Browsing by Subject "Computer animation."
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Item Open Access 3D hair design and key frame animation in real time(2008) Başarankut, BarkınComputer generated animations of humans, animals and all other kinds of objects have been studied extensively during the last two decades. The key for creating good animations has been to correctly imitate the behaviors of real objects and reflect these into computer generated images. With the rapid development of computer technology, creating realistic simulations has become possible, and the most striking components of these realistic animations happen to be the most dynamic (moving) parts; hair, in the case of human animations. With the development of high quality hair animations, the concern is not only creating physically correct animations, but also controlling these animations. An implementation of a key frame hair animation creation system, supported by a hair design tool, helping to model and animate hair easily, and provide these functionalities in real time is the aim of the proposed system. This work reviews several hair animation and sketching techniques, and proposes a system that provides a complete level of control (capable of controlling even the individual hair strands) of key frame animation and hair design in real time.Item Open Access 3D hair sketching for real-time hair modeling and dynamic simulations(2008) Aras, RıfatHair has been an active research area in computer graphics society for over a decade. Different approaches have been proposed for different aspects of hair research such as modeling, simulating, animating and rendering. In this thesis, we introduce a sketch-based tool making use of direct manipulation interfaces to create hair models and furthermore simulate the created hair models under physically based constraints in real-time. Throughout the thesis, the created tool will be analyzed with respect to different aspects of the problem such as hair modeling, hair simulation, hair sketching and hair rendering.Item Open Access 3D mesh animation system targeted for multi-touch environments(2009) Ceylan, DuyguFast developments in computer technology have given rise to different application areas such as multimedia, computer games, and Virtual Reality. All these application areas are based on animation of 3D models of real world objects. For this purpose, many tools have been developed to enable computer modeling and animation. Yet, most of these tools require a certain amount of experience about geometric modeling and animation principles, which creates a handicap for inexperienced users. This thesis introduces a solution to this problem by presenting a mesh animation system targeted specially for novice users. The main approach is based on one of the fundamental model representation concepts, Laplacian framework, which is successfully used in model editing applications. The solution presented perceives a model as a combination of smaller salient parts and uses the Laplacian framework to allow these parts to be manipulated simultaneously to produce a sense of movement. The interaction techniques developed enable users to carry manipulation and global transformation actions at the same time to create more pleasing results. Furthermore, the approach utilizes the multi-touch screen technology and direct manipulation principles to increase the usability of the system. The methods described are experimented by creating simple animations with several 3D models; which demonstrates the advantages of the proposed solution.Item Open Access Animated mesh simplification based on saliency metrics(2008) Tolgay, AhmetMesh saliency identifies the visually important parts of a mesh. Mesh simplification algorithms using mesh saliency as simplification criterion preserve the salient features of a static 3D model. In this thesis, we propose a saliency measure that will be used to simplify animated 3D models. This saliency measure uses the acceleration and deceleration information about a dynamic 3D mesh in addition to the saliency information for static meshes. This provides the preservation of sharp features and visually important cues during animation. Since oscillating motions are also important in determining saliency, we propose a technique to detect oscillating motions and incorporate it into the saliency based animated model simplification algorithm. The proposed technique is experimented on animated models making oscillating motions and promising visual results are obtained.Item Open Access Animating facial images with drawings(1996) Tunali, Gamze DilekThe work presented here describes the power of 2D animation with texture mai^ping controlled by line drawings. Animation is specifically intended for facial animation and not restricted by the human face. We initially have a sequence of facial images which are taken from a video sequence of the same face and an image of another face to be animated. The aim is to animate the face image with the same expressions as those of the given video sequence. To realize the animation, a set of frames are taken from a video sequence. Key features of the first frame are I’otoscoped and the other frames are automatically rotoscoped using the first frame. Similarly, the corresponding features of the image which will be animated are rotoscoped. The key features of the first frame of the sequence and the image to be animated are mapped and using cross-synthesis procedure, other drawings for the given image are produced. Using these animated line drawings and the original image, the corresponding frame sequence is produced by image warping. The resulting sequence has the same expressions as those of the video sequence. This work encourages the reuse of animated motion by gathering facial motion sequences into a database. Furthermore, by using motion sequences of a human face, non-human characters can be animated realistically or complex characters can be animated by the help of motion sequences of simpler characters.Item Open Access Animation of human motion with inverse kinematics using nonlinear programming(2001) Abalı, A. SezginAnimation of articulated figures has always been an interesting subject of computer graphics due to a wide range of applications, like military, ergonomic design etc. An articulated figure is usually modelled as a set of segments linked with joints. Changing the joint angles brings the articulated figure to a new posture. An animator can define the joint angles for a new posture (forward kinematics). However, it is difficult to estimate the exact joint angles needed to place the articulated figure to a predefined position. Instead of this, an animator can specify the desired position for an end-effector, and then an algorithm computes the joint angles needed (inverse kinematics). In this thesis, we present the implementation of an inverse kinematics algorithm using nonlinear optimization methods. This algorithm computes a potential function value between the end-effector and the desired posture of the end-effector called goal. Then, it tries to minimize the value of the function. If the goal cannot be reached due to constraints then an optimum solution is found and applied by the algorithm. The user may assign priority to the joint angles by scaling initial values estimated by the algorithm. In this way, the joint angles change according to the animator’s priorityItem Open Access Data-driven synthesis of realistic human motion using motion graphs(2014) Dirican, HüseyinRealistic human motions is an essential part of diverse range of media, such as feature films, video games and virtual environments. Motion capture provides realistic human motion data using sensor technology. However, motion capture data is not flexible. This drawback limits the utility of motion capture in practice. In this thesis, we propose a two-stage approach that makes the motion captured data reusable to synthesize new motions in real-time via motion graphs. Starting from a dataset of various motions, we construct a motion graph of similar motion segments and calculate the parameters, such as blending parameters, needed in the second stage. In the second stage, we synthesize a new human motion in realtime, depending on the blending techniques selected. Three different blending techniques, namely linear blending, cubic blending and anticipation-based blending, are provided to the user. In addition, motion clip preference approach, which is applied to the motion search algorithm, enable users to control the motion clip types in the result motion.Item Open Access Example based retargeting human motion to arbitrary mesh models(2013) Yaz, İlker O.Animation of mesh models can be accomplished in many ways, including character animation with skinned skeletons, deformable models, or physic-based simulation. Generating animations with all of these techniques is time consuming and laborious for novice users; however adapting already available wide-range human motion capture data might simplify the process signi cantly. This thesis presents a method for retargeting human motion to arbitrary 3D mesh models with as little user interaction as possible. Traditional motion retargeting systems try to preserve original motion as is, while satisfying several motion constraints. In our approach, we use a few pose-to-pose examples provided by the user to extract desired semantics behind retargeting process by not limiting the transfer to be only literal. Hence, mesh models, which have di erent structures and/or motion semantics from humanoid skeleton, become possible targets. Also considering mesh models which are widely available and without any additional structure (e.g. skeleton), our method does not require such a structure by providing a build-in surface-based deformation system. Since deformation for animation purpose can require more than rigid behaviour, we augment existing rigid deformation approaches to provide volume preserving and cartoon-like deformation. For demonstrating results of our approach, we retarget several motion capture data to three well-known models, and also investigate how automatic retargeting methods developed considering humanoid models work on our models.Item Open Access Human motion control using inverse kinematics(2003) Memişoğlu, AydemirArticulated figure animation receives particular attention of the computer graphics society. The techniques for animation of articulated figures range from simple interpolation between keyframes methods to motion-capture techniques. One of these techniques, inverse kinematics, which is adopted from robotics, provides the animator the ability to specify a large quantity of motion parameters that results with realistic animations. This study presents an interactive hierarchical motion control system used for the animation of human figure locomotion. We aimed to develop an articulated figure animation system that creates movements , like goal-directed motion and walking by using motion control techniques at different levels. Inverse Kinematics using Analytical Methods (IKAN) software, which was developed at the University of Pennsylvania, is utilized for controlling the motion of the articulated body using inverse kinematics.Item Open Access MARS: a tool-based modeling, animation and parallel rendering system(1992) Aktıhanoğlu, MuratA b stract: This thesis describes a system for modeling, animating, previewing and rendering articulated objects. Tl^^ system has a modeler which models objects, consisting of joints and segments. The animatoi- interactively positions the articulated object in its stick, control vertex or rectangular prism representation into the keyframes, interpolates inbetweens and previews the motion in real time. Then the data representing the motion and the models is sent to a multicomputer {iPSC/2 Ilypercube^). The frames are rendered in parallel by distributed processing techniques, exploiting the coherence between successive frames, thus cutting down the rendering time significantly. The main aim of this research has been to make a detailed study on rendering of a sequence of 3D scenes. The results show that due to an inherent correlation between the 3D scenes, a much more efficient rendering than the conventional sequential one can be done.Item Open Access Modeling 3D objects with free-form surfaces using 2D sketches(2011) Akatürk, EmreUsing sketches for 3D modelling is a popular research area, which is expected since using 2D sketches feels natural to most of the artists. Many techniques have been proposed to enable an intuitive and competent tool for 3D object creation. In the light of the previous research in this area, we designed a system that enables creation of 3D free-form objects with details. Our system aims to enable users to easily create simple free-form objects using strokes and perturb their surfaces using sketches that provide contours of details and shading information. We provide the user with the ability to create a 3D simple object just by drawing its silhouette. We take this stroke input and create a simple 3D object. Then we allow the user to shade the parts of the 2D silhouette drawn before. We take the shading information and use shape from shading techniques to create a height map and apply the height map on the surface of the object to construct a perturbed surface for the previously created mesh. With our system, it is possible to create and modify 3D meshes easily and intuitively.Item Open Access Modeling and animating personalized faces(2002) Erol, FatihA very important and challenging problem in computer graphics is modeling and animation of individualized face models. In this thesis, we describe a facial modeling and animation system attempting to address this problem. The system uses muscle-based generic face model and deforms it using deformation techniques to model individualized faces. Two orthogonal photos of the real faces are used for this purpose. Image processing techniques are employed to extract certain features on the photographs, which are then refined manually by the user through the facilities of the user interface of the system. The feature points located on the frontal and side views of a real face are used to deform the generic model. Then, the muscle vectors in the individualized face model are arranged accordingly. Individualized face models produced in this manner are animated using parametric interpolation techniques.Item Open Access Modeling and animation of brittle fracture in three dimensions(2007) Küçükyılmaz, AyşeThis thesis describes a system for simulating fracture in brittle objects. The system combines rigid body simulation methods with a constraint-based model to animate fracturing of arbitrary polyhedral shaped objects under impact. The objects are represented as sets of masses, where pairs of adjacent masses are connected by a distance-preserving linear constraint. The movement of the objects is normally realized by unconstrained rigid body dynamics. The fracture calculations are only done at discrete collision events. In case of an impact, the forces acting on the constraints are calculated. These forces determine how and where the object will break. The problem with most of the existing fracture systems is that they only allow simulations to be done offline, either because the utilized techniques are computationally expensive or they require many small steps for accuracy. This work presents a near-real-time solution to the problem of brittle fracture and a graphical user interface to create realistic animations.Item Open Access A multi scale motion saliency method for keyframe extraction from motion capture sequences(2010) Halit, CihanMotion capture is an increasingly popular animation technique; however data acquired by motion capture can become substantial. This makes it di cult to use motion capture data in a number of applications, such as motion editing, motion understanding, automatic motion summarization, motion thumbnail generation, or motion database search and retrieval. To overcome this limitation, we propose an automatic approach to extract keyframes from a motion capture sequence. We treat the input sequence as motion curves, and obtain the most salient parts of these curves using a new proposed metric, called 'motion saliency'. We select the curves to be analyzed by a dimension reduction technique, Principal Component Analysis. We then apply frame reduction techniques to extract the most important frames as keyframes of the motion. With this approach, around 8% of the frames are selected to be keyframes for motion capture sequences. We have quanti ed our results both mathematically and through user tests.Item Open Access Perceived quality assessment in object-space for animated 3D models(2012) Yakut, Işıl DoğaComputational models and methods to handle 3D graphics objects continue to emerge with the wide-range use of 3D models and rapid development of computer graphics technology. Many 3D model modification methods exist to improve computation and transfer time of 3D models in real-time computer graphics applications. Providing user with the least visually-deformed model is essential for 3D modification tasks. In this thesis, we propose a method to estimate the visually perceived differences on animated 3D models. The model makes use of Human Visual System models to mimic visual perception. It can also be used to generate a 3D sensitivity map for a model to act as a guide during the application of modifications. Our approach gives a perceived quality measure using 3D geometric representation by incorporating two factors of Human Visual System (HVS) that contribute to perception of differences. First, spatial processing of human vision model enables us to predict deformations on the surface. Secondly, temporal effects of animation velocity are predicted. Psychophysical experiment data is used for both of these HVS models. We used subjective experiments to verify the validity of our proposed method.Item Open Access Real time physics-based augmented fitting room using time-of-flight cameras(2013) Gültepe, UmutThis thesis proposes a framework for a real-time physically-based augmented cloth tting environment. The required 3D meshes for the human avatar and apparels are modeled with speci c constraints. The models are then animated in real-time using input from a user tracked by a depth sensor. A set of motion lters are introduced in order to improve the quality of the simulation. The physical e ects such as inertia, external and forces and collision are imposed on the apparel meshes. The avatar and the apparels can be customized according to the user. The system runs in real-time on a high-end consumer PC with realistic rendering results.Item Open Access Real-time fur modeling with simulation of physical effects(2012) Arıyürek, SinanFur is one of the important visual aspects of animals and it is quite challenging to model it in computer graphics. This is due to rendering and animating high amounts of geometry taking excessive time in our personal computers. Thus in computer games most of the animals are without fur or covered with a single layer of texture. But these current methods do not provide the reality and even if the rendering in the game is realistic the fur is omitted. There have been several models to render a fur, but the methods that incorporate rendering are not in real-time, on the other hand most of the real-time methods omit many of the natural aspects , such as; texture lighting, shadow and animation. Thus the outcome is not sufficient for realistic gaming experience. In this thesis we propose a real-time fur represantation that can be used on 3D objects. Moreover, we demonstrate how to; render, animate and burn this real-time fur.Item Open Access Real-time parameterized locomotion generation(2008) Akbay, MuzafferReuse and blending of captured motions for creating realistic motions of human body is considered as one of the challenging problems in animation and computer graphics. Locomotion (walking, running and jogging) is one of the most common types of daily human motion. Based on blending of multiple motions, we propose a two-stage approach for generating locomotion according to userspecified parameters, such as linear and angular velocities. Starting from a large dataset of various motions, we construct a motion graph of similar short motion segments. This process includes the selection of motions according to a set of predefined criteria, the correction of errors on foot positioning, pre-adjustments, motion synchronization, and transition partitioning. In the second stage, we generate an animation according to the specified parameters by following a path on the graph during run-time, which can be performed in real-time. Two different blending techniques are used at this step depending on the number of the input motions: blending based on scattered data interpolation and blending based on linear interpolation. Our approach provides an expandable and efficient motion generation system, which can be used for real time applications.Item Open Access Real-time simulation and visualization of deformations on heightfields(2010) Yalçın, M. AdilThe applications of computer graphics raise new expectations, such as realistic rendering, real-time dynamic scenes and physically correct simulations. The aim of this thesis is to investigate these problems on the height eld structure, an extended 2D model that can be processed e ciently by data-parallel architectures. This thesis presents methods for simulation of deformations on height eld as caused by triangular objects, physical simulation of objects interacting with height eld and advanced visualization of deformations. The height eld is stored in two di erent resolutions to support fast rendering and precise physical simulations as required. The methods are implemented as part of a large-scale height- eld management system, which applies additional level of detail and culling optimizations for the proposed methods and data structures. The solutions provide real-time interaction and recent graphics hardware (GPU) capabilities are utilized to achieve real-time results. All the methods described in this thesis are demonstrated by a sample application and performance characteristics and results are presented to support the conclusions.Item Open Access Realistic rendering of a multi-layered human body model(2003) Yeşil, Mehmet ŞahinIn this thesis study, a framework is proposed and implemented for the realistic rendering of a multi-layered human body model while it is moving. The proposed human body model is composed of three layers: a skeleton layer, a muscle layer, and a skin layer. The skeleton layer, represented by a set of joints and bones, controls the animation of the human body model using inverse kinematics. Muscles are represented by action lines, which are defined by a set of control points. The action line expresses the force produced by a muscle on the bones and on the skin mesh. The skin layer is modeled in a 3D modeler and deformed during animation by binding the skin layer to both the skeleton layer and the muscle layer. The skin is deformed by a two-step algorithm according to the current state of the skeleton and muscle layers. In the first step, the skin is deformed by a variant of the skinning algorithm, which deforms the skin based on the motion of the skeleton. In the second step, the skin is deformed by the underlying muscular layer. Visual results produced by the implementation is also presented. Performance experiments show that it is possible to obtain real-time frame rates for a moderately complex human model containing approximately 33,000 triangles on the skin layer