• Proceedings of the KSME Conference
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• 2003.11a
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• pp.658-663
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• 2003

A process of 3-D stereo particle image velocimetry(PIV)was developed for the measurement of an illuminated sliced section field of 3-D complex flows. The present method includes modeling of camera by a calibrator based on the homogeneous coordinate system, transformation of the oblique-angled image to the right-angled image, identification of 2-D velocity vectors by 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system, removal of error vectors by a statistical method followed by a continuity equation criteria, and finally 3-D display as the post processing. An experimental system was also used for the application of the proposed method. Two high speed digital CCD cameras and an Argon-Ion Laser for the illumination were adopted to clarify the time-dependent characteristics of the leading edge extension(LEX) in a highly swept shape applied to a delta wing found in modern air-fighters.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.524-529
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• 2002

In this paper, we report the development of two DEM (digital elevation model) generation algorithms over urban areas from an IKONOS stereo pair. One ("EpiMatch") is originally developed for SPOT images and modified for IKONOS images. It uses epipolar geometry for accurate DEM generation. The other is based on graph-cut algorithm in 3D voxel space. This algorithm is believed to work better on height discontinuities than EpiMatch. An IKONOS image pair over Taejon city area was used for tests. Using ground control points obtained from differential GPS, camera model was set up and stereo matching applied. As a result, two DEMs over urban areas were produced. Within a DEM from EpiMatch small houses appear as small "cloudy" patches and large apartment and industrial buildings are visually identifiable. Within the DEM from graph-cut we could achieve better height information on building boundaries. The results show that both algorithms can generate DEMs from IKONOS images although more research is required on handling height discontinuities (for "EpiMatch") and on faster computation (for "Graph-cut").

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.19-22
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• 2002

A process of 3-D particle image velocimetry, called here, as '3-D stereo PIV' was developed for the measurement of a section field of 3-D complex flows. The present method includes modeling of camera by a calibrator based on the homogeneous coordinate system, transfromation of oblique-angled image to transformed image, identification of 2-D velocity vectors by 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system and finally 3-D animation as the post processing. In principle, as two frame images only are necessary for the single instantaneous analysis of a section field of 3-D flow, more effective vectors are obtainable contrary to the previous multi-frame vector algorithm. An experimental system was also used for the application of the proposed method. Three analog CCD cameras and an Argon-Ion Laser(300mW) for illumination were adopted to capture the wake flow behind a bluff obstacle.

• IEIE Transactions on Smart Processing and Computing
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• v.6 no.3
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• pp.175-182
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• 2017

In this paper, we present a multi-depth generation method using a time-of-flight (ToF) fusion camera system. Multi-view color cameras in the parallel type and ToF depth sensors are used for 3D scene capturing. Although each ToF depth sensor can measure the depth information of the scene in real-time, it has several problems to overcome. Therefore, after we capture low-resolution depth images by ToF depth sensors, we perform a post-processing to solve the problems. Then, the depth information of the depth sensor is warped to color image positions and used as initial disparity values. In addition, the warped depth data is used to generate a depth-discontinuity map for efficient stereo matching. By applying the stereo matching using belief propagation with the depth-discontinuity map and the initial disparity information, we have obtained more accurate and stable multi-view disparity maps in reduced time.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.603-605
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• 2005

In this paper, we deal with a calibration method for low cost motion capture sensor using PSD (Position Sensitive Detection). The PSD sensor is employed to measure the direction of incident light from moving markers attached to motion body. To calibrate the PSD optical module, a conventional camera calibration algorithm introduced by Tsai. The 3-dimensional positions of the markers are measured by using stereo camera geometry. From the experimental results, the low cost motion capture sensor can be used in a real time system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3721-3737
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• 2015

3D reconstruction based on binocular data is significant to machine vision. In our method, we propose a new and high efficiency 3D reconstruction approach by using a consumer camera aiming to: 1) address the configuration problem of dual camera in the binocular reconstruction system; 2) address stereo matching can hardly be done well problem in both time computing and precision. The kernel feature is firstly proposed in calibration stage to rectify the epipolar. Then, we segment the objects in the camera into background and foreground, for which system obtains the disparity by different method: local window matching and kernel feature-based matching. Extensive experiments demonstrate our proposed algorithm represents accurate 3D model.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.1
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• pp.69-83
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• 2020

Signboards are standardized according to national legislation for the safety of pedestrians and disaster prevention in urban areas. Signboards should be installed according to the standard. However, it is not easy to manage the signboards systematically due to the number of signboards that have been installed for a long time and frequently changing stores. In this study, we proposed a methodology for distinguishing signboards that deviated from the standard. To this end, the signboard was photographed using a stereo camera, and then the three-dimensional coordinates of the signboard were determined from the signboard image to calculate the signboard's horizontal and vertical dimensions to determine the signboard's specifications. In order to determine the interior and relative orientation parameters of the stereo camera, an outdoor three-dimensional building was used as the test field. Then, the image coordinates of four vertices of the signboard were extracted from the signboard image taken from about 15m ~ 22m distance using deep learning. After determining the signboard's three-dimensional coordinates by using the interior and relative orientation parameters of the stereo camera and the image coordinates of the four vertices of the signboard, the horizontal and vertical sizes of the signboard were calculated, resulting in an error of about 2.7cm on average. The specifications for the ten flat-type signboards showed that all of the horizontal sizes were compliant with the specifications, but the vertical sizes exceeded about 36.5cm on average. Through this, it was found that maintenance of flat-type signboards is needed overall.

• The KIPS Transactions:PartB
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• v.10B no.2
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• pp.151-156
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• 2003

The vergence control method is presented for a parallel-axls stereo camera (PASC) using a signal processing technique such as shift, (rotation), and scaling. The PASC is considered as the simplest one of binocular stereo cameras. However, its major limitation lies in the controllability of vergence since its left and right imaging sensors of CCDs are fixed. On the other hand, a horizontal-moving-axis stereo camera (HMASC) with movable imaging sensors is able to control the vergence by moving its CCDs horizontally. In spite of its vergence controllability, there is a major drawback in the implementation because of complicated mechanical structure and the additional cost. To overcome the vergence control problem of the PASC, an operational principle of the HMASC is applied to the PASC. To be specific, without any additional hardware the vergence control problem of the PASC is solved with the signal processing technique. Assuming the virtual displacement between CCD's, a disappearing part of acquired images is removed and the original image site is recovered via interpolation. Experimental results show that the vergence control between stereo images captured by the PASC it possible with an acceptable degradation of the image quality defending on the virtual displacement of CCDs.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.1
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• pp.58-63
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• 2020

This paper proposes the method for improving the localization accuracy of the mobile robot based on the stereo camera. To restore the position information from stereo images obtained by the stereo camera, the corresponding point which corresponds to one pixel on the left image should be found on the right image. For this, there is the general method to search for corresponding point by calculating the similarity of pixel with pixels on the epipolar line. However, there are some disadvantages because all pixels on the epipolar line should be calculated and the similarity is calculated by only pixel value like RGB color space. To make up for this weak point, this paper implements the method to search for the corresponding point simply by calculating the gap of x-coordinate when the feature points, which are extracted by feature extraction and matched by feature matching method, are a pair and located on the same y-coordinate on the left/right image. In addition, the proposed method tries to preserve the number of feature points as much as possible by finding the corresponding points through the conventional algorithm in case of unmatched features. Because the number of the feature points has effect on the accuracy of the localization. The position of the mobile robot is compensated based on 3-D coordinates of the features which are restored by the feature points and corresponding points. As experimental results, by the proposed method, the number of the feature points are increased for compensating the position and the position of the mobile robot can be compensated more than only feature extraction.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.549-552
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• 2005

This paper presents a 3D video content generation technique and system that uses the multi-view images and the depth map. The proposed uses 3-view video and depth inputs from the 3-view video camera and depth camera for the 3D video content production. Each camera is calibrated using Tsai's calibration method, and its parameters are used to rectify multi-view images for the multi-view stereo matching. The depth and disparity maps for the center-view are obtained from both the depth camera and the multi-view stereo matching technique. These two maps are fused to obtain more reliable depth map. Obtained depth map is not only used to insert a virtual object to the scene based on the depth key, but is also used to synthesize virtual viewpoint images. Some preliminary test results are given to show the functionality of the proposed technique.