M. Abdullah Bulbul
I'm a teaching assistant of CS102. Students are always welcome when I'm in the office.
Research Interests
Recent Works
Assessing Visual Quality of 3-D Polygonal Models
Abdullah Bulbul, Tolga Capin, Guillaume Lavoué, Marius Preda IEEE Signal Processing Magazine, 28-6, p.80-90, 2011
abstract
Recent advances in evaluating and measuring the perceived visual quality of three-dimensional (3-D)
polygonal models are presented in this article, which analyzes the general process of objective
quality assessment metrics and subjective user evaluation methods and presents a taxonomy of existing solu-
tions. Simple geometric error computed directly on the 3-D models does not necessarily reflect the perceived visual quality; therefore, integrating perceptual issues for 3-D quality assessment is of great significance. This article discusses existing metrics, including perceptually based ones, computed either on 3-D data or on two-dimensional (2-D) projections, and evaluates their performance for their correlation with existing subjective studies.
A Decision Theoretic Approach to Motion Saliency in Computer Animations
Sami Arpa, Abdullah Bulbul, Tolga Capin. Motion in Games, Springer Lecture Notes in Computer Science, 2011, Volume 7060/2011, 168-179, 2011
abstract
We describe a model to calculate saliency of objects due to their motions. In a decision-theoretic fashion, perceptually significant objects inside a scene are detected. The work is based on psychological studies and findings on motion perception. By considering motion cues and attributes, we define six motion states. For each object in a scene, an individual saliency value is calculated considering its current motion state and the inhibition of return principle. Furthermore, a global saliency value is considered for each object by covering their relationships with each other and equivalence of their saliency value. The position of the object with highest attention value is predicted as a possible gaze point for each frame in the animation. We conducted several eye-tracking experiments to practically observe the motion-attention related principles in psychology literature. We also performed some final user studies to evaluate our model and its effectiveness.
A Framework for Enhancing Depth Perception in Computer Graphics
Zeynep Cipiloglu, Abdullah Bulbul, Tolga Capin. APGV, 2010
abstract & video - fuzzy rules - fuzzy logic tutorial
This paper introduces a solution for enhancing depth perception in a given 3D computer-generated scene. For this purpose, we propose a framework that decides on the suitable depth cues for a given scene and the rendering methods which provide these cues. First, the system calculates the importance of each depth cue using a fuzzy logic based algorithm which considers the target tasks in the application and the spatial layout of the scene. Then, a knapsack model is constructed to keep the balance between the rendering costs of the graphical methods that provide these cues and their contibution to depth perception. This cost-profit analysis step selects the proper rendering methods. In this work, we also present several objective and subjective experiments which show that our automated depth enhancement system is statistically (p < 0.05) better than the other method selection techniques that are tested.
Saliency for Animated Meshes with Material Properties
Abdullah Bulbul, Cetin Koca, Tolga Capin, Ugur Gudukbay. APGV, 2010
abstract & video
We propose a technique to calculate the saliency of animated meshes with material properties. The saliency computation considers multiple features of 3D meshes including their geometry, material and motion. Each feature contributes to the final saliency map which is view independent; and therefore, can be used for view dependent and view independent applications. To verify our saliency calculations, we performed an experiment in which we use an eye tracker to compare the saliencies of the regions that the viewers look with the other regions of the models. The results confirm that our saliency computation gives promising results. We also present several applications in which the saliency information is used.
A Color-Based Face Tracking Algorithm for Enhancing Interaction with Mobile Devices
Abdullah Bulbul, Zeynep Cipiloglu, Tolga Capin. The Visual Computer, 26-5, p.311-323, 2010
abstract
A color-based face tracking algorithm is proposed to be used as a human-computer interaction tool on mobile devices. The solution provides a natural means of interaction enabling a motion parallax effect in applications. The algorithm considers the characteristics of mobile use-constrained computational resources and varying environmental conditions. The solution is based on color comparisons and works on images gathered from the front camera of a device. In addition to color comparisons, the coherency of the facial pixels is considered in the algorithm. Several applications are also demonstrated in this work, which use the face position to determine the viewpoint in a virtual scene, or for browsing large images. The accuracy of the system is tested under different environmental conditions such as lighting and background, and the performance of the system is measured in different types of mobile devices. According to these measurements the system allows for accurate (7% RMS error) face tracking in real time (20-100 fps).
A Perceptual Approach for Stereoscopic Rendering Optimization
Abdullah Bulbul, Zeynep Cipiloglu, Tolga Capin. Computers & Graphics, 34-2, p.145-157, 2010
abstract
The traditional way of stereoscopic rendering requires rendering the scene for left and right eyes
separately; which doubles the rendering complexity. In this study, we propose a perceptually-based
approach for accelerating stereoscopic rendering. This optimization approach is based on the Binocular
Suppression Theory, which claims that the overall percept of a stereo pair in a region is determined by
the dominant image on the corresponding region. We investigate how binocular suppression
mechanism of human visual system can be utilized for rendering optimization. Our aim is to identify
the graphics rendering and modeling features that do not affect the overall quality of a stereo pair when
simpli?ed in one view. By combining the results of this investigation with the principles of visual
attention, we infer that this optimization approach is feasible if the high quality view has more intensity
contrast. For this reason, we performed a subjective experiment, in which various representative
graphical methods were analyzed. The experimental results veri?ed our hypothesis that a modi?cation,
applied on a single view, is not perceptible if it decreases the intensity contrast, and thus can be used for
stereoscopic rendering.
A Face Tracking Algorithm for User Interaction in Mobile Devices
Abdullah Bulbul, Zeynep Cipiloglu, Tolga Capin. Cyberworlds, 2009
abstract
A new face tracking algorithm, and a human-computer interaction technique based on this algorithm, are proposed for use on mobile devices. The face tracking algorithm considers the limitations of mobile use case - constrained computational resources and varying environmental conditions. The solution is based on color comparisons and works on images gathered from the front camera of a device. The face tracking system generates 2D face position as an output that can be used for controlling different applications. Two of such applications are also presented in this work; the first example uses face position to determine the viewpoint, and the second example enables an intuitive way of browsing large images.
Animation of Boiling Phenomena
Abdullah Bulbul, Onur Kucuktunc, Bulent Ozguc. 3DTV Conference, 2008
abstract & video
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.
Schedule