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Yayın Spectral coding of mesh geometry with a hierarchical set partitioning algorithm(Spie-Int Soc Optical Engineering, 2008) Konur, Umut; Bayazıt, Uluğ; Ateş, Hasan Fehmi; Gürgen, Sadık FikretThis work proposes a progressive mesh geometry coder, which expresses geometry information in terms of spectral coefficients obtained through a transformation and codes these coefficients using a hierarchical set partitioning algorithm that assigns right priorities to those coefficients at all bit planes. The spectral transformation used is the one proposed in [8] where the spectral coefficients are obtained by projecting the mesh geometry on an orthonormal basis determined by mesh topology. The set partitioning method used in coding, treats spectral coefficients belonging to the three spatial coordinates with the right priority at all bit planes and realizes a truly embedded system by achieving implicit bit allocation via joint coding the zeroes of coefficients at the bit planes. The experiments performed on common irregular meshes reveal that the rate-distortion performance of the coder is significantly superior to the coding system proposed in [8].Yayın Tel file geometrilerinin sıradüzensel küme bölüntüleme ile spektral kodlaması(IEEE, 2007-09-04) Konur, Umut; Bayazıt, Uluğ; Ateş, Hasan Fehmi; Gürgen, Sadık FikretÇalışmamızda bir dönüşümle elde edilen spektral katsayılar kullanılarak betimlenen tel file geometri bilgisi, katsayılara bütün bit düzlemlerinde en doğru öncelikler atanarak sıradüzensel bir küme bölüntüleme algoritmasıyla aşamalı biçimde kodlanmaktadır. Kullanılan spektral dönüşüm [8]’de önerilmekte ve geometri bilgisinin topolojiden belirlenen birimdik bir doğuray üzerine düşümlenerek katsayıların elde edilmesi ilkesine dayanmaktadır. Kodlamada kullanılan küme bölüntüleme yöntemi, üç ayrı uzamsal koordinata ait farklı katsayıların bitlerine her bit düzleminde doğru önceliği tanımakta ve katsayıların bit düzlemlerindeki sıfırları birleşik kodladığı için dolaylı bit atamasını başararak tamamen gömülü bir yapıyı sağlayabilmektedir. Yaygın düzensiz tel filelerle yapılan deneylerde önerilen yöntemin hız-bozunum başarımı, [8]’deki kodlama yönteminin hız-bozunum başarımına göre açık bir üstünlük sağlamaktadır.Yayın 3-D Mesh geometry compression with set partitioning in the spectral domain(IEEE-INST Electrical Electronics Engineers Inc, 2010-02) Bayazıt, Uluğ; Konur, Umut; Ateş, Hasan FehmiThis paper explains the development of a highly efficient progressive 3-D mesh geometry coder based on the region adaptive transform in the spectral mesh compression method. A hierarchical set partitioning technique, originally proposed for the efficient compression of wavelet transform coefficients in high-performance wavelet-based image coding methods, is proposed for the efficient compression of the coefficients of this transform. Experiments confirm that the proposed coder employing such a region adaptive transform has a high compression performance rarely achieved by other state of the art 3-D mesh geometry compression algorithms. A new, high-performance fixed spectral basis method is also proposed for reducing the computational complexity of the transform. Many-to-one mappings are employed to relate the coded irregular mesh region to a regular mesh whose basis is used. To prevent loss of compression performance due to the low-pass nature of such mappings, transitions are made from transform-based coding to spatial coding on a per region basis at high coding rates. Experimental results show the performance advantage of the newly proposed fixed spectral basis method over the original fixed spectral basis method in the literature that employs one-to-one mappings.Yayın A cost-efficient bit-serial architecture for sub-pixel motion estimation of H.264/AVC(IEEE Computer Soc, 2008) Fatemi, Mohammad Reza Hosseiny; Ateş, Hasan Fehmi; Salleh, Rosli BinThis paper presents a new VLSI architecture for sub-pixel motion estimation in H.264/AVC encoder. It is based on an interpolation free algorithm that causes a high level reduction on memory requirement, hardware resources and computational complexity. A high performance, bit-serial pipeline architecture is proposed for quarter pixel accurate motion estimation which supports real-time H.264 encoding. Due to the bit-serial, modular and reusable architecture, it provides significant improvement in area cost (at least 390) and increases the macroblock processing speed almost 6 times when compared with the previous designs. The proposed architecture is suitable for portable multimedia devices where the memory and power consumption are limited.
