• Title, Summary, Keyword: Specular

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Specular Reflectance Measurements of Dielectric Plates in Millimeter Frequency Range

  • Kang, Jin-Seob;Kim, Jeong-Hwan;Kang, Kwang Yong;Yoon, Dae Hwan;Park, Sung Won
    • Journal of electromagnetic engineering and science
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    • v.18 no.2
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    • pp.78-87
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    • 2018
  • This paper describes specular reflectance measurements of dielectric plates in three waveguide frequency bands: D-band (110-170 GHz), G-band (140-220 GHz), and J-band (220-325 GHz). The transmit (Tx) part of the proposed specular reflectance measurement system is stationary, while the receive (Rx) part and the material under test (MUT) holder are concentric-rotating with a 2:1 speed ratio for specular reflectance measurements. In specular reflectance measurements, the first step measures the specular reflection coefficients of an MUT and a metal plate on the MUT holder located at the center of the Tx and Rx parts, and the second step calculates the specular reflectance defined by the specular reflection power (i.e., intensity) of the MUT normalized to that of the metal plate. Multiple reflection effects between the Tx and Rx antennas and the MUT on the measured specular reflectance are minimized by averaging out the multiple specular reflectances measured with changing the separation distance between the two antennas by ${\lambda}/8$ intervals. Measurement results of the perpendicular-polarized specular reflectance of commonly used dielectric plates are verified by comparing those with the analytic results and show that the results measured over the overlapped frequency range of the D-/G-bands and at the boundary frequency of the G-/J-bands agree well with the results for the other band, respectively.

Extracting roof edges of specular polyhedra (경면 다면체의 모서리 추출)

  • 박원식;조형석
    • 제어로봇시스템학회:학술대회논문집
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    • pp.379-382
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    • 1997
  • This paper introduces a new vision technique for extracting roof edges of polyhedra having specularly reflecting surfaces. There have been many previous works on object recognition using edge information. But they can not be applied to specular objects since it is hard to acquire reliable camera images of specular objects. If there is a method which can extract the edges of specular objects, it is possible to apply edge-based recognition algorithms to specular objects. To acquire the reliable edge images of specular objects, scanned double pass retroreflection method is proposed, whose main physical characteristic is curvature-sensitive. This utility of the physical characteristic is motivated by the idea that roof edges can be characterized as local surfaces of high curvature. In this paper, the optical characteristics of double pass retroreflection are discussed and a series of simulation studies are performed to verify and analyze the sensor characteristics. The results from a series of simulations show the effectiveness of the proposed method.

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Estimation of the 3-D Shape Surfaces with Specular Reflections

  • Kim, Jee Hong
    • Journal of the Optical Society of Korea
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    • v.18 no.6
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    • pp.672-678
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    • 2014
  • We propose a method to estimate the 3-D shape of surfaces with specular reflection, using a model of the difference in appearance between images reflected from a flat surface and a curved surface. First, we analyze the geometry of spatial reflection from a specular surface and how reflected light varies due to a curved surface. This is used to estimate 3-D shape. The proposed method is shown to be effective in experiments using illumination from spatially distributed light sources and a camera capturing the reflected light from curved, specular surfaces.

Estimation of Specular Light Power by Adjusting Incident Laser Power for Measuring Mirror-Like Surface Roughness (경면 거칠기 측정을 위해 레이저 입사 강도 조정에 의한 정반사 광량 추정 알고리즘 개발)

  • 서영호;김주년;안중환
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.6
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    • pp.94-101
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    • 2004
  • From the Beckmann's reflection model of wave incident, reflected light from a surface is known to have not only specular but also diffuse components. The specular component dominant a surface for a mirror-like surface is distributed on the almost the same area as the spot on the surface, but the diffuse component region dominant f3r a rough surface spreads scattered on the larger areas than the spot. Therefore, statistic parameters from the scattered light distribution are more meaningful in the diffuse region, while the magnitude of rather meaning in the specular region. In usual, there need two sensors to acquire two kinds of information: Photo-detector for light intensity magnitude and image sensor for light intensity distribution. But dual sensor scheme requires a beam splitter usually to feed light to each sensor, and moreover there is not a combination rule to relieve the different sensor characteristics. In this study a new method is proposed for acquisition of the dual information using only an image sensor. Specular region is established on an image area being distinguished from a diffuse component, and laser power is adjusted so that no pixel of the image sensor in the specular region is saturated. Simulation based on the light reflection theory and the experimental results are quite well matched, and thus the proposed method was proved to be very useful for mirror-like surface measurement.

Stylized Specular Reflections Using Projective Textures based on Principal Curvature Analysis (주곡률 해석 기반의 투영 텍스처를 이용한 스타일 반사 효과)

  • Lee, Hwan-Jik;Choi, Jung-Ju
    • Journal of the HCI Society of Korea
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    • v.1 no.1
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    • pp.37-44
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    • 2006
  • Specular reflections provide the visual feedback that describes the material type of an object, its local shape, and lighting environment. In photorealistic rendering, there have been a number of research available to render specular reflections effectively based on a local reflection model. In traditional cel animations and cartoons, specular reflections plays important role in representing artistic intentions for an object and its related environment reflections, so the shapes of highlights are quite stylistic. In this paper, we present a method to render and control stylized specular reflections using projective textures based on principal curvature analysis. Specifying a texture as a pattern of a highlight and projecting the texture on the specular region of a given 3D model, we can obtain a stylized representation of specular reflections. For a given polygonal model, a view point, and a light source, we first find the maximum specular intensity point, and then locate the texture projector along the line parallel to the normal vector and passing through the point. The orientation of the projector is determined by the principal directions at the point. Finally, the size of the projection frustum is determined by the principal curvatures corresponding to the principal directions. The proposed method can control the position, orientation, and size of the specular reflection efficiently by translating the projector along the principal directions, rotating the projector about the normal vector, and scaling the principal curvatures, respectively. The method is be applicable to real-time applications such as cartoon style 3D games. We implement the method by Microsoft DirectX 9.0c SDK and programmable vertex/pixel shaders on Nvidia GeForce FX 7800 graphics subsystems. According to our experimental results, we can render and control the stylized specular reflections for a 3D model of several ten thousands of triangles in real-time.

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Study on the Specular Effect in NiO spin-valve Thin Films (NiO 스핀밸브 박막의 Specular Effect에 의한 자기저항비의 향상에 대한 연구)

  • Choi, Sang-Dae;Joo, Ho-Wan;Lee, Ky-Am
    • Journal of the Korean Magnetics Society
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    • v.12 no.6
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    • pp.231-234
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    • 2002
  • Magnetic properties are investigated for top- and bottom-type spin valves of Si/SiO$_2$/NiO(60nm)/Co(2.5nm)/Cu(1.95nm)/Co(4.5nm)/NOL(t nm; Nano Oxide layer). The MR ratios of the bottom-type spin valves with NOL are larger than those of the top-type spin valves. However, the enhancement of the former is lower than the latter. Both of spin-valves also showed almost constant Ap and smaller p. Enhanced MR ratios of spin valves with NOL result mainly from small values of with constant Ap which due to specular diffusive electron scattering at NOL(NiO)/metal interfaces.

Machinining of Specular Hologram using End-mill Technology (엔드밀 가공을 이용한 스페큘러 홀로그램 제작)

  • Jeon, Eun-Chae;Cha, Jin-Ho;Lee, Je-Ryung;Choi, Hwan-Jin;Kim, Chang-Eui;Je, Tae-Jin;Kim, Hwi;Choi, Doo-Sun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.13 no.4
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    • pp.1-6
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    • 2014
  • The specular hologram is one type of hologram, and it consists of many arcs. They are very easy to fabricate and can even be machined by hand and a compass. In this study, we designed two squares having different depths and consisting of many arcs, after which we machined the arcs using end-mill technology. The width of the machined arcs showed high repeatability. Moving tracks were observed on the bottom surface, and top burrs were noted. In spite of them, the phenomenon of the specular hologram was observed when an observer and a light source stood on the same side. The two squares seemed to have different depths when they were observed from the left and right directions. In this study, it was verified that a specular hologram can be manufactured by end-mill technology.

Image Processing for 3-D Shape Estimation of Specular Reflection (경면반사체의 3차원 형상 추정을 위한 영상처리)

  • Kim, Jee-Hong;Cho, Byung-Gwon
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.49 no.4
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    • pp.1-9
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    • 2012
  • A method to estimate the 3-D shape of surface with specular reflection is proposed, where the difference between the images reflected from a flat surface and a curved surface is used. First, we analyzed the geometry of the spatial reflection at specular surface and the variation of reflected light due to curved surface, whose results are used to estimate 3-D shape. The proposed method is shown to be effective via experiments using the illumination with spatially distributed light source and the CCD camera to capture the light reflected from a surface. In experiments, the captured images from curved surface with specular reflection are processed to approximately estimate 3-D shape.

A curvature profilometry using white-light (백색광을 이용한 곡률 측정법 개발)

  • Kim, Byoung-Chang
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.7 no.3
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    • pp.81-86
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    • 2008
  • I present a 3-D profiler specially devised for the profile measurement of specular surfaces that requires precision shape accuracy up to a few nanometer. A profile is reconstructed from the curvature of a test part of the surface at several locations along a line. The local curvature data are acquired with White-light Scanning Interferometry. Test measurement proves that the proposed profiler is well suited for the specular surface inspection like precision mirror.

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