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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

COLLADA Audio : A Formal Representation of Sound in Virtual Cities by a Scene Description Language / Le son dans COLLADA : une représentation formelle du son dans les villes virtuelles avec des langages de description de scène

Chan, Shih-Han 20 December 2012 (has links)
Depuis de nombreuses années, des formats de fichier standardisés ont été conçus pour écrire, lire et échanger des descriptions de scènes 3D. Ces descriptions sont principalement faites pour des contenus visuels; les options accessibles pour les compositions audio des scènes virtuelles sont, dans les meilleurs des cas, pauvres et dans les pires, manquantes. C’est pourquoi nous proposons d’inclure une description sonore riche dans le COLLADA qui est un format standard pour d’échange d’assets numériques. La plupart des langages de description qui incluent une description sonore factorisent les éléments communs aux informations visuelles et sonores. Ces deux aspects sont par exemple décrits dans le même système de coordonnées. Cependant, dès lors qu’une description dynamique ou que des données externes sont requises, toutes les liaisons doivent être faites de manière programmée. Dans cette thèse, nous tentons de résoudre ce problème et nous proposons de donner plus de puissance créative aux sound designers même lorsque les scènes sont dynamiques ou basées sur de la synthèse procédurale. Cette solution est basée sur le schéma COLLADA dans lequel nous avons ajouté la description sonore, des capacités de scripting et des extensions externes. L’utilisation de ce langage COLLADA ainsi augmenté est illustrée à travers la création d’un paysage sonore urbain. / Standardized file formats has been conceived since many years to write, read, and exchange 3D scene descriptions. These descriptions are mainly for visual contents whereas options given for audio compositions of virtual scenes are either lacking or poor. Therefore, we propose to include a rich sound description in the COLLADA, which is a standard format for exchanging digital assets. Most scene description languages with a sound description factorize common elements needed by the graphical and auditory information. Both aspects are, for example, described with the same coordinate system. However, as soon as a dynamic description or external data are required, all the glue must be done by a programming approach. In this thesis, we address this problem and propose to give more creative power in the hands of sound designers even when the scene is dynamic or based on procedural synthesizers. This solution is based on the COLLADA schema in which we add the sound support, scripting capabilities and external extensions. The use of the augmented COLLADA language is illustrated through the creation of dynamic urban soundscape.
2

REALTIME MAPPING AND SCENE RECONSTRUCTION BASED ON MID-LEVEL GEOMETRIC FEATURES

Georgiev, Kristiyan January 2014 (has links)
Robot mapping is a major field of research in robotics. Its basic task is to combine (register) spatial data, usually gained from range devices, to a single data set. This data set is called global map and represents the environment, observed from different locations, usually without knowledge of their positions. Various approaches can be classified into groups based on the type of sensor, e.g. Lasers, Microsoft Kinect, Stereo Image Pair. A major disadvantage of current methods is the fact, that they are derived from hardly scalable 2D approaches that use a small amount of data. However, 3D sensing yields a large amount of data in each 3D scan. Autonomous mobile robots have limited computational power, which makes it harder to run 3D robot mapping algorithms in real-time. To remedy this limitation, the proposed research uses mid-level geometric features (lines and ellipses) to construct 3D geometric primitives (planar patches, cylinders, spheres and cones) from 3D point data. Such 3D primitives can serve as distinct features for faster registration, allowing real-time performance on a mobile robot. This approach works in real-time, e.g. using a Microsoft Kinect to detect planes with 30 frames per second. While previous approaches show insufficient performance, the proposed method operates in real-time. In its core, the algorithm performs a fast model fitting with a model update in constant time (O(1)) for each new data point added to the model using a three stage approach. The first step inspects 1.5D sub spaces, to find lines and ellipses. The next stage uses these lines and ellipses as input by examining their neighborhood structure to form sets of candidates for the 3D geometric primitives. Finally, candidates are fitted to the geometric primitives. The complexity for point processing is O(n); additional time of lower order is needed for working on significantly smaller amount of mid-level objects. The real-time performance suggests this approach as a pre-processing step for 3D real-time higher level tasks in robotics, like tracking or feature based mapping. In this thesis, I will show how these features are derived and used for scene registration. Optimal registration is determined by finding plane-feature correspondence based on mutual similarity and geometric constraints. Our approach determines the plane correspondence in three steps. First step computes the distance between all pairs of planes from the first scan to all pair of planes from the second scan. The distance function captures angular, distance and co-planarity differences. The resulting distances are accumulated in a distance matrix. The next step uses the distance matrix to compute the correlation matrix between planes from the first and second scan. Finally plane correspondence is found by finding the global optimal assignment from the correlation matrix. After finding the plane correspondence, an optimal pose registration is computed. In addition to that, I will provide a comparison to existing state-of-the-art algorithms. This work is part of an industry collaboration effort sponsored by the National Institute of Standards and Technology (NIST), aiming at performance evaluation and modeling of autonomous navigation in unstructured and dynamic environments. Additional field work, in the form of evaluation of real robotic systems in a robot test arena was performed. / Computer and Information Science / Accompanied by two .mp4 files.
3

Trasování významných bodů ve videosekvenci nestacionární kamery / Interest Points Tracking in Video Sequence of Non-stationary Camera

Studený, Pavel January 2016 (has links)
The thesis deals with the issue of tracking feature points earned from videosequences of hand helded camera. The work is focused on the case of moving camera and static background, and events that are associated with this case and can occur. There is studied the movement of the camera, which is given its direction and speed. The aim of this work is the election and the subsequent implementation of three fundamentally different methods suitable for tracking feature points in case of moving camera and their comparison according to set criteria. On the basis of comparison will be under pre-defined conditions chosen algorithm that is best able to deal with tracing these points.
4

Zobrazování komplexních 3D scén / Rendering Complex 3D Scenes

Mrkvička, Tomáš January 2008 (has links)
This thesis deals with representation of large and complex 3D scenes which are usually used by modern computer games. Main aim is design and implementation of data driven rendering system. Proper rendering is directed (driven) by scene description. This description is also designed with respect to scene creators whose typically do not have deep knowledge of programming languages in contrast to game programming developers. First part is focused on design of efficient scene description and its possible applications at scene rendering. Second part is focused on proper system implementation. Finally, consequently important system optimizations are mentioned too.

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