• 대한전기학회논문지:시스템및제어부문D
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• 제54권3호
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• pp.174-179
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• 2005

This paper presents 3D line segment extraction method, which can be used in generating 3D rooftop model. The core of our method is that 3D line segment is extracted by using line fitting of elevation data on 2D line coordinates of ortho-image. In order to use elevations in line fitting, the elevations should be reliable. To measure the reliability of elevation, in this paper, we employ the concept of self-consistency. We test the effectiveness of the proposed method with a quantitative accuracy analysis using synthetic images generated from Avenches data set of Ascona aerial images. Experimental results indicate that the proposed method shows average 30 line errors of .16 - .30 meters, which are about $10\%$ of the conventional area-based method.

• 한국지구과학회지
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• 제32권6호
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• pp.560-574
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• 2011

주기적이고 지속적으로 자료를 얻을 수 있는 위성영상은 지표면의 변화를 모니터링 하기 위한 매우 효과적인 자료이다. 위성영상을 이용한 기존의 변화탐지 연구는 두 시점의 지표 특성을 각각 분석해 서로 비교하여 변화를 밝혀내는 연구를 주로 해왔다. 그러나 최근에는 연속성을 갖는 다중 시기 위성영상으로부터 전체적인 경향이나 단기적인 변화를 찾아내는 연구에 관심이 높아지고 있다. 이 연구에서는 다중 시기 위성영상을 분석하기 위해 3차원 웨이블릿 변환 기반의 기법을 제안하고 테스트해보았다. 3차원 웨이블릿 변환을 이용하면 자료의 중요한 특성은 보존하면서 차원을 줄이는 것이 가능하다. 또한 다중 시기의 자료로부터 주요 패턴을 간추려 내고 공간, 시간적으로 인접한 주변 화소와의 관계를 파악할 수 있다. 연구 결과, 3차원 웨이블릿 변환 기법은 전체적인 경향성이나 특별한 변화 특성을 빠른 시간내에 밝혀내는 데 유용할 뿐만 아니라 분해 방향에 따라 각기 다른 정보를 제공해 주는 하위 밴드를 통해 새로운 정보를 얻을 수 있을 것으로 기대된다.

• Investigative Magnetic Resonance Imaging
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• 제22권2호
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• pp.86-93
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• 2018

Purpose: Imaging plays a significant role in diagnosing leptomeningeal metastases. However, the most appropriate sequence for the detection of leptomeningeal metastases has yet to be determined. This study compares the efficacies of contrast-enhanced T2 fluid attenuated inversion recovery (FLAIR) and contrast-enhanced 3D T1 black-blood fast spin echo (FSE) imaging for the detection of leptomeningeal metastases. Materials and Methods: Tube phantoms containing varying concentrations of gadobutrol solution were scanned using T2 FLAIR and 3D T1 black-blood FSE. Additionally, 30 patients with leptomeningeal metastases were retrospectively evaluated to compare conspicuous lesions and the extent of leptomeningeal metastases detected by T2 FLAIR and 3D T1 black-blood FSE. Results: The signal intensities of low-concentration gadobutrol solutions (< 0.5 mmol/L) on T2 FLAIR images were higher than in 3D T1 black-blood FSE. The T2 FLAIR sequences exhibited significantly greater visual conspicuity scores than the 3D T1 black-blood sequence in leptomeningeal metastases of the pial membrane of cistern (P = 0.014). T2 FLAIR images exhibited a greater or equal extent (96.7%) of leptomeningeal metastases than 3D T1 black-blood FSE images. Conclusion: Because of its high sensitivity even at low gadolinium concentrations, contrast-enhanced T2 FLAIR images delineated leptomeningeal metastases in a wider territory than 3D T1 black-blood FSE.

• 한국의류학회지
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• 제32권5호
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• pp.800-807
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• 2008

The purpose of this study is to compare the subjective texture of actual objects and their picture images on the Internet to find out a method to present visual images in order to supply information similar real objects. For this study, seven knit fabrics and four presentation methods of visual images including twice magnifications and two dimensions of 2D and 3D. The results of this study were as follows: There are significant differences among subjective textures evaluated by touching seven fabrics actually and we can verify the effects of fiber contents and loop length of knit on textures. We can find out differences of texture depending on presentation methods. In case of 2D evaluation of knits fabrics, visual images of real size present a little exact information on roughness and heaviness whereas those of twice magnification do roughness, wetness, softness and luster. And 3D images give us more exact information of textures on softness, heaviness and warmness, but rather twice enlarged 3D image can't supply an information of heaviness texture.

• 한국측량학회지
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• 제34권2호
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• pp.121-132
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• 2016

This study proposes an approach for simulating high spatial resolution satellite images acquired under arbitrary sun-sensor geometry using existing images and 3D (three-dimensional) data. First, satellite images, having significant differences in spectral regions compared with those in the simulated image were transformed to the same spectral regions as those in simulated image by using the UPDM (Universal Pattern Decomposition Method). Simultaneously, shadows cast by buildings or high features under the new sun position were modeled. Then, pixels that changed from shadow into non-shadow areas and vice versa were simulated on the basis of existing images. Finally, buildings that were viewed under the new sensor position were modeled on the basis of open library-based 3D reconstruction program. An experiment was conducted to simulate WV-3 (WorldView-3) images acquired under two different sun-sensor geometries based on a Pleiades 1A image, an additional WV-3 image, a Landsat image, and 3D building models. The results show that the shapes of the buildings were modeled effectively, although some problems were noted in the simulation of pixels changing from shadows cast by buildings into non-shadow. Additionally, the mean reflectance of the simulated image was quite similar to that of actual images in vegetation and water areas. However, significant gaps between the mean reflectance of simulated and actual images in soil and road areas were noted, which could be attributed to differences in the moisture content.

• 대한원격탐사학회지
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• 제25권3호
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• pp.205-214
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• 2009

This paper investigates stereo 3D viewing for linear pushbroom satellite images using the Orbit-Attitude Model proposed by Kim (2006) and using OpenGL graphic library in Digital Photogrammetry Workstation. 3D viewing is tested with KOMPSAT-2 satellite stereo images, a large number of GCPs (Ground control points) collected by GPS surveying and orbit-attitude sensor model as a rigorous sensor model. Comparison is carried out by two accuracy measurements: the accuracy of orbit-attitude modeling with bundle adjustment and accuracy analysis of errors in x and y parallaxes. This research result will help to understand the nature of 3D objects for high resolution satellite images, and we will be able to measure accurate 3D object space coordinates in virtual or real 3D environment.

• 한국콘텐츠학회논문지
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• 제9권5호
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• pp.13-23
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• 2009

다시점 영상 처리 기술은 다시점 디스플레이 장치와 압축된 데이터 복원 장치를 통해 장치 사용자의 시각에 3차원의 입체 영상을 제공하는데 목적이 있다. 본 논문은 4시점의 병렬 카메라를 통해 실시간으로 입력되는 스테레오 이미지들에 대해서 효율적인 영상 합성을 통해 3차원 입체 영상을 브라우징할 수 있는 램 디스크 기반의 다시점 영상 합성 기법을 제안한다. 제안하는 기법은 입력 영상들을 이진화 영상으로 변환한 후, Sobel 및 Prewitt 에지 발견 알고리즘을 적용시키고 이를 토대로 4개 영상들의 시차를 구한다. 아울러 기존의 알고리즘에서 모호하게 언급되었던 동기화 문제를 해결하기 위해 하드웨어 트리거와 소프트웨어 트리거를 위한 시간 간격을 적용한다. 제안하는 기법을 분산 환경에서도 적용할 수 있도록 영상의 스냅샷에 대한 유일한 식별자를 이용한다. 성능 분석 결과, 전체 영상(왼쪽, 오른쪽) 및 시차정보를 모두 전송하여 고정밀의 3차원 입체 영상을 출력하는 데 소요되는 전체 시간은 각 이진 배열 당 약 0.67초로 실시간으로 적용하는 데 적합하다고 볼 수 있다.

• 복식
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• 제53권5호
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• pp.1-12
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• 2003

This paper proposes a system for measuring the 3D human bodies using the multiple 2D images. The system establishes the multiple image input circumstance from the digital camera for image measurement. The algorithm considering perspective projection leads us to estimate the 3D human bodies from the multiple 2D images such as frontal. side and rear views. The results of the image measurement is compared those of the direct measurement and the 3D scanner for the total 40 items (12 heights, 15 widths and 13 depths). Three persons measure the 40 items using the three measurement methods. In comparison of the results obtained among the measurement methods and the persons, the results between the image measurement and the 3D scanner are very similar. However, the errors for the direct measurement are relatively larger than those between the image measurement and the 3D scanner. For example, the maximum errors between the image measurement and the 3D scanner are 0.41cm in height, 0.39cm in width and 0.95cm in depth. The errors are acceptable in body measurement. Performance of the image measurement is superior to the direct. because the algorithm estimates the 3D positions using the perspective projection. In above comparison, the image measurement is expected as a new method for measuring the 3D body, since it has the various advantages of the direct measurement and 3D scanner in performance for measurement as well as in the devices, cost, Portability and man power.

• Computers and Concrete
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• 제18권3호
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• pp.319-336
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• 2016

In this study, both two- and three-dimensional (2D and 3D) finite-volume-based models were developed to analyze the heat transfer mechanisms through the porous structures of cellular concretes under steady-state heat transfer conditions and to investigate the differences between the 2D and 3D modeling results. The 2D and 3D reconstructed pore networks were generated from the microstructural information measured by 3D images captured by X-ray computerized tomography (X-CT). The computed effective thermal conductivities based on the 2D and 3D calculations performed on the reconstructed porous structures were found to be nearly identical to those evaluated from the 2D cross-sectional images and the 3D X-CT images, respectively. In addition, the 3D computed effective thermal conductivity was found to agree better with the measured values, in comparison with the 2D reconstruction and real cross-sectional images. Finally, the thermal conductivities computed for different reconstructed porous 3D structures of cellular concretes were compared with those obtained from 2D computations performed on 2D reconstructed structures. This comparison revealed the differences between 2D and 3D image-based modeling. A correlation was thus derived between the results of the 3D and 2D models.

• 한국통신학회논문지
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• 제37C권10호
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• pp.859-869
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• 2012

본 논문에서는 3차원 동영상의 시 공간적 정보 중복성 (TSR: temporal-spatial redundancy)과 노블 룩업테이블(N-LUT: novel look-up table)를 이용한 효과적인 3차원 동영상 홀로그램 생성기법인 TSR-N-LUT을 제시하였다. 제안된 기법에서는 먼저, DPCM (differential pulse code modulation) 알고리즘을 이용하여 3차원 동영상 프레임간의 시간적 중복 데이터를 제거한 다음, 잔여 영상에 대해서도 각 프레임별로 영상라인 간 중복 데이터를 제거하게 된다. 따라서, 시 공간적인 중복 데이터가 제거된 물체영상에 N-LUT 기법을 적용함으로써 효과적으로 3차원 비디오 홀로그램을 합성하게 된다. 실험결과 제안된 TSR-N-LUT 기법은 기존 방법에 비해 평균적으로 홀로그램 계산을 위한 물체 포인트 수가 23.72% 감소함과 동시에 홀로그램 생성속도 역시 19.55% 개선됨을 보임으로써 제안된 기법의 실제 응용 가능성을 제시하였다.