• Journal of Korea Multimedia Society
• /
• v.9 no.2
• /
• pp.234-243
• /
• 2006

The recent rapid development of HCI and surveillance technologies has brought great interests in application systems to process faces. Much of research efforts in these systems has been primarily focused on such areas as face recognition, facial expression analysis and facial feature extraction. However, not many approaches have been reported toward face direction detection. This paper proposes a method to detect the direction of a face using a facial feature called facial triangle, which is formed by two eyebrows and the lower lip. Specifically, based on the single monocular view of the face, the proposed method introduces very simple formulas to estimate the horizontal or vertical rotation angle of the face. The horizontal rotation angle can be calculated by using a ratio between the areas of left and right facial triangles, while the vertical angle can be obtained from a ratio between the base and height of facial triangle. Experimental results showed that our method makes it possible to obtain the horizontal angle within an error tolerance of ${\pm}1.68^{\circ}$, and that it performs better as the magnitude of the vertical rotation angle increases.

• Proceedings of the Korean Information Science Society Conference
• /
• 2000.04b
• /
• pp.625-627
• /
• 2000

최근 실시간 가상 인물 애니메이션 시스템이 활발하게 보급되면서 피부모양을 자연스럽게 유지하면서도 고속으로 동작할 수 있는 인체 변형 방법이 요구되고 있다. 본 논문은 가상 인물을 구성하는 메쉬의 정점들을 회전 연산만으로 이동시켜 실시간에 인체를 변형하는 모델을 제안한다. 인체 변형의 처리과정으로 드로니 삼각화를 이용하여 각 정점의 회전 기준이 될 관절을 찾는 방법을 제시하고, 사원수 형태로 입력된 동작을 회전축의 방향에 따라 분해한 후 각 정점에 차등적으로 적용하여 피부를 자연스럽게 변형할 수 있음을 보인다.

• The KIPS Transactions:PartB
• /
• v.10B no.4
• /
• pp.465-472
• /
• 2003

For an effective pre-treatment process of a face input image, it is necessary to detect each of face components, calculate the face area, and estimate the rotary angle of the face. A proposed method of this study can estimate an robust result under such renditions as some different levels of illumination, variable fate sizes, fate rotation angels, and background color similar to skin color of the face. The first step of the proposed method detects the estimated face area that can be calculated by both adapted skin color Information of the band-wide HSV color coordinate converted from RGB coordinate, and skin color Information using histogram. Using the results of the former processes, we can detect a lip area within an estimated face area. After estimating a rotary angle slope of the lip area along the X axis, the method determines the face shape based on face information. After detecting eyes in face area by matching a partial template which is made with both eyes, we can estimate Y axis rotary angle by calculating the eye´s locations in three dimensional space in the reference of the face area. As a result of the experiment on various face images, the effectuality of proposed algorithm was verified.

• Korean Journal of Optics and Photonics
• /
• v.11 no.1
• /
• pp.19-24
• /
• 2000

Optical transmission characteristics of retardation film for obliquely incident light is calculated by using extended Jones calculus and it is geometrically interpreted on Poincare sphere representation as rotational transformation. The characteristics of a retardation film is that while the rotation axis is fixed at a point on the Equator of the Poincar sphere, the rotation angle varies with the direction of incidence. This property can be compensated by using a tandem arrangement of the two optical films whose optic axes do not coincident, and this method can be used for the improvement of the viewing angle characteristics of BTN cells. cells.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.2
• /
• pp.53-58
• /
• 2022

Since a general household fan has only one left/right turning stage, the rotation angle cannot be adjusted leading to cases whether the wind reaches to an unnecessary area or vice versa. In this paper, we propose a method to efficiently control the turning section to selectively send wind to a necessary space while reducing energy waste. The minimum rotation angle was obtained by experimentally measured the stationary wind direction angle of the fan, and the optimal number of turning stages was selected by appropriately dividing the space where the wind reaches. Through this, it was confirmed that if the fan has a minimum rotation angle of 45°, a turning section of 3 stages and its rotation angle is increased by twice the stationary wind direction angle at each stage, the wind is distributed efficiently. Therefore, it is considered that the selective turning stage control proposed in this paper can minimize energy waste without significant change of the fan structure.

• Proceedings of the Korea Institute of Convergence Signal Processing
• /
• 2005.11a
• /
• pp.155-158
• /
• 2005

MRI 스캔시 화상평면내에서 촬상대상물체의 회전은 MRI 신호에 위상오차와 불균일 표본화를 일으킨다. MRI 신호의 위상오차와 불균일 표본화에 대한 문제의 모델은 화상평면내 임의 중심과 원점에 관한 회전운동에 의해 열화된 MRI 신호들사이에 위상차가 존재함을 나타낸다. 이에 아티팩트가 포함된 MR 화상의 화질을 개선하기위해서 다음과 같은 방법을 제안한다. 우선, 2차원 회전운동의 회전각은 이미 알려져 있고, 회전중심의 위치가 미지인 경우에 대해 위상보정에 기초한 아티팩트를 보정하는 알고리즘과, 다음으로, 회전중심과 각도가 모두 미지인 2차원 회전운동에 대해 아티팩트를 보정하는 알고리즘을 제안한다. 이때, 미지 운동 파라메타를 예측하기위해 촬상대상물체의 경계바깥쪽에서 이상적인 MR 화상의 에너지는 최소가 되고, 촬상대상물체의 회전이 존재할 때 측정된 에너지는 증가한다는 성질을 이용한다. 이러한 성질을 이용해서 각 위상부호화 단계에서 미지의 회전각 크기를 추정하기위한 평가함수가 도입된다. 최종적으로 시뮬레이션 화상 및 실제화상에 적용해서 제안한 본 방법의 유효성을 확인한다.

• Journal of Korea Multimedia Society
• /
• v.15 no.11
• /
• pp.1341-1348
• /
• 2012

In this paper, an efficient scheme for correcting rotated objects in medical images using the Mojette transform is presented. The Mojette transform is a kind of discrete Radon transform, where the transform domain is represented by a set of projections. The Mojette transform currently studied in the image compression area is modified for detecting the rotation angle of objects in medical images. First, in order to find accurate rotation angle, the projection value in the Mojette transform is determined by using pixels on the projection line and in addition the linear interpolation of pixels adjacent to the line. Second, at each projection angle, only one projection is implemented for reducing the amount of the calculation in the process of the Mojette transform. Finally, the projection in the Mojette transform is carried out at the predetermined ROI(Region Of Interest) at which the objects are not cropped or added by rotating the image. The simulation results show that the proposed method has good performance for correcting the rotation angle in medical images.

• Journal of Convergence for Information Technology
• /
• v.11 no.10
• /
• pp.20-26
• /
• 2021

In this paper, we studied the rotation angle estimation methods required for image alignment in an image recognition environment. In particular, a rotation angle estimation method applicable to a low specification embedded-based environment was proposed and compared with the existing method using complex moment. The proposed method estimates the rotation angle through similarity mathcing of the 1D projection profile along the radial axis after converting an image into polar coordinates. In addition, it is also possible to select a method of using vector sum of the projection profile, which more simplifies the calculation. Through experiments conducted on binary pattern images and gray-scale images, it was shown that the estimation error of the proposed method is not significantly different from that of complex moment-based method and requires less computation and system resources. For future expansion, a study on how to match the rotation center in gray-scale images will be needed.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.6
• /
• pp.487-497
• /
• 2011

Numerical analysis has been performed to investigate the rotor speed and pitch range variations when the airspeed is increased in autorotation. Transient Simulation Method(TSM) was used to obtain the steady states of autorotation. The rotor blade was analyzed by the two-dimensional compressible Navier-Stokes solver in order to adapt to the airspeed increase and the results were used in the transient simulation method. Meanwhile, the Pitt/Peters inflow theory was used to supply the induced velocity fields. For the prescribed torque equilibrium state, the combinations of velocity, shaft angle, and pitch angle were produced to investigate the rotor speeds and variable ranges. The rotor tip Mach number and rotor speed were correlated and the trim range of pitch angle was observed with respect to the shaft angle decrease.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2005.05a
• /
• pp.839-842
• /
• 2005

본 논문은 스테레오 카메라를 통해 얻은 변이 정보를 이용하여, 3 차원으로 머리의 회전 각도를 추정하는 방법을 제안한다. 머리 회전에 의한 주시 방향은 사람이 관심을 가지는 방향이므로 이동을 추정하는 것에 비해 많은 중요성을 갖는다. 본 논문에서는 얼굴 영역 내의 여러 특징점들 중 3 개의 특징점들을 포함하는 여러 평면(Plane)이 머리가 이동하더라도, 그 평면들 사이의 각은 변하지 않으므로, 회전 각도 추정에 영향을 주지 않는 점을 이용하여 회전 각도를 추정하였다. 또한, 기존 논문이 카메라 보정을 통해 3 차원 위치를 측정하지만, 제안하는 방법은 변이 공간에서 회전 각도를 추정하기 때문에 카메라 보정 과정이 필요하지 않다. 변이 정보를 얻기 위한 스테레오 장비는 평행 카메라 모델로 가정하며, 얼굴 내의 특징점은 KLT(Kanade-Lucas-Tomasi) 특징 추적 알고리즘을 이용하였다. 실험결과는 기준 영상에 대하여 추정된 3 차원 각도를 나타낸다.