• Journal of the Korean Society for information Management
• /
• v.16 no.4
• /
• pp.75-94
• /
• 1999

Indexing is a prerequisite function for the information retrieval system in order to retrieve the information of the documents effectively which are saved in database. As a digital data increases in accordance with the development of a computer, the numbers of literatures to be saved in database have also been increased in a large volume. To retrieve such documents of large volume, a lot of system resources and processing time will be required. In this paper, we suggest a advanced indexing method using text partition. This method can retrieve the documents of large volume in short processing time. We applied this suggested indexing method to real information retrieval system, and proved its excellent functions through the demonstration.

• Journal of Korean Society for Geospatial Information Science
• /
• v.15 no.1 s.39
• /
• pp.55-59
• /
• 2007

This study is aimed to acquire the depth information and measure the water volume of reservoir using the robot-ship equipped with GPS and echosounder. Robot-ship is an automatic system for measuring exact depth and bed topography. According to field experiment results, measured water volume by the robot-ship data was not much exceeding 6.8% in comparison with existing water volume data, and it was guessed because of sediments of reservoir bottom. The robot-ship could be used to acquire economically and exactly the water depth and bed topography of reservoirs, dams, rivers and so on.

• Journal of Biomedical Engineering Research
• /
• v.26 no.1
• /
• pp.23-30
• /
• 2005

3D virtual endoscopy has been used as an alternative non-invasive procedure for visualization of hollow organs. However, due to computational complexity, this is a time-consuming procedure. In this paper, we propose a fast volume rendering algorithm based on perspective ray casting for virtual endoscopy. As a pre-processing step, the algorithm divides a volume into hierarchical blocks and classifies them into opaque or transparent blocks. Then, in the first step, we perform ray casting only for sub-sampled pixels on the image plane, and determine their pixel values and depth information. In the next step, by reducing the sub-sampling factor by half, we repeat ray casting for newly added pixels, and their pixel values and depth information are determined. Here, the previously obtained depth information is utilized to reduce the processing time. This step is recursively performed until a full-size rendering image is acquired. Experiments conducted on a PC show that the proposed algorithm can reduce the rendering time by 70- 80% for bronchus and colon endoscopy, compared with the brute-force ray casting scheme. Using the proposed algorithm, interactive volume rendering becomes more realizable in a PC environment without any specific hardware.

• Journal of KIISE:Computer Systems and Theory
• /
• v.27 no.7
• /
• pp.629-638
• /
• 2000

The main difference between mono-volume rendering and multi-volume rendering is data intermixing. In this paper, we first propose a selective rendering method for fast visualizing specific volume according to the surface level and then present data intermixing method for multiple volumes. The selective rendering method is to generate distance transformed volume using a distance transform to determine the minimum distance to the nearest interesting part and then render it. The data intermixing method for multiple volumes is to combine several volumes using intensity weighted intermixing method, opacity weighted intermixing method, opacity weighted intermixing method with depth information and then render it. We show the results of selective rendering of left ventricle and right ventricle generated from EBCT cardiac images and of data intermixing for combining original volume and left ventricular volume or right ventricular volume. Our method offers a visualization technique of specific volume according to the surface level and an acceleration technique using a distance transformed volume and the effective visual output and relation of multiple images using three different intermixing methods in three-dimensional space.

• IEIE Transactions on Smart Processing and Computing
• /
• v.3 no.2
• /
• pp.59-64
• /
• 2014

This paper presents a method for estimating the bounding volume for image-based 3D object reconstruction. The bounding volume of an object is a three-dimensional space where the object is expected to exist, and the size of the bounding volume strongly affects the resolution of the reconstructed geometry. Therefore, the size of a bounding volume should be as small as possible while it encloses an actual object. To this end, the proposed method uses a set of silhouettes of an object and generates a point cloud using a point filter. A bounding volume is then determined as the minimum sphere that encloses the point cloud. The experimental results show that the proposed method generates a bounding volume that encloses an actual object as small as possible.

• Korean Journal of Radiology
• /
• v.20 no.6
• /
• pp.1001-1002
• /
• 2019

• Journal of Korea Game Society
• /
• v.15 no.2
• /
• pp.159-168
• /
• 2015

This paper introduces effective noise removal method for medical ultrasound volume data. Ultrasound volume data need to be filtered because it has a lot of noise. Conventional 2d filtering methods ignore information of adjacent layers and conventional 3d filtering methods are slow or have simple filter that are not efficient for removing noise and also don't equally operate filtering because that don't take into account ultrasound' sampling character. To solve this problem, we introduce method that fast perform in parallel bilateral filtering that is known as good for noise removal and adjust proportionally window size depending on that's position. Experiments compare noise removal and loss of original data among average filtered or biliteral filtered or adaptive biliteral filtered ultrasound volume rendering images. In this way, we can more efficiently and correctly remove noise of ultrasound volume data.

• Journal of Korean Society of Forest Science
• /
• v.99 no.3
• /
• pp.304-311
• /
• 2010

Korea National Forest Inventory System has been adopting different cluster plot design and new equations to estimate growing stock volumes since 2006. These changes have resulted in volume estimations which show some difference from previous ones. This study is to find out the source of such difference. For this, relevant data was collected from 80 plots of 20 cluster samples according to the cluster plot design applied to 4th and 5th National Forest Inventory. Then growing stock volumes were estimated by using current and previous individual tree volume equations respectively. An investigation was made to detect whether such difference in volume estimates was originated from the changes in cluster plot design or from using different volume equations. T-test results showed that the difference from changes in cluster plot design was negligible. Instead, changes in volume equations had statistically significant effects in volume estimation. Since the volume estimation by the 5th National Forest Inventory would bring overestimation by applying different volume equations, all the volume estimations made prior to 2006 would require necessary modifications for international reporting.

• Journal of Korea Game Society
• /
• v.9 no.4
• /
• pp.89-96
• /
• 2009

In general, the size of volume data is large since it has logical 3D structure so it takes long time to manipulate. Much work has been done to improve processing speed of volume data. In this paper, we propose a interlaced scanning volume rendering that reduce computation time by using temporal coherence with minimum loss of image quality. It renders a current frame by reusing information of previous frame. Conventional volume raycasting renders each frame by casting rays on every pixels. On the other hand, our methods divided an image into n-pixel blocks, then it casts a ray on a pixel of a block per each frames. Consequently, it generates an image by accumulating pixel values of previous n frames. The quality of rendered image of our method is better than that of simple screen space subsampling method since it uses afterimage effect of human cognitive system, and it is n-times faster that the previous one.

• Journal of Korea Game Society
• /
• v.12 no.2
• /
• pp.53-62
• /
• 2012

Visualizing a volume dataset with ray-casting which of visualization methods provides high quality image. However it spends too much time for rendering because the size of volume data are huge. Recently, various researches have been proposed to accelerate GPU-based volume rendering to solve these problems. In this paper, we propose an efficient GPU-based empty space skipping to accelerate volume ray-casting using octree traversal. This method creates min-max octree and searches empty space using vertex splitting. It minimizes the bounding polyhedron by eliminating empty space found in the octree traveral step. The rendering results of our method are identical to those of previous GPU-based volume ray-casting, with the advantage of faster run-time because of using minimized bounding polyhedron.