• Journal of Broadcast Engineering
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• v.25 no.4
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• pp.598-608
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• 2020

In this paper, we propose a color correction technique for images acquired through a multi-view camera system for acquiring a 3D model. It is assumed that the 3D volume is captured indoors, and the position and intensity of the light is constant over time. 8 multi-view cameras are used, and converging toward the center of the space, so even if the lighting is constant, the intensity and angle of light entering each camera may be different. Therefore, a color optimization function is applied to a color correction chart taken from all cameras, and a color conversion matrix defining a relationship between the obtained 8 images is calculated. Using this, the images of all cameras are corrected based on the standard color correction chart. This paper proposed a color correction method to minimize the color difference between cameras when acquiring an image using 8 cameras of 3D objects, and experimentally proved that the color difference between images is reduced when it is restored to a 3D image.

• Journal of Korean Society for Geospatial Information Science
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• v.12 no.3 s.30
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• pp.51-59
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• 2004

In the study, there has been a sharp upward trend in road maintenance cost as the expansion of road networks increases. Running a pavement management system(PMS) is indispensable for efficient and scientific maintenance of the whole road networks with limited maintenance budgets. With a PMS, a maintenance plan should be drawn up after surface conditions are precisely examined and analyzed. The majority of the present PMSs are run by the fact that experts first examine surface conditions on sites, and then enter results into systems. However, considering the actual circumstances of the present time and the increase in paved road hereafter, it is inefficient that experts examine the whole paved roads in person and long-lasting PMSs can not be kept up. As a result, after analyzing the accuracy of 3-D coordinates representing road surfaces that was decided using multi orientation and digital photogrammetry, the average of standard errors turned out to be 0.0427m on the X-axis, 0.0527m on the Y-axis and 0.1539m on the Z-axis. It was found to be good enough to be put to practical use for maps drawn on scales below 1 :1000, which are being currently made and used within the country, and GIS data.

• Journal of Korea Multimedia Society
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• v.20 no.2
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• pp.225-233
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• 2017

Line-laser beams are used for accurate measurement of 3D shape, which is robust to external illumination. For depth measurement, we project a line-laser beam across an object from the face and take an image of the beam on the object surface using a CCD camera at some angle with respect to the face. For shape measurement, we project parallel line-laser beams with narrow line to line distance. When a layer of thin materials attached to a cylinder is long narrow along its circumference, we can measure the shape of the layer with a small number of parallel line beams if we project line beams along the circumference of the cylinder. Measurement of the depth of the attached materials on a line-laser beam is based on the number of pixels between an imaginary line along the imaginary cylinder without the attached materials and the beam line along the materials attached to the cylinder. For this we need to localize the imaginary line in the captured image. In this paper, we model the shape of the line as an ellipse and localize the line with least square estimate. The proposed method results in smaller error (maximum 0.24mm) than a popular 3D depth camera (maximum 1mm).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1C
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• pp.47-55
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• 2003

This paper proposes a composition method of mosaic image from the compressed MPEG-2 video stream, in which the displacement between successive frames according to the camera operation is estimated directly from the information involved in the stream. In the proposed method. the approximated optical flow is constructed from motion vectors of macro blocks, and it is used to determine the parameters of the displacements according to the camera operation associated with pan and tilt. The extracted parameters are used to determine the geometric transform of successive video frames in order to construct a mosaic image. The construction of mosaic uses several blending techniques including the one proposed by Nichols in which an analytic weight is used to determine pixel values. Through the experiment, the blending technique based on analytic weights was superior to the others such as averaging and median-based techniques. It provided more smooth changes in background and made use of instantaneous frame information to construct a mosaic. The mosaic in the paper puts the emphasis on the reduction of computation because it is constructed from the motion vectors included in the compressed video without decoding and recalculating exact optical flows. The constructed mosaic can be used in the retrieval of the compressed video as the representative frame of a shot.

• The KIPS Transactions:PartB
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• v.19B no.2
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• pp.107-112
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• 2012

An active object tracking algorithm using Pan and Tilt camera based in the stepwise application of region and color information from realtime image sequences is proposed. To reduce environment noises in input sequences, Gaussian filtering is performed first. An image is divided into background and objects by using the adaptive Gaussian mixture model. Once the target object is detected, an initial search window close to an object region is set up and color information is extracted from the region. We track moving objects in realtime by using the CAMShift algorithm which enables to trace objects in active camera with the color information. The proper tracking is accomplished by controlling the amount of pan and tilt to be placed the center position of object into the middle of field of view. The experimental results show that the proposed method is more effective than the hand-operated window method.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.2
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• pp.273-292
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• 1998

The purpose of this study was to evaluate marginal fit of four all-ceramic crown systems 1) conventional In-Ceram, 2) copy-milled In-Ceram using Celay system, 3) IPS Empress, 4) OPC(Optimal Pressable Ceramic). All ceramic crowns were made on epoxy dies. The fabricated crowns were sandblasted, cleaned with ultrasonic cleansing, silanated, and cemented with Bistite composite resin cement. the selected marginal areas of the crowns were the labial, lingual, mesial, and distal surface. Each selected area of surface was $0.6{\times}1.6mm$ in dimension. The image of each marginal area was captured to computer files using DT-55 Frame Grabber and light microscope connected CCD camera. The marginal gaps were measured every $70{\mu}m$ using computer image analysis program. The results obtained were summarized as follows : 1. The marginal fit of four all-ceramic crowns were significantly different from each other(p<0.01), and mean marginal fit values obtained were $31.42{\pm}16.52{\mu}m$ in conventional In-Ceram, $55.45{\pm}27.90{\mu}m$ in copy-milled In-Ceram using Celay system, $44.36{\pm}24.59{\mu}m$ in IPS Empress, $47.21{\pm}20.42{\mu}m$ in OPC. 2. In the marginal fit of conventional In-Ceraw and copy-milled In-Ceram crowns using Celay system there was no significant difference between mesiodistal and buccolingual surface, but in the marginal fit of IPS Empress and OPC crowns, there was significant difference between mesiodistal and buccolingual surface(p<0.01). 3. The marginal fit of four kinds of all-ceramic crowns was clinically acceptable.

• Journal of Biomedical Engineering Research
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• v.41 no.5
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• pp.173-178
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• 2020

Remote control intervention surgery robotic system improves treatment effect on cardiovascular patients and reduces X-ray exposure. However, at the time of the first procedure, CT (computerized tomography) and other ultrasound diagnostic equipment should be used because the operator must insert the cannula directly into the patient's leg. Improvements to this have been un-met-needs of hospitals. In this paper, we developed a system that can insert the cannula intuitively and quickly by displaying blood vessels at a glance through the system using smart wearable glasses. The core development method is as follows. In order to project augmented reality onto the surgical image, CT scan angiography image is extracted and processed. In the process, three CT-Markers are used to create a coordinate system of blood vessel images. Additionally, a reference marker is photographed on a single camera to obtain a camera coordinate system. Since the CT marker and the reference marker are in the same position, 3D registration is performed. In the text, a detailed explanation will be given.

• Journal of Internet Computing and Services
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• v.10 no.4
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• pp.25-33
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• 2009

In the paper, we proposed a new system to retrieve 3D wrinkle data based on stereo images. Usually, 3D reconstruction based on stereo images or video is very popular and it is the research focus, which has been applied for culture heritage, building and other scene. The target is object measurement, the scene depth calculation and 3D data obtained. There are several challenges in our research. First, it is hard to take the full information wrinkle images by cameras because of light influence, skin with non-rigid object and camera performance. We design a particular computer vision system to take winkle images with a long length camera lens. Second, it is difficult to get the dense stereo data because of the hard skin texture image segmentation and corner detection. We focus on semi-dense stereo matching algorithm for the wrinkle depth. Compared with the 3D scanner, our system is much cheaper and compared with the physical modeling based method, our system is more flexible with high performance.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.6_1
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• pp.511-518
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• 2012

It is well-known that non-metric digital cameras have to be calibrated for the close-range photogrammetry. But, the self-calibration is still not an easy task because it requires rather a large calibration site of accurate control points, multiple image acquisitions in different positions, and accurate image point measurements that are quite labor-intensive and time-consuming. Based on the premise, this study carried out check point accuracy analysis from self-calibration of different control point designs and photo combinations. The test results showed that the calibration using three photos covering three-dimensional control points produced high accuracy, but control points on a plane could attain the comparable accuracy with four photos including a 90-degree rotated photo. We then compared the target accuracy of on-site self-calibration using flat control points to that of laboratory-self calibration and observed comparable results.

• Journal of Biosystems Engineering
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• v.28 no.1
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• pp.65-76
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• 2003

The analysis of cow body parameters is important to provide some useful information fur cow management and cow evaluation. Present methods give many stresses to cows because they are invasive and constrain cow postures during measurement of body parameters. This study was conducted to develop the stereo vision system fur non-invasive analysis of cow body features. Body feature parameters of 16 heads at two farms(A, B) were measured using scales and nineteen stereo images of them with walking postures were captured under outdoor illumination. In this study, the camera calibration and inverse perspective transformation technique was established fer the stereo vision system. Two calibration results were presented for farm A and fm B, respectively because setup distances from camera to cow were 510 cm at farm A and 630cm at farm B. Calibration error values fer the stereo vision system were within 2 cm for farm A and less than 4.9 cm for farm B. Eleven feature points of cow body were extracted on stereo images interactively and five assistant points were determined by computer program. 3D world coordinates for these 15 points were calculated by computer program and also used for calculation of cow body parameters such as withers height. pelvic arch height. body length. slope body length. chest depth and chest width. Measured errors for body parameters were less than 10% for most cows. For a few cow. measured errors for slope body length and chest width were more than 10% due to searching errors fer their feature points at inside-body positions. Equation for chest girth estimated by chest depth and chest width was presented. Maximum of estimated error fur chest girth was within 10% of real values and mean value of estimated error was 8.2cm. The analysis of cow body parameters using stereo vision system were successful although body shape on the binocular stereo image was distorted due to cow movements.