Browsing by Subject "Digital television"

Now showing 1 - 17 of 17

Open Access
3D forest fire propagation simulation
(IEEE, 2008-05) Köse, Kıvanç; Grammalidis, N.; Yılmaz, E.; Çetin, A. Enis
The increase in the number of forest fires in the last few years dispatch governments to take precautions. Besides prevention, early intervention is also very important in fire fighting. If the firefighters know where the fire will be in some time, it would be easier for them to stop the fire. Therefore a big need for simulating the fire behavior exists. In this paper we are proposing a system which can simulate the propagation of fire in time. Also this system can visualize the propagation of fire in any 3D-GIS environment, that accepts KMZ as a file format. Besides, any user demanded data can be visualized on the map of the system. This gives the chance of fire planning to firefighters. The system can visualize its results on 3D screens in 3D. Therefore, a better understanding of the terrain can be obtained. ©2008 IEEE.
Open Access
Animation of boiling phenomena
(IEEE, 2008-05) Bülbül, Abdullah; Küçüktunç, Onur; Özgüç, Bülent
Phenomenon of boiling is a challenging topic for computer graphics due to its complex hydrodynamics and formulation. Realistic fluid animations require very heavy three-dimensional fluid flow calculations, and surface estimations as well. However, realism and performance are the two important objectives of the boiling animation for a real-time application. We present an efficient method for the simulation of boiling water in this paper. The method is based on modeling the bubbles and waves as particles. Grid-based approach is used both for the heating and the fluid surface. Our technique makes it possible to produce the animation of boiling phenomena nearly in real-time. ©2008 IEEE.
Open Access
Bessel functions-based reconstruction of non-uniformly sampled diffraction fields
(IEEE, 2007) Uzunov, V.; Esmer, G. Bora; Gotchev, A.; Onural, Levent; Özaktaş, Haldun M.
A discrete computational model for the diffraction process is essential in forward problems related to holographic TV. The model must be as general as possible, since the shape of the displayed objects does not bear any restrictions. We derive a discrete diffraction model which suits the problem of reconstruction of diffraction fields from a set of non-uniformly distributed samples. The only restriction of the model is the wave nature of the field. The derivation takes advantage of changing the spatial and frequency coordinates to polar form and ends up with a model stated in terms of Bessel functions. The model proves to be a separable orthogonal basis. It shows rapid convergence when evaluated in the framework of the non-uniform sampling problem.
Open Access
Circularly configured multi-SLM holographic display system
(IEEE, 2011) Yaraş, Fahri; Kang, Hoonjong; Onural, Levent
The designed circular holographic display system produces ghost-like 3D optical reconstructions of a computer generated 3D model. System uses six phase-only reflective-type spatial light modulators (SLMs) that are configured circularly. Alignment of the SLMs are successful and gap problem is solved by using half-mirrors. The total number of pixels of the resultant display is 11520 1080. Reconstructions show that increase in the viewing angle is significant compared to the single SLM case. With the help of the proposed system, observer can see the reconstructions binocularly. As a result, comfortable 3D perception is achieved. In order to avoid eye-hazard, LED illumination is also used as an alternative light source. Experimental results are satisfactory. Proposed system can be used as a holographic display system.
Open Access
Connectivity-guided adaptive lifting transform for image like compression of meshes
(IEEE, 2007-05) Köse, Kıvanç; Çetin, A. Enis; Güdükbay, Uğur; Onural, Levent
We propose a new connectivity-guided adaptive wavelet transform based mesh compression framework. The 3D mesh is first transformed to 2D images on a regular grid structure by performing orthogonal projections onto the image plane. Then, this image-like representation is wavelet transformed using a lifting structure employing an adaptive predictor that takes advantage of the connectivity information of mesh vertices. Then the wavelet domain data is encoded using "Set Partitioning In Hierarchical Trees" (SPIHT) method or JPEG2000. The SPIHT approach is progressive because the resolution of the reconstructed mesh can be changed by varying the length of the 1D data stream created by the algorithm. In JPEG2000 based approach, quantization of the coefficients determines the quality of the reconstruction. The results of the SPIHT based algorithm is observed to be superior to JPEG200 based mesh coder and MPEG-3DGC in rate-distortion.
Open Access
Design and implementation of a DMD based volumetric 3D display
(IEEE, 2008-05) Yücesoy, Veysel; Tunaoǧlu, Doruk; Kovachev, Metodi; Ilieva, Rossitza; Onural, Levent
A real image swept-volume volumetric display is developed. A piston type moving screen is used to obtain the desired volume. A commercially available DMD device is used to project 2D slices of a 3D frame. There is a varying magnification effect during the projection because of the optical design of the system; raw 3D video frames are processed by a software to generate the appropriate 2D slices by also correcting the magnification. Synchronization between the hardware and the software is achieved via a microcontroller. The overall system is capable of printing 12 3D frames per second where a 3D frame consists of 90 2D slices with a resolution varying from 512x512 to 450x450 (approx. 20M voxels per one 3D frame). Although some flickering effect is observed due to rather low 3D frame rate, results are visually satisfactory. ©2008 IEEE.
Open Access
Error resilient layered stereoscopic video streaming
(IEEE, 2007) Tan, Ahmet Serdar; Aksay, A.; Bilen, Ç.; Bozdağı-Akar, G.; Arıkan, Erdal
In this paper, error resilient stereoscopic video streaming problem is addressed. Two different Forward Error Correction (FEC) codes namely Systematic LT and RS codes are utilized to protect the stereoscopic video data against transmission errors. Initially, the stereoscopic video is categorized in 3 layers with different priorities. Then, a packetization scheme is used to increase the efficiency of error protection. A comparative analysis of RS and LT codes are provided via simulations to observe the optimum packetization and UEP strategies.
Open Access
Keyframe reduction techniques for motion capture data
(IEEE, 2008-05) Önder, Onur; Güdükbay, Uğur; Özgüç, Bülent; Erdem, T.; Erdem, Ç.; Özkan, M.
Two methods for keyframe reduction of motion capture data are presented. Keyframe reduction of motion capture data enables animators to easily edit motion data with smaller number of keyframes. One of the approaches achieves keyframe reduction and noise removal simultaneously by fitting a curve to the motion information using dynamic programming. The other approach uses curve simplification algorithms on the motion capture data until a predefined threshold of number of keyframes is reached. Although the error rate varies with different motions, the results show that curve fitting with dynamic programming performs as good as curve simplification methods. ©2008 IEEE.
Open Access
Motion control for realistic walking behavior using inverse kinematics
(IEEE, 2007-05) Memişoǧlu, Aydemir; Güdükbay,Uğur; Özgüç, Bülent
This study presents an interactive hierarchical motion control system for the animation of human figure locomotion. The articulated figure animation system creates movements using motion control techniques at different levels, like goal-directed motion and walking. Inverse Kinematics using Analytical Methods (IKAN) software, developed at the University of Pennsylvania, is utilized for controlling the motion of the articulated body. © 2007 IEEE.
Open Access
Multi-SLM holographic display system with planar configuration
(IEEE, 2010) Yaraş, Fahri; Kang, Hoonjong; Onural, Levent
Holographic display system that uses six phase-only spatial light modulators (SLMs) performs holographic reconstructions from the phase-hologram of a point cloud that is extracted from 3D object. The SLMs are tiled as a three by two matrix on a virtual planar surface. The alignment is successful and the display system generates large holographic reconstructions. The proposed system can be used either to obtain reconstructions of large objects with a narrow field of view or reconstructions of smaller objects with a broader field of view. Therefore, since field of view is broader for smaller objects, observer has the flexibility to move around the reconstruction within a larger angle. This flexibility increases the motion parallax and as a consequence it increases the quality of 3D perception. Results show that even with three SLMs in horizontal direction the 3D perception is significantly increased. Experimental results are satisfactory.
Open Access
Performance assessment of a diffraction field computation method based on source model
(IEEE, 2008-05) Esmer, G. Bora; Onural, Levent; Özaktaş, Haldun M.; Uzunov, V.; Gotchev, A.
Efficient computation of scalar optical diffraction field due to an object is an essential issue in holographic 3D television systems. The first step in the computation process is to construct an object. As a solution for this step, we assume that an object can be represented by a set of distributed data points over a space. The second step is to determine which algorithm provides better performance. The source model whose performance is investigated is based on superposition of the diffraction fields emanated from the hypothetical light sources located at the given sample points. Its performance is evaluated according to visual quality of the reconstructed field and its algorithmic complexity. Source model provides acceptable reconstructed patterns when the region in which the samples are given has a narrow depth along the longitudinal direction and a wide extent along the transversal directions. Also, the source model gives good results when the cumulative field at the location of each point due to all other sources tends to be independent of that location. ©2008 IEEE.
Open Access
Piecewise-planar 3D reconstruction in rate-distortion sense
(IEEE, 2007-05) İmre, E.; Güdükbay, Uğur; Alatan, A. A.
In this paper, a novel rate-distortion optimization inspired 3D piecewise-planar reconstruction algorithm is proposed. The algorithm refines a coarse 3D triangular mesh, by inserting vertices in a way to minimize the intensity difference between an image and its prediction. The preliminary experiments on synthetic and real data indicate the validity of the proposed approach.
Open Access
Practical and realistic animation of cloth
(IEEE, 2007-05) Bayraktar, Serkan; Güdükbay, Uğur; Özgüç, Bülent
In this paper, we propose a system for the practical animation of cloth materials. A mass spring based cloth model is used. Explicit time integration methods are used to solve the equations of motion. We update the spring constants dynamically according to the net force acting on them. In this way, spring constants do not grow arbitrarily to introduce numerical instability and realistic cloth appearance without over elongation is obtained. © 2007 IEEE.
Open Access
Reconstruction of scalar diffraction field from distributed data points over 3D space
(IEEE, 2007) Esmer, G. Bora; Uzunov, V.; Onural, Levent; Gotchev, A.; Özaktaş, Haldun M.
Diffraction field computation is an important task in the signal conversion stage of the holographic 3DTV. We consider an abstract setting, where the diffraction field of the desired 3D scene to be displayed is given by discrete samples distributed over 3D space. Based on these samples, a model of the diffraction field should be built to allow the field computation at any desired point. In our previous works, we have proved our concepts for the simplistic 2D case. In this paper, we generalize the earlier proposed techniques, namely the projection onto convex sets and conjugate gradient based techniques and test them for their computational efficiency and memory requirements for a specific 3D case.
Open Access
Research trends in holographic 3DTV displays
(IEEE, 2009) Onural, Levent
Holographic 3DTV and especially displays are attracting more attention. There are SLM based laboratory prototypes. Current images can be viewed from a very narrow angle. Satisfactory holographic displays can be expected within a decade.
Open Access
Robust transmission of multi-view video streams using flexible macroblock ordering and systematic LT codes
(IEEE, 2007) Argyropoulos, S.; Tan, A. Serdar; Thomos, N.; Arıkan, Erdal; Strintzis, M. G.
The transmission of fully compatible H.264/AVC multi-view video coded streams over packet erasure networks is examined. Macroblock classification into unequally important slice groups is considered using the Flexible Macroblock Ordering (FMO) tool of H.264/AVC Systematic LT codes are used for error protection due to their low complexity and advanced performance. The optimal slice grouping and channel rate allocation are jointly determined by an iterative optimization algorithm based on dynamic programming. The experimental evaluation clearly demonstrates the validity of the proposed method.
Open Access
Simulation of water drops on a surface
(IEEE, 2008-05) Algan, Eren; Kabak, Mustafa; Özgüç, Bülent; Çapin, Tolga
We have designed and implemented a model for rendering and animating water drops moving on a surface under physical effects such as gravity, surface affinity and wind. For improved rendering, the output of the simulation (i.e. the animation sequence of the drops) is recorded for later offline image generation. ©2008 IEEE.