear-warp factorization and an incremential aligment technique. The location of non-zero bit hit by a ray is mapped onto the corresponding voxel location in the orginal classified volume, in order to get the opacity and color values in the given samples point. The technique proposed for rotating and sampling the binary mask exploits only the standard ALU operations providing interactive frame rates even on low cost machines.