• The KIPS Transactions:PartB
• /
• 제13B권5호
• /
• pp.499-506
• /
• 2006

This Paper describes a fast and stable camera pose estimation method for real-time augmented reality systems. From the feature tracking results of a marker on a single frame, we estimate the camera rotation matrix and the translation vector. For the camera pose estimation, we use the shape factorization method based on the scaled orthographic Projection model. In the scaled orthographic factorization method, all feature points of an object are assumed roughly at the same distance from the camera, which means the selected reference point and the object shape affect the accuracy of the estimation. This paper proposes a flexible and stable selection method for the reference point. Based on the proposed method, we implemented a video augmentation system that inserts virtual 3D objects into the input video frames. Experimental results showed that the proposed camera pose estimation method is fast and robust relative to the previous methods and it is applicable to various augmented reality applications.

• Journal of the Institute of Convergence Signal Processing
• /
• 제3권2호
• /
• pp.7-14
• /
• 2002

This paper proposes a camera motion estimation technique using special relations of motion vectors of geometrically symmetrical triple points of two consecutive views of single camera. The proposed technique uses camera-induced motion vectors and their relations other than feature points and epioplar constraints. As contrast to the time consuming iterations or numerical methods in the calculation of E-matrix or F-matrix induced by epipolar constraints, the proposed technique calculates camera motion parameters such as panning, tilting, rolling, and zooming at once by applying the proposed linear equation sets to the motion vectors. And by devised background discriminants, it effectively reflects only the background region into the calculation of motion parameters, thus making the calculation more accurate and fast enough to accommodate MPEG-4 requirements. Experimental results on various types of sequences show the validity and the broad applicability of the proposed technique.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• 제34권11C호
• /
• pp.1040-1048
• /
• 2009

This paper proposes an auto flesh tone balance algorithm for the picture that is taken for people. General white balance algorithms bring neutral region into focus. But, other objects can be basis if its spectral reflectance is known. In this paper the basis for white balance is human face. For experiment, first, transfer characteristic of image sensor is analyzed and camera output RGB on average face chromaticity under standard illumination is calculated. Second, Output rate for the image is adjusted to make RGB rate for the face photo area taken under unknown illumination RGB rate that is already calculated. Input tri-stimulus XYZ can be calculated from camera output RGB by camera transfer matrix. And input tri-stimulus XYZ is transformed to standard color space (sRGB) using sRGB transfer matrix. For display, RGB data is encoded as eight-bit data after gamma correction. Algorithm is applied to average face color that is light skin color of Macbeth color chart and average color of various face colors that are actually measured.

• The KIPS Transactions:PartB
• /
• 제10B권5호
• /
• pp.515-520
• /
• 2003

This paper proposes a calibration method from two images. Camera calibration is necessarily required to obtain 3D Information from 2D images. Previous works to accomplish the camera calibration needed the calibration object or required more than three images to calculate the Kruppa equation, however, we use the geometric constraints of parallelism and orthogonality can be easily presented in man-made scenes. The task of it is to obtain intrinsic and extrinsic camera parameters. The intrinsic parameters are evaluated from vanishing points and then the extrinsic parameters which are consisted of rotation matrix and translation vector of the camera are estimated from corresponding points of two views. From the calibrated parameters, we can recover the projection matrices for each view point. These projection matrices are used to recover 3D information of the scene and can be used to visualize new viewpoints.

• Journal of Korea Game Society
• /
• 제7권4호
• /
• pp.63-70
• /
• 2007

Since the fisheye lens has a wide field of view, it can capture the scene and illumination from all directions from far less number of omnidirectional images. Due to these advantages of the omnidirectional camera, it is widely used in surveillance and reconstruction of 3D structure of the scene In this paper, we present a new self-calibration algorithm of omnidirectional camera from uncalibrated images by considering the inlier distribution. First, one parametric non-linear projection model of omnidirectional camera is estimated with the known rotation and translation parameters. After deriving projection model, we can compute an essential matrix of the camera with unknown motions, and then determine the camera information: rotation and translations. The standard deviations are used as a quantitative measure to select a proper inlier set. The experimental results showed that we can achieve a precise estimation of the omnidirectional camera model and extrinsic parameters including rotation and translation.

• 한국HCI학회:학술대회논문집
• /
• 한국HCI학회 2006년도 학술대회 1부
• /
• pp.1222-1227
• /
• 2006

본 연구의 목적은 객체의 형상정보(3D mesh)와 색/질감정보(image)를 이용하여 텍스쳐 맵핑된 고품질의 가상모델을 생성하는데 있다. 3 차원 형상정보에 대응하는 이미지 상의 텍스쳐 좌표 관계를 구하기 위해 오브젝트 좌표계와 카메라 좌표계 사이의 변환행렬, 카메라의 초점거리, 카메라 CCD 와 프레임상의 이미지 사이의 aspect ratio 를 파라미터로 하는 3D-2D 정합을 수행한다. 이러한 3D-2D 정합을 효율적으로 수행하기 위하여, 카메라 내부파라미터 검정단계, 신뢰도가 높은 초기해 설정단계, 비선형 최적화(Newton method) 단계로 접근한다. 또한, 색/질감정보로 이용되는 객체의 이미지는 촬영조건에 의해 스펙큘러(specular)나 이미지 픽셀값의 포화상태(saturation) 등의 결점을 포함한다. 영상내의 스펙큘러 좌표와 3D-2D 정합의 결과를 이용하여 촬영 당시의 광원을 추정하고, 근사화된 빛반사도 함수(BRDF)를 이용하여, 텍스쳐의 픽셀값 변조를 통해 이미지 촬영 당시의 광원효과가 제거된 디퓨즈 텍스쳐를 획득한다. 본 연구에서는 퐁(Phong)의 모델을 근사화한 빛 반사도 함수 모델로 사용하였다.

• Journal of the Institute of Convergence Signal Processing
• /
• 제4권3호
• /
• pp.27-33
• /
• 2003

The image-based 3D modeling is the technique of generating a 3D graphic model from images acquired using cameras. It is being researched as an alternative technique for the expensive 3D scanner. In this paper, we propose the image-based, 3D modeling system using calibrated stereo cameras. The proposed algorithm for rendering, 3D model consists of three steps, camera calibration, 3D reconstruction, and 3D registration step. In the camera calibration step, we estimate the camera matrix for the image aquisition camera. In the 3D reconstruction step, we calculate 3D coordinates using triangulation from corresponding points of the stereo image. In the 3D registration step, we estimate the transformation matrix that transforms individually reconstructed 3D coordinates to the reference coordinate to render the single 3D model. As shown the result, we generated relatively accurate 3D model.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• 제15권8호
• /
• pp.667-677
• /
• 1990

In this paper, optical inplementation of the Hopfield neural network model for two-dimensinal associative memory is described For the real-time processing of two-dimensional images, the commercial LCTVs are used as a memory mask and an input spatical light modulator. A 4-D memory matrix is realized with a 2-D mask of a matrix arrangement and the inner-products between arbitrary input pattern and memory matrix are carried out by using the multifocus hololens. The output image is then electronically thresholded and fed back to the input of the associative memory system by 2-D CCd camera. From the good experimental results for the high error correction capability, the proposed system can be applied to practical pattern recognition and machine vision systems.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• 제7권8호
• /
• pp.1785-1791
• /
• 2003

This paper presents the mosaic method that the video sequence with shift and rotation information after Mellin Transform. The results are used to compute the projection matrix for each image registration. So before registration, we process camera calibration in order to reduce the image warp by camera and then compute the global projection matrix for image registration for reducing errors from rut image to last image. This paper describes the mosaic method that compute duplication and movement information quickly and robust noise using projection matrix on Mellin Transform.

• Proceedings of the Korean Information Science Society Conference
• /
• 한국정보과학회 2005년도 가을 학술발표논문집 Vol.32 No.2 (1)
• /
• pp.688-690
• /
• 2005

본 논문에서는 비디오 프레임에서의 특징점 추출과 3D 객체의 점들간의 상대적인 좌표만을 사용하여 비디오에 가상객 체를 삽입 하는 방법 을 제안한다. 가상객체의 삽입 위치는 사용자가 대응관계를 지정하여 결정한다. 3D 객체의 비디오 삽입을 위한 투사행렬은 POSIT 알고리즘을 사용하여 계산한다. 가상 객체를 삽입 함에 있어 실객체가 가상객체를 가리는 현상을 해결하였다. 본 논문에서 제안한 방법은 특징점과 3D 객체의 점들 간의 상대적인 좌표만 준비된다면 각 비디오프레임의 카메라 행렬을 계산할 수 있고 가상객체의 가려짐을 고려하여 합성할 수 있다.