Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/11

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Department: search.filters.department.İzmir Institute of Technology. Electrical and Electronics EngineeringInstitution Author: search.filters.institutionAuthor.Gümüştekin, Şevket

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Now showing 1 - 10 of 17
  • Conference Object
    Citation - WoS: 2
    Citation - Scopus: 4
    Tek Kamera ve Aynalar Kullanan Bir Görsel Denetleme Sistemi
    (Institute of Electrical and Electronics Engineers Inc., 2004) Gümüştekin, Şevket
    In this paper the geometrical properties of an imaging system are investigated. This system uses mirrors to simulate additional cameras. The geometry developed here helps us to capture the images of an object from meaningful viewpoint locations. The imaging system with the desired geometry is realized by adjusting the positions and orientations of mirrors. A special calibration pattern is used for the process of camera calibration which finds the unknown camera parameters and gives feedback about the degree of compliance with the desired geometry. The calibrated camera and its mirror images are used to create a 2D image of an object surface with a uniform geometry. After a pre-defined inner or outer surface of a test object is imaged from different view angles using mirrors, these images are warped and blended in a single image which is used for visual inspection. Hence, the vaguely defined process of inspecting 3D objects and their surface textures is converted to an efficient and well defined process of inspecting 2D images.
  • Conference Object
    Citation - Scopus: 1
    Hava Fotoğraflarından Deniz Kıyılarının Belirlenmesi
    (Institute of Electrical and Electronics Engineers Inc., 2006) Kahraman, Metin; Gümüştekin, Şevket
    The unique structures of different coastline segments provide distinctive image features for several applications such as oceanography, georeferencing, cartography and autonomous navigation. In this paper, a procedure involving automatic multiresolution coastline extraction is described. Using this method, sea and land textures are segmented utilizing cooccurrence and histogram features of wavelet image representation. The coastlines are identified as the boundaries of the sea regions.
  • Conference Object
    H264/avc ile Sıkıştırılmış Videoda Sahne Değişimi Kestirimi için Bir Yaklaşım
    (Institute of Electrical and Electronics Engineers Inc., 2007) Şimşek, Gökhan; Gümüştekin, Şevket
    In this paper, we provide methods to detect abrupt and gradual scene changes on ISO/ITU H264/AVC coded video sequence using macro-block type information. The analysis is realized in compressed domain without the need of full decompression to pixel domain. In order to realize the proposed methods, several video test sequences are constructed in QCIF resolution. The syntax and semantics, parsing, decoding processes of ISO/ITU H264/AVC is followed to realize such analysis and proposed methods are realized using reference software. The application addresses emerging standard ISO/ITU H264/AVC coded video databases as low level tools to realize a video summarization, abstraction or segmentation system.
  • Conference Object
    Detection of Urban Change Using Remote Sensing and Gis: Izmir Case
    (Taylor and Francis Ltd., 2008) Tarhan, Çiğdem; Arkon, Cemal; Çelik, M.; Gümüştekin, Şevket; Tecim, V.
    This study is an example of how land use changes could be detected via high resolution remotely sensed data. In order to perform "change detection" IKONOS satellite images, belonging to 2001 and 2004, have been used. An automated Graphical User Interface (GUI) has been created for detection of environment. Different image enhancement techniques and a fuzzy inference system have been combined in the GUI. The detection results are classified according to some basic levels such as 20-50% and 70%. Additionally, four different change detection algorithms have been applied which are pixel-based, object based, feature based. These algorithms have been examined according to change detection levels with different image enhancement techniques. At the end of the study, the results have been compared.
  • Conference Object
    Citation - WoS: 2
    Citation - Scopus: 2
    Çok Bakışlı 3b Geriçatımın Polarizasyon Görüntüleme Kullanımıyla İyileştirilmesi
    (Institute of Electrical and Electronics Engineers Inc., 2014) Ozan, Şükrü; Gümüştekin, Şevket
    Performance of stereo imaging methods, which are used to find depth information of a scene, can be adversely affected by surface reflection properties of subjects in the scene and possible change in relative camera and light source positions. In this study a catadioptric multiview imaging system, which is constructed by using planar mirrors, is proposed. Stereo matching problems which are caused by the specular reflections in the scene are highlighted and it is shown that those problems can be significantly alleviated by using polarization images.
  • Conference Object
    Yapısal Aydınlatma Kullanarak Yüzeylerin Geometrik ve Yansıtıcılık Özelliklerinin Geri Çatımı
    (Institute of Electrical and Electronics Engineers Inc., 2015) Ozan, Şükrü; Gümüştekin, Şevket
    It is not possible to perform a robust and dense surface reconstruction for plain colored surfaces which have insufficient surface features, and for surfaces which have specularity effect because of the material nature by using traditional stereo imaging methods. The proposed surface scanner system in this work makes it possible to get a robust and dense surface reconstruction even for plain colored and/or semi glossy surfaces. Reflection properties of the surface material are also reconstructed to some extent by using the information gathered after scanning process. Moreover, the experimental results are shown.
  • Conference Object
    Citation - Scopus: 3
    Sahne Aydınlatmasında Kullanılan Işık Kaynağının Renklilik Değerlerinin Tek İmge Kullanılarak Kestirimi
    (IEEE, 2011) Ozan, Şükrü; Gümüştekin, Şevket
    In this study, main goal is to estimate scene illuminant chromaticity values for each of the three color channels (red, green, blue). It is found that analysis of the pixel values, which are expressed by dichromatic reflection and inverse-intensity chromaticity space definitions, with appropriate statistical methods gives aproximate values for light source chromaticity within an acceptable error range. Single image of a scene is sufficient for calculations. We saw that chromaticity values of light sources with different colors can be approximately calculated. © 2011 IEEE.
  • Conference Object
    Modifiye Bitüm Görüntülerinde Gabor Öznitelikleri ile Doku Analizi
    (Institute of Electrical and Electronics Engineers Inc., 2008) Gümüştekin, Şevket; Topal, Ali; Şengöz, Burak
    İnşaat sanayinde, özellikle ulaşım uygulamalarının vazgerçilmez bir malzemesi olan bütün, gelişmekte olan malzeme teknolojilerinin de katkısı ile daha dayanıklı ve giivenilir yol ve yapıların yapılabilmesi için öncelikli bir araştırma konusu olmuştur. Çeşitli polimer katkı maddelerinin bitüme eklenmesi standart bir uygulama haline gelmiştir. Yapım sırasında kalite kontrolünün sağlanması ve denetlenmesi için modifiye bitümlerin test edilmesi büyük önem taşımaktadır. Bu çalışmada mekanik yöntemlere alternatif olan yeni bir yöntem sunulmuştur. Gabor öznitelikleri kullanılarak modifiye bitiim gorüntülerinin dokusal özellikleri incelenmiş; bitüme eklenen katkı maddelerinin ve bu maddelerin hangi oranda eklendiğinin algılanmasınzı büyük ölçüde mümkün olduğu gorülmüştür.
  • Conference Object
    Ölçülmüş Çydf Verilerinin Lafortune Modeli ile Etkin Gösterimi
    (IEEE, 2010) Ozan, Şükrü; Gümüştekin, Şevket
    The bi-directional reflectance distribution function (BRDF) describes the appearance of a material by its interaction with light. In this study, Lafortune BRDF model is fitted to densely sampled measured BRDF data by using Levenberg - Marquardt Algorithm. The obtained results are visualised by a physically based ray tracing software and the proposed method is analysed. ©2010 IEEE.
  • Article
    Citation - Scopus: 1
    Reconstruction of Geometrical and Reflection Properties of Surfaces by Using Structured Light Imaging Technique
    (Türkiye Klinikleri Journal of Medical Sciences, 2018) Ozan, Şükrü; Gümüştekin, Şevket
    When a robust and dense surface reconstruction is aimed, structured light imaging techniques are usually much appreciated. In this paper we propose a method to reconstruct both geometrical and reflective properties of surfaces by using structured light imaging. We use a technique where a camera and a projector are both treated as viewing devices. They are calibrated in the same manner. Each visible point can be correctly located on both image planes without solving a correspondence problem; hence, a dense reconstruction can be obtained. Since both the camera and the projector are explicitly calibrated, lighting and viewing directions can be identified for each surface point. It is also possible to measure reflected radiance by using high dynamic range (HDR) images for each surface point. The lighting and viewing directions that are known after calibration are combined with the reflected radiance and the incoming irradiance measurements to determine the bidirectional reflectance distribution function (BRDF) values of the material at the reconstructed surface points. We illustrate the reconstruction of surface reflection properties of sample surfaces by fitting the Phong BRDF model to the BRDF measurements.