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Yayın Raylı sistemlerde yüksek gerilim aksamının otomatik denetimi(IEEE, 2014-04-23) Ağdoğan, Didem; Babacan, Veysel Karani; Eskil, Mustafa TanerRaylı sistemlerde yolculugun sorunsuz tamamla-nabilmesi için sistem bütünlüğü kritik öneme sahiptir. Sistem bütünlüğü, lokomotif ve vagonlar haricinde katener (yüksek gerilim) hattı, pantograf ve raylara bağlıdır. Katener hattı ve pantograf, lokomotife elektrik iletimini sağlarken rayların seviyesi pantografın elektrik hattına düzenli temasına etki eder. Raylarda oluşabilecek çöküntüler katener hattı ile pantograf arasında ark (kıvılcım) oluşumuna neden olur. Katener hattının pantograf sınırları dışına çıkması, pantografta oluşabilecek çentikler ve ark oluşumu lokomotif üzerinden anlık izlenebilir. Bu çalışmada amacımız, bu üç ögeden kaynaklanabilecek hataları kameralı bir sistemle, gerçek zamanlı ve otomatik izleyerek tren yolculuğunun güvenli ve kesintisiz yapılmasına katkıda bulunmaktır.Yayın Mathematical modeling of human facial muscles(Işık Üniversitesi, 2015-08-10) Ağdoğan, Didem; Eskil, Mustafa Taner; Işık Üniversitesi, Fen Bilimleri Enstitüsü, Bilgisayar Mühendisliği Yüksek Lisans ProgramıIn this study; a new muscle model is proposed for computation of actual muscle forces that exist during facial expressions. Modeling of facial muscle forces is done on the expression of surprise. We choose this expression as it is performed by the activation of a single(frontalis) muscle. Videos used in the study are recorded with a high resolution camera where the subject's face was painted with a rectangular grid. The first and last frames of subject's surprise expression is used for extraction of muscle forces. Feature points which are located in the first frame are manually marked on the last frame with guidance of the rectangular grid. Muscle forces that are exerted on the facial skin are computed using a massspring model and an anatomical muscle model is derived. Skin is also modelled as a nonlinear deformable tissue for more realistic results. The accuracy of the proposed model is shown through simulations.Yayın An observation based muscle model for simulation of facial expressions(Elsevier Science BV, 2018-05) Erkoç, Tuğba; Ağdoğan, Didem; Eskil, Mustafa TanerThis study presents a novel facial muscle model for coding of facial expressions. We derive this model from unintrusive observation of human subjects in the progress of the surprise expression. We use a generic and single-layered face model which embeds major muscles of the human face. This model is customized onto the human subject's face on the first frame of the video. The last frame of the video is used to project a set of manually marked feature points to estimate the 3 dimensional displacements of vertices due to facial expression. Vertex displacements are used in a mass spring model to estimate the external forces, i.e. the muscle forces on the skin. We observed that the distribution of muscle forces resemble sigmoid or hyperbolic tangent functions. We chose hyperbolic tangent function as our base model and parameterized it using least squares. We compared the proposed muscle model with frequently used models in the literature.Yayın Semi-automatic adaptation of high-polygon wireframe face models through inverse perspective projection(Springer-Verlag, 2012) Benli, Kristin Surpuhi; Ağdoğan, Didem; Özgüz, Mete; Eskil, Mustafa TanerPrecise registration of a generic 3D face model with a subject's face is a critical stage for model based analysis of facial expressions. In this study we propose a semi-automatic model fitting algorithm to fit a high-polygon wireframe model to a single image of a face. We manually mark important landmark points both on the wireframe model and the face image. We carry out an initial alignment by translating and scaling the wireframe model. We then translate the landmark vertices in the 3D wireframe model so that they coincide with inverse perspective projections of image landmark points. The vertices that are not manually labeled as landmark are translated with a weighted sum of vectorial displacement of k neighboring landmark vertices, inversely weighted by their 3D distances to the vertex under consideration. Our experiments indicate that we can fit a high-polygon model to the subject's face with modest computational complexity.
