Browsing by Subject "Three-dimensional imaging."

Now showing 1 - 8 of 8

Open Access
Camera-based 3D interaction for handheld devices
(2010) Pekin, Tacettin Sercan
Using handheld devices is a very important part of our daily life. Interacting with them is the most unavoidable part of using them. Today’s user interface designs are mostly adapted from desktop computers. The result of this was difficulties of using handheld devices. However processing power, new sensing technologies and cameras are already available for mobile devices. This gives us the possibility to develop systems to communicate through different modalities. This thesis proposes some novel approaches, including finger detection, finger tracking and object motion analysis, to allow efficient interaction with mobile devices. As the result of my thesis, a new interface between users and mobile devices is created. This is a new way of interaction with the mobile device. It enables direct manipulation on objects. The technique does not require any extra hardware. The interaction method, maps an object’s motion (such as a finger’s or a predefined marker’s motion) to a virtual space to achieve manipulation which is moving in front of the camera. For Finger Detection, a new method is created based on the usage of the mobile devices and structure of thumb. A fast two dimensional color-based scene analysis method is applied to solve the problem. For Finger Tracking, a new method is created based on the movement ergonomics of thumb when holding the mobile device on hand. Extracting the three dimensional movement from the two dimensional RGB data is an important part of this section of the study. A new 3D pointer data and pointer image is created for usage with 3D input and 3D interaction of 3D scenes. Also direct manipulation for low cost is achieved.
Open Access
Comparing designers' cognitive behaviors in geometry-based and parametric 3D modeling environments
(2014) Tünger, Çetin
Digital design area has been constantly developed by scientific studies, but it is observed that studies in this area have mostly focused on the technical aspects of the subject (i.e. development of new tools and courses). User, tool, and process are three fundamental elements of a digital design system, so there is a need for studies on users and processes as well as tools. This study was carried out to understand and compare the cognitive behaviors of designers in conventional geometry-based and parametric 3D modeling environments within the framework mentioned above. While the geometry-based modeling tools are based on creation and the modification of the geometry, parametric modeling environments include an algorithmic structure underlying the form generation process. The study utilized Rhino as a geometric tool and Grasshopper as a parametric 3D tool. Six design students participated in the study. The data was collected by protocol analysis method and analyzed with a content-oriented coding scheme developed in this study. Results indicated that the cognitive actions of designers were significantly different in geometric and parametric modeling environments.
Open Access
A context aware approach for enhancing gesture recognition accuracy on handheld devices
(2010) Yıldırım, Hacı Mehmet
Input capabilities (e.g. joystick, keypad) of handheld devices allow users to interact with the user interface to access the information and mobile services. However, these input capabilities are very limited because of the mobile convenience. New input devices and interaction techniques are needed for handheld devices. Gestural interaction with accelerometer sensor is one of the newest interaction techniques on mobile computing. In this thesis, we introduce solutions that can be used for automatically enhancing the gesture recognition accuracy of accelerometer sensor, and as a standardized gesture library for gestural interaction on touch screen and accelerometer sensor. In this novel solution, we propose a framework that decides on suitable signal processing techniques for acceleration sensor data for a given context of the user. First system recognizes the context of the user using pattern recognition algorithm. Then, system automatically chooses signal ltering techniques for recognized context, and recognizes gestures. Gestures are also standardized for better usage. In this work, we also present several experiments which show the feasibility and e ectiveness of our automated gesture recognition enhancement system.
Open Access
Cubist style rendering of 3D virtual environments
(2012) Arpa, Sami
Cubism, pioneered by Pablo Picasso and Georges Braque, was a breakthrough in art, influencing artists to abandon existing traditions. In this thesis, we present a novel approach for cubist rendering of 3D synthetic environments. Rather than merely imitating cubist paintings, we apply the main principles of Analytical Cubism to 3D graphics rendering. In this respect, we develop a new cubist camera providing an extended view, and a perceptually based spatial imprecision technique that keeps the important regions of the scene within a certain area of the output. Additionally, several methods to provide a painterly style are applied. We demonstrate the effectiveness of our extending view method by comparing the visible face counts in the images rendered by the cubist camera model and the traditional perspective camera. Besides, we give an overall discussion of final results and apply user tests in which users compare our results very well with Analytical Cubist paintings but not Synthetic Cubist paintings.
Open Access
A dept perception aware pen-based 3D sketching system
(2012) Yıldız, Cansın
This thesis proposes a method that resembles a natural pen and paper interface to create curve based 3D sketches. The system is particularly useful for representing initial 3D design ideas without much effort. Users interact with the system by the help of a pressure sensitive pen tablet, and a camera. The input strokes of the users are projected onto a drawing plane, which serves as a paper that they can place anywhere in the 3D scene. The resulting 3D sketch is visualized emphasizing depth perception by implementing several monocular depth cues, including motion parallax performed by tracking user’s head position. Our evaluation involving several naive users suggest that the system is suitable for a broad range of users to easily express their ideas in 3D. We further analyze the system with the help of an architect to demonstrate the expressive capabilities of the system that a professional can benefit.
Open Access
Generating 3D thumbnails for 3D contents
(2010) Yiğit, Yeliz
Creating effective thumbnails is a challenging task because finding important features and preserving the quality of the content is difficult. Additionally, as the popularity of 3D technologies is increasing, the usage area of 3D contents and the 3D content databases are expanding. However, for these contents, 2D thumbnails are insufficient since the current methods for generating them do not maintain the important and recognizable features of the content and give the idea of the content. In this thesis, we introduce a new thumbnail format, 3D thumbnail that helps users to understand the content of the 3D graphical scene or 3D video + depth by preserving the recognizable features and qualities. For creating 3D thumbnails, we developed a framework that generates 3D thumbnails for different 3D contents in order to create meaningful and qualified thumbnails. Thus, the system selects the best viewpoint in order to capture the scene with a high amount of detail for 3D graphical scenes. On the other hand, this process is different for 3D videos. In this case, by a saliency-depth based approach, we find the important objects on the selected frame of the 3D video and preserve them. Finally, after some steps such as placement, 3D rendering etc., the resulting thumbnails give more glorified information about the content. Finally, several experiments are presented which show that our proposed 3D thumbnail format is statistically (p <0.05 ) better than 2D thumbnails.
Open Access
Hyper-reality of a three-dimensional cinematic experience within postmodern era
(2012) Sungur, Günışık
This research aims to analyze hyper-reality of three-dimensional cinematic experience within postmodern era. In the study, (illusion of) realistic aspect of a cinematic experience is taken into account in order to examine the „shifts‟ occurred in the expectations and the understanding of a cinematic experience due to changes within the social paradigm. In this mentioned context, the movie Avatar (2009) is analyzed through its hyper-realistic characteristics with respect to postmodernist notion of understanding. As a result, it could be said that, due to changes on the mode of thought, any understanding could be shaped inevitably, under the effect of the „norms‟ that came with the mode of thought. In this study, the point tried to be shown is that the changes in the mode of thought has a reflection on the understanding of a cinematic experience.
Open Access
Three-dimensional integral imaging based capture and display system using digital programmable Fresnel lenslet arrays
(2012) Yöntem, Ali Özgür
A Fresnel lenslet array pattern is written on a phase-only LCoS spatial light modulator device (SLM) to replace the regular analog lenslet array in a conventional integral imaging system. We theoretically analyze the capture part of the proposed system based on Fresnel wave propagation formulation. Due to pixelation and quantization of the lenslet array pattern, higher diffraction orders and multiple focal points emerge. Because of the multiple focal planes introduced by the discrete lenslets, multiple image planes are observed. The use of discrete lenslet arrays also causes some other artefacts on the recorded elemental images. The results reduce to those available in the literature when the effects introduced by the discrete nature of the lenslets are omitted. We performed simulations of the capture part. It is possible to obtain the elemental images with an acceptable visual quality. We also constructed an optical integral imaging system with both capture and display parts using the proposed discrete Fresnel lenslet array written on a SLM. Optical results, when self-luminous objects, such as an LED array, are used indicate that the proposed system yields satisfactory results. The resulting system consisting of digital lenslet arrays offers a flexible integral imaging system. Thus, to increase the visual performance of the system, previously available analog solutions can now be implemented digitally by using electro-optical devices. We also propose a method and present applications of this method that converts a diffraction pattern into an elemental image set in order to display them on a display-only integral imaging setup. We generate elemental images based on diffraction calculations as an alternative to commonly used ray tracing methods. Ray tracing methods do not accommodate the interference and diffraction phenomena. Our proposed method enables us to obtain elemental images from a holographic recording of a 3D object/scene. The diffraction pattern can be either numerically generated or digitally acquired from optical input. The method shows the connection between a hologram (diffraction pattern) of a 3D object and an elemental image set of the same 3D object. We obtained optical reconstructions with a display-only integral imaging setup where we used a digital lenslet array. We also obtained numerical reconstructions, again by using the diffraction calculations, for comparison. The digital and optical reconstruction results are in good agreement. Finally, we showed a method to obtain an orthoscopic image of a 3D object. We converted an elemental image set that gives real pseudoscopic reconstruction into another elemental image set that gives real orthoscopic reconstruction. Again, we used wave propagation simulations for this purpose. We also demonstrated numerical and optical reconstructions from the obtained elemental image sets for comparison. The results are satisfactory given the physical limitations of the display system.