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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

Evaluating Textual Annotations with Interactive 3D Models

Gupta, Ankur 03 March 2013 (has links)
Annotations play a key role in explaining and elaborating 3D illustrations. They support users in identifying and establishing a visual link between different components within a 3D model. However, one major issue with annotating 3D illustrations is that there are no standard guidelines that clearly define which annotation type or style to use or is preferred by users in supporting learning and identifying objects at different zooming levels. Often, the decision of which style to use is influenced by size of the components being annotated and the overall look and feel (i.e., reduced occlusion and visual clutter) of the annotated view in display. In our research, we try to understand how effectively the three types of textual annotation labels (internal, external, and annotation boxes) can support users in learning, identifying, and navigating through 3D objects. We report the results of a study that evaluates the efficiency and accuracy in searching for components inside a 3D model, measures the impact on learning (in recalling the names of various components and their locations), and analyzes for user preferences in interacting with a 3D model on a mobile form factor at different zooming levels. Results of our study reflect that participants preferred external style annotations over internal and box style annotations, and that the participant’s performance (for both efficiency and accuracy) in searching for components inside a 3D model was highest with external style annotations. We also found that participants recalled more components when annotated with external styles annotations. Our findings suggest that of the three textual annotation styles considered in this study, external style annotation is the best annotation style to use in an annotated 3D model. / Annotations play a key role in explaining and elaborating 3D illustrations. They support users in identifying and establishing a visual link between different components within a 3D model. However, one major issue with annotating 3D illustrations is that there are no standard guidelines that clearly define which annotation type or style to use or is preferred by users in supporting learning and identifying objects at different zooming levels. Often, the decision of which style to use is influenced by size of the components being annotated and the overall look and feel (i.e., reduced occlusion and visual clutter) of the annotated view in display. In our research, we try to understand how effectively the three types of textual annotation labels (internal, external, and annotation boxes) can support users in learning, identifying, and navigating through 3D objects. We report the results of a study that evaluates the efficiency and accuracy in searching for components inside a 3D model, measures the impact on learning (in recalling the names of various components and their locations), and analyzes for user preferences in interacting with a 3D model on a mobile form factor at different zooming levels. Results of our study reflect that participants preferred external style annotations over internal and box style annotations, and that the participant’s performance (for both efficiency and accuracy) in searching for components inside a 3D model was highest with external style annotations. We also found that participants recalled more components when annotated with external styles annotations. Our findings suggest that of the three textual annotation styles considered in this study, external style annotation is the best annotation style to use in an annotated 3D model.
2

Impressions from Virtual Landscapes

McMasters, Neil G, neilgmcmasters@mac.com January 2003 (has links)
The aim of this project was to build and render digital landscape models that reflect natural element characteristics and use the resulting data sets as source material for fine art investigation and production. The project utilized 3D computer modeling techniques, selected output technology and studio facilities. Computer-generated virtual landscapes material was incorporated into studio practice by providing observed environmental content for the development of works for exhibition. An accompanying exegesis explored the relationship and tensions between digital landscape data sets and the broader use of landscape as a motif within an Australian context.
3

Δημιουργία 3D μοντέλων με χρήση 3D scanner και μέθοδοι ανάκτησης

Βλάχος, Απόστολος 09 March 2011 (has links)
Η εργασία αυτή εξηγεί την λειτουργία των 3D Scanners και την χρήση τους με σκοπό την δημιουργία τρισδιάστατων μοντέλων, καθώς και προτείνει μεθόδους ανάκτησης απο τις υπάρχουσες βάσεις δεδομένων 3D μοντέλων. / This project explains 3D Scanner basics and their use in order to create 3 dimensional models, as well as suggest retrieval methods from existing 3D model databases.
4

An Octree Surface Wrapping Algorithm to Recover Building Structures

Trcalek, Michal 15 December 2012 (has links)
In the past twenty years, our world has experienced a number of disasters, ranging from hurricanes to acts of terrorism. While both natural and anthropogenic disasters are inevitable, being able to simulate their progression and impact can provide guidance for preemptive measures to mitigate casualties and property damage. Specifically, computational fluid dynamics (CFD) simulations can be used to simulate wind forces associated with hurricanes or pressure waves associated with explosions. However, even a simple CFD simulation is time consuming and requires highly-specialized expertise. This paper aims to reduce the processing time by utilizing readily available geometry models, and a surface wrapping algorithm that allows for fast and seamless way of repairing geometry. Both of these processes are automated which also reduces the amount of training in various software packages.
5

Interactive Part Selection for Mesh and Point Models Using Hierarchical Graph-cut Partitioning

Brown, Steven W. 16 June 2008 (has links) (PDF)
This thesis presents a method for interactive part selection for mesh and point set surface models that combines scribble-based selection methods with hierarchically accelerated graph-cut segmentation. Using graph-cut segmentation to determine optimal intuitive part boundaries enables easy part selection on complex geometries and allows for a simple, scribble-based interface that focuses on selecting within visible parts instead of precisely defining part boundaries that may be in difficult or occluded regions. Hierarchical acceleration is used to maintain interactive speeds with large models and to determine connectivity when extending the technique to point set models.
6

Evaluating osteological ageing from digital data

Villa, C., Buckberry, Jo, Lynnerup, N. 13 September 2016 (has links)
Yes / Age at death estimation of human skeletal remains is one of the key issues in constructing a biological profile both in forensic and archaeological contexts. The traditional adult osteological methods evaluate macroscopically the morphological changes that occur with increasing age of specific skeletal indicators, such as the cranial sutures, the pubic bone, the auricular surface of the ilium and the sternal end of the ribs. Technologies such as CT and laser scanning are becoming more widely used in anthropology, and several new methods have been developed. This review focuses on how the osteological age-related changes have been evaluated in digital data. Firstly, the 3D virtual copies of the bones have been used to mimic the appearance of the dry bones and the application of the traditional methods. Secondly, the information directly extrapolated from CT scan has been used to qualitatively or quantitatively assess the changes of the trabecular bones, the thickness of the cortical bones, and to perform morphometric analyses. Lastly, the most innovative approach has been the mathematical quantification of the changes of the pelvic joints, calculating the complexity of the surface. The importance of new updated reference datasets, created thanks to the use of CT scanning in forensic settings, is also discussed. / CV was supported from the Danish Council for Independent Research (DFF – 4005-00102B – FTP)
7

Vehicle Tracking in Outdoor Environments using 3D Models

Nathalie, El Nabbout January 2008 (has links)
There has been a growth in demand for advancing algorithms in surveillance applications concerning moving vehicles where analysis of traffic has a potential application to security, traffic management (congestion and accident detection), speed measurement, car counting and statistics, as well as turning movement at intersections. This research focuses on multiple-vehicle detection, recognition, and tracking in urban environments based on video sequences obtained from a single CCD camera mounted on a pole at urban highways and crossroads. The proposed system integrates several modules including segmentation, object detection, object recognition and classification, and tracking. Background segmentation, based on Gaussian Mixture models, is used to extract moving objects from images using the respective foreground object information such as location, size, and color distribution. To recognize vehicles, a 3D polyhedral car model described by a set of parameters is built and mapped to the 2D edge information attained from the video sequence. The matching process is then used to classify the foreground object obtained into vehicles and non-vehicles. The output from the recognition model is used in tracking multiple cars based on a deterministic data association method that takes place between consecutive frame information. The multiple-vehicle surveillance system developed in this thesis, based on integrating different modules, provides a novel approach for vehicle monitoring. Furthermore, the system makes use of minimal a priori knowledge about vehicle location, size, type, numbers, and pathways. The system implemented in this work functions well under various camera perspectives, background clutter, vehicle viewpoints, road types, scale changes, image noise, image resolutions, and lighting conditions.
8

Vehicle Tracking in Outdoor Environments using 3D Models

Nathalie, El Nabbout January 2008 (has links)
There has been a growth in demand for advancing algorithms in surveillance applications concerning moving vehicles where analysis of traffic has a potential application to security, traffic management (congestion and accident detection), speed measurement, car counting and statistics, as well as turning movement at intersections. This research focuses on multiple-vehicle detection, recognition, and tracking in urban environments based on video sequences obtained from a single CCD camera mounted on a pole at urban highways and crossroads. The proposed system integrates several modules including segmentation, object detection, object recognition and classification, and tracking. Background segmentation, based on Gaussian Mixture models, is used to extract moving objects from images using the respective foreground object information such as location, size, and color distribution. To recognize vehicles, a 3D polyhedral car model described by a set of parameters is built and mapped to the 2D edge information attained from the video sequence. The matching process is then used to classify the foreground object obtained into vehicles and non-vehicles. The output from the recognition model is used in tracking multiple cars based on a deterministic data association method that takes place between consecutive frame information. The multiple-vehicle surveillance system developed in this thesis, based on integrating different modules, provides a novel approach for vehicle monitoring. Furthermore, the system makes use of minimal a priori knowledge about vehicle location, size, type, numbers, and pathways. The system implemented in this work functions well under various camera perspectives, background clutter, vehicle viewpoints, road types, scale changes, image noise, image resolutions, and lighting conditions.
9

A Comparative Study On Polygonal Mesh Simplification Algorithms

Yirci, Murat 01 September 2008 (has links) (PDF)
Polygonal meshes are a common way of representing 3D surface models in many different areas of computer graphics and geometry processing. However, these models are becoming more and more complex which increases the cost of processing these models. In order to reduce this cost, mesh simplification algorithms are developed. Another important property of a polygonal mesh model is that whether it is regular or not. Regular meshes have many advantages over the irregular ones in terms of memory requirements, efficient processing, rendering etc. In this thesis work, both mesh simplification and regular remeshing algorithms are studied. Moreover, some of the popular mesh libraries are compared with respect to their approaches and performance to the mesh simplification. In addition, mesh models with disk topology are remeshed and converted to regular ones.
10

Kompiuterinio automatizuoto projektavimo posistemė pastato sienoms su angomis formuoti / CAD subsystem for creating of the building's walls with the openings

Šliaužytė, Brigita 05 June 2006 (has links)
Many architects is working with AutoCAD system. But it is very time consuming work when it is needed to do such a work like drawing 3D models of walls with openings. This can be solved because of AutoCAD open architecture. Advantages of this would be less of errors in drawings and more time for other work for architects. Created software is able from 2D draft of lines make 3D walls and, if was chossed, openings. The user describes dimensions of wall and / or opening and the program will change selected line by set of planes with the opening inside. There are a few aviable options for user choise: openings may have a form of triangle or rectangular, walls maybe be like surfaces or lines, it is possible to create a wall with an array of rectangular openings, and delete already created walls leaving primary lines. For software creation was choosen Visual Basic for Aplication programing language because of it is object – oriented and easy comunication with standart AutoCAD’s classes and graphical objects. User‘s dialog’s form was choosen nearly these, what apear in such software like Architectural Desktop because of its logical simplicity. Supposing created software will be developed further in these ways: o Adding more opening’s shapes o Creating library of opening’s o Supporting all standarts needed for professional.

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