You limited your search to:

  Partner: UNT Libraries
 Degree Discipline: Computer Science
 Collection: UNT Theses and Dissertations
Multi-perspective, Multi-modal Image Registration and Fusion
Multi-modal image fusion is an active research area with many civilian and military applications. Fusion is defined as strategic combination of information collected by various sensors from different locations or different types in order to obtain a better understanding of an observed scene or situation. Fusion of multi-modal images cannot be completed unless these two modalities are spatially aligned. In this research, I consider two important problems. Multi-modal, multi-perspective image registration and decision level fusion of multi-modal images. In particular, LiDAR and visual imagery. Multi-modal image registration is a difficult task due to the different semantic interpretation of features extracted from each modality. This problem is decoupled into three sub-problems. The first step is identification and extraction of common features. The second step is the determination of corresponding points. The third step consists of determining the registration transformation parameters. Traditional registration methods use low level features such as lines and corners. Using these features require an extensive optimization search in order to determine the corresponding points. Many methods use global positioning systems (GPS), and a calibrated camera in order to obtain an initial estimate of the camera parameters. The advantages of our work over the previous works are the following. First, I used high level-features, which significantly reduce the search space for the optimization process. Second, the determination of corresponding points is modeled as an assignment problem between a small numbers of objects. On the other side, fusing LiDAR and visual images is beneficial, due to the different and rich characteristics of both modalities. LiDAR data contain 3D information, while images contain visual information. Developing a fusion technique that uses the characteristics of both modalities is very important. I establish a decision-level fusion technique using manifold models. digital.library.unt.edu/ark:/67531/metadc149562/
The Multipath Fault-Tolerant Protocol for Routing in Packet-Switched Communication Network
In order to provide improved service quality to applications, networks need to address the need for reliability of data delivery. Reliability can be improved by incorporating fault tolerance into network routing, wherein a set of multiple routes are used for routing between a given source and destination. This thesis proposes a new fault-tolerant protocol, called the Multipath Fault Tolerant Protocol for Routing (MFTPR), to improve the reliability of network routing services. The protocol is based on a multipath discovery algorithm, the Quasi-Shortest Multipath (QSMP), and is designed to work in conjunction with the routing protocol employed by the network. MFTPR improves upon the QSMP algorithm by finding more routes than QSMP, and also provides for maintenance of these routes in the event of failure of network components. In order to evaluate the resilience of a pair of paths to failure, this thesis proposes metrics that evaluate the non-disjointness of a pair of paths and measure the probability of simultaneous failure of these paths. The performance of MFTPR to find alternate routes based on these metrics is analyzed through simulation. digital.library.unt.edu/ark:/67531/metadc4199/
DICOM Image Scrubbing Software Library/Utility
This software is aimed at providing user-friendly, easy-to-use environment for the user to scrub (de-identify/modify) the DICOM header information. Some tools either anonymize or default the values without the user interaction. The user doesn't have the flexibility to edit the header information. One cannot scrub set of images simultaneously (batch scrubbing). This motivated to develop a tool/utility that can scrub a set of images in a single step more efficiently. This document also addresses security issues of the patient confidentiality to achieve protection of patient identifying information and some technical requirements digital.library.unt.edu/ark:/67531/metadc4189/
Study and Sample Implementation of the Secure Shell Protocol (SSH)
Access: Use of this item is restricted to the UNT Community.
Security is one of the main concerns of users who need to connect to a remote computer for various purposes, such as checking e-mails or viewing files. However in today's computer networks, privacy, transmission to intended client is not guaranteed. If data is transmitted over the Internet or a local network as plain text it may be captured and viewed by anyone with little technical knowledge. This may include sensitive data such as passwords. Big businesses use firewalls, virtual private networks and encrypt their transmissions to counter this at high costs. Secure shell protocol (SSH) provides an answer to this. SSH is a software protocol for secure communication over an insecure network. SSH not only offers authentication of hosts but also encrypts the sessions between the client and the server and is transparent to the end user. This Problem in Lieu of Thesis makes a study of SSH and creates a sample secure client and server which follows SSH and examines its performance. digital.library.unt.edu/ark:/67531/metadc4143/
Security problems in 802.11 wireless networks standard due to the inefficiency of wired equivalent privacy protocol.
Due to the rapid growth of wireless networking, the fallible security issues of the 802.11 standard have come under close scrutiny. Nowadays most of the organizations are eager to setup wireless local area networks to reduce the hassles of limited mobility provided by conventional wired network. There are serious security issues that need to be sorted out before everyone is willing to transmit valuable corporate information on a wireless network. This report documents the inherent flaws in wired equivalent privacy protocol used by the 802.11 standard and the ensuing security breaches that can occur to a wireless network due to these flaws. The solutions suggested in this report might not actually make the 802.11 standard secure, but will surely help in the lead up to a secure wireless network standard. digital.library.unt.edu/ark:/67531/metadc4182/
Higher Compression from the Burrows-Wheeler Transform with New Algorithms for the List Update Problem
Burrows-Wheeler compression is a three stage process in which the data is transformed with the Burrows-Wheeler Transform, then transformed with Move-To-Front, and finally encoded with an entropy coder. Move-To-Front, Transpose, and Frequency Count are some of the many algorithms used on the List Update problem. In 1985, Competitive Analysis first showed the superiority of Move-To-Front over Transpose and Frequency Count for the List Update problem with arbitrary data. Earlier studies due to Bitner assumed independent identically distributed data, and showed that while Move-To-Front adapts to a distribution faster, incurring less overwork, the asymptotic costs of Frequency Count and Transpose are less. The improvements to Burrows-Wheeler compression this work covers are increases in the amount, not speed, of compression. Best x of 2x-1 is a new family of algorithms created to improve on Move-To-Front's processing of the output of the Burrows-Wheeler Transform which is like piecewise independent identically distributed data. Other algorithms for both the middle stage of Burrows-Wheeler compression and the List Update problem for which overwork, asymptotic cost, and competitive ratios are also analyzed are several variations of Move One From Front and part of the randomized algorithm Timestamp. The Best x of 2x - 1 family includes Move-To-Front, the part of Timestamp of interest, and Frequency Count. Lastly, a greedy choosing scheme, Snake, switches back and forth as the amount of compression that two List Update algorithms achieves fluctuates, to increase overall compression. The Burrows-Wheeler Transform is based on sorting of contexts. The other improvements are better sorting orders, such as “aeioubcdf...” instead of standard alphabetical “abcdefghi...” on English text data, and an algorithm for computing orders for any data, and Gray code sorting instead of standard sorting. Both techniques lessen the overwork incurred by whatever List Update algorithms are used by reducing the difference between adjacent sorted contexts. digital.library.unt.edu/ark:/67531/metadc2909/
An Annotated Bibliography of Mobile Agents in Networks
The purpose of this thesis is to present a comprehensive colligation of applications of mobile agents in networks, and provide a baseline association of these systems. This work has been motivated by the fact that mobile agent systems have been deemed proficuous alternatives in system applications. Several mobile agent systems have been developed to provide scalable and cogent solutions in network-centric applications. This thesis examines some existing mobile agent systems in core networking areas, in particular, those of network and resource management, routing, and the provision of fault tolerance and security. The inherent features of these systems are discussed with respect to their specific functionalities. The applicability and efficacy of mobile agents are further considered in the specific areas mentioned above. Although an initial foray into a collation of this nature, the goal of this annotated bibliography is to provide a generic referential view of mobile agent systems in network applications. digital.library.unt.edu/ark:/67531/metadc3310/
Measuring Vital Signs Using Smart Phones
Smart phones today have become increasingly popular with the general public for its diverse abilities like navigation, social networking, and multimedia facilities to name a few. These phones are equipped with high end processors, high resolution cameras, built-in sensors like accelerometer, orientation-sensor, light-sensor, and much more. According to comScore survey, 25.3% of US adults use smart phones in their daily lives. Motivated by the capability of smart phones and their extensive usage, I focused on utilizing them for bio-medical applications. In this thesis, I present a new application for a smart phone to quantify the vital signs such as heart rate, respiratory rate and blood pressure with the help of its built-in sensors. Using the camera and a microphone, I have shown how the blood pressure and heart rate can be determined for a subject. People sometimes encounter minor situations like fainting or fatal accidents like car crash at unexpected times and places. It would be useful to have a device which can measure all vital signs in such an event. The second part of this thesis demonstrates a new mode of communication for next generation 9-1-1 calls. In this new architecture, the call-taker will be able to control the multimedia elements in the phone from a remote location. This would help the call-taker or first responder to have a better control over the situation. Transmission of the vital signs measured using the smart phone can be a life saver in critical situations. In today's voice oriented 9-1-1 calls, the dispatcher first collects critical information (e.g., location, call-back number) from caller, and assesses the situation. Meanwhile, the dispatchers constantly face a "60-second dilemma"; i.e., within 60 seconds, they need to make a complicated but important decision, whether to dispatch and, if so, what to dispatch. The dispatchers often feel that they lack sufficient information to make a confident dispatch decision. This remote-media-control described in this system will be able to facilitate information acquisition and decision-making in emergency situations within the 60-second response window in 9-1-1 calls using new multimedia technologies. digital.library.unt.edu/ark:/67531/metadc33139/
Anchor Nodes Placement for Effective Passive Localization
Access: Use of this item is restricted to the UNT Community.
Wireless sensor networks are composed of sensor nodes, which can monitor an environment and observe events of interest. These networks are applied in various fields including but not limited to environmental, industrial and habitat monitoring. In many applications, the exact location of the sensor nodes is unknown after deployment. Localization is a process used to find sensor node's positional coordinates, which is vital information. The localization is generally assisted by anchor nodes that are also sensor nodes but with known locations. Anchor nodes generally are expensive and need to be optimally placed for effective localization. Passive localization is one of the localization techniques where the sensor nodes silently listen to the global events like thunder sounds, seismic waves, lighting, etc. According to previous studies, the ideal location to place anchor nodes was on the perimeter of the sensor network. This may not be the case in passive localization, since the function of anchor nodes here is different than the anchor nodes used in other localization systems. I do extensive studies on positioning anchor nodes for effective localization. Several simulations are run in dense and sparse networks for proper positioning of anchor nodes. I show that, for effective passive localization, the optimal placement of the anchor nodes is at the center of the network in such a way that no three anchor nodes share linearity. The more the non-linearity, the better the localization. The localization for our network design proves better when I place anchor nodes at right angles. digital.library.unt.edu/ark:/67531/metadc33132/
Agent-based architecture for web deployment of multi-agents as conversational interfaces.
Agent-based architecture explains the rationale and basis for developing agents that can interact with users through natural language query/answer patterns developed systematically using AIML (artificial intelligence mark-up language) scripts. This thesis research document also explains the architecture for VISTA (virtual interactive story-telling agents), which is used for interactive querying in educational and recreational purposes. Agents are very effective as conversational interfaces when used along side with graphical user interface (GUI) in applications and Web pages. This architecture platform can support multiple agents with or with out sharing of knowledgebase. They are very useful as chat robots for recreational purposes, customer service and educational purposes. This platform is powered by Java servlet implementation of Program D and contained in Apache Tomcat server. The AIML scripting language defined here in is a generic form of XML language and forms the knowledgebase of the bot. Animation is provided with Microsoft® Agent technology and text-to-speech support engine. digital.library.unt.edu/ark:/67531/metadc4187/
Self-Optimizing Dynamic Finite Functions
Access: Use of this item is restricted to the UNT Community.
Finite functions (also called maps) are used to describe a number of key computations and storage mechanisms used in software and hardware interpreters. Their presence spread over various memory and speed hierarchies in hardware and through various optimization processes (algorithmic and compilation based) in software, suggests encapsulating dynamic size changes and representation optimizations in a unique abstraction to be used across traditional computation mechanisms. We developed a memory allocator for testing the finite functions. We have implemented some dynamic finite functions and performed certain experiments to see the performance speed of these finite functions. We have developed some simple but powerful application programming interfaces (API) for these finite functions. digital.library.unt.edu/ark:/67531/metadc4364/
Machine Language Techniques for Conversational Agents
Machine Learning is the ability of a machine to perform better at a given task, using its previous experience. Various algorithms like decision trees, Bayesian learning, artificial neural networks and instance-based learning algorithms are used widely in machine learning systems. Current applications of machine learning include credit card fraud detection, customer service based on history of purchased products, games and many more. The application of machine learning techniques to natural language processing (NLP) has increased tremendously in recent years. Examples are handwriting recognition and speech recognition. The problem we tackle in this Problem in Lieu of Thesis is applying machine-learning techniques to improve the performance of a conversational agent. The OpenMind repository of common sense, in the form of question-answer pairs is treated as the training data for the machine learning system. WordNet is interfaced with to capture important semantic and syntactic information about the words in the sentences. Further, k-closest neighbors algorithm, an instance based learning algorithm is used to simulate a case based learning system. The resulting system is expected to be able to answer new queries with knowledge gained from the training data it was fed with. digital.library.unt.edu/ark:/67531/metadc4385/
Automated defense against worm propagation.
Access: Use of this item is restricted to the UNT Community.
Worms have caused significant destruction over the last few years. Network security elements such as firewalls, IDS, etc have been ineffective against worms. Some worms are so fast that a manual intervention is not possible. This brings in the need for a stronger security architecture which can automatically react to stop worm propagation. The method has to be signature independent so that it can stop new worms. In this thesis, an automated defense system (ADS) is developed to automate defense against worms and contain the worm to a level where manual intervention is possible. This is accomplished with a two level architecture with feedback at each level. The inner loop is based on control system theory and uses the properties of PID (proportional, integral and differential controller). The outer loop works at the network level and stops the worm to reach its spread saturation point. In our lab setup, we verified that with only inner loop active the worm was delayed, and with both loops active we were able to restrict the propagation to 10% of the targeted hosts. One concern for deployment of a worm containment mechanism was degradation of throughput for legitimate traffic. We found that with proper intelligent algorithm we can minimize the degradation to an acceptable level. digital.library.unt.edu/ark:/67531/metadc4909/
Modeling Complex Forest Ecology in a Parallel Computing Infrastructure
Effective stewardship of forest ecosystems make it imperative to measure, monitor, and predict the dynamic changes of forest ecology. Measuring and monitoring provides us a picture of a forest's current state and the necessary data to formulate models for prediction. However, societal and natural events alter the course of a forest's development. A simulation environment that takes into account these events will facilitate forest management. In this thesis, we describe an efficient parallel implementation of a land cover use model, Mosaic, and discuss the development efforts to incorporate spatial interaction and succession dynamics into the model. To evaluate the performance of our implementation, an extensive set of simulation experiments was carried out using a dataset representing the H.J. Andrews Forest in the Oregon Cascades. Results indicate that a significant reduction in the simulation execution time of our parallel model can be achieved as compared to uni-processor simulations. digital.library.unt.edu/ark:/67531/metadc4305/
Web Services for Libraries
Access: Use of this item is restricted to the UNT Community.
Library information systems use different software applications and automated systems to gain access to distributed information. Rapid application development, changes made to existing software applications and development of new software on different platforms can make it difficult for library information systems to interoperate. Web services are used to offer better information access and retrieval solutions and hence make it more cost effective for libraries. This research focuses on how web services are implemented with the standard protocols like SOAP, WSDL and UDDI using different programming languages and platforms to achieve interoperability for libraries. It also shows how libraries can make use of this new technology. Since web services built on different platforms can interact with each other, libraries can access information with more efficiency and flexibility. digital.library.unt.edu/ark:/67531/metadc4361/
Implementation of Back Up Host in TCP/IP
Access: Use of this item is restricted to the UNT Community.
This problem in lieu thesis is considering a TCP client H1 making a connection to distant server S and is downloading a file. In the midst of the downloading, if H1 crashes, the TCP connection from H1 to S is lost. In the future, if H1 restarts, the TCP connection from H1 to S will be reestablished and the file will be downloaded again. This cannot happen until host H1 restarts. Now consider a situation where there is a standby host H2 for the host H1. H1 and H2 monitor the health of each other by heartbeat messages (like SCTP). If H2 detects the failure of H1, then H2 takes over. This implies that all resources assigned to H1 are now reassigned or taken over by H2. The host H1 and H2 transmit data between each other when any one of it crashed. Throughout the data transmission process, heart beat chunk is exchanged between the hosts when one of the host crashes. In particular, the IP addresses that were originally assigned to H1 are assigned to H2. In this scenario, movement of the TCP connection between H1 and S to a connection between H2 and S without disrupting the TCP connection is achieved. Distant server S is not aware of any changes going on at the clients. digital.library.unt.edu/ark:/67531/metadc3288/
Performance Evaluation of MPLS on Quality of Service in Voice Over IP (VoIP) Networks
Access: Use of this item is restricted to the UNT Community.
The transmission of voice data over Internet Protocol (IP) networks is rapidly gaining acceptance in the field of networking. The major voice transmissions in the IP networks are involved in Internet telephony, which is also known as IP telephony or Voice Over IP (VoIP). VoIP is undergoing many enhancements to provide the end users with same quality as in the public switched telephone networks (PSTN). These enhancements are mostly required in quality of service (QoS) for the transmission of voice data over the IP networks. As with recent developments in the networking field, various protocols came into market to provide the QoS in IP networks - of them, multi protocol label switching (MPLS) is the most reliable and upcoming protocol for working on QoS. The problem of the thesis is to develop an IP-based virtual network, with end hosts and routers, implement MPLS on the network, and analyze its QoS for voice data transmission. digital.library.unt.edu/ark:/67531/metadc3293/
Refactoring FrameNet for Efficient Relational Queries
The FrameNet database is being used in a variety of NLP research and applications such as word sense disambiguation, machine translation, information extraction and question answering. The database is currently available in XML format. The XML database though a wholesome way of distributing data in its entireness, is not practical for use unless converted to a more application friendly database. In light of this we have successfully converted the XML database to a relational MySQL™ database. This conversion reduced the amount of data storage amount to less than half. Most importantly the new database enables us to perform fast complex querying and facilitates use by applications and research. We show the steps taken to ensure relational integrity of the data during the refactoring process and a simple demo application demonstrating ease of use. digital.library.unt.edu/ark:/67531/metadc4443/
Secret Key Agreement without Public-Key Cryptography
Access: Use of this item is restricted to the UNT Community.
Secure communication is the primary challenge in today's information network. In this project an efficient secret key agreement protocol is described and analyzed along with the other existing protocols. We focus primarily on Leighton and Micali's secret-key agreement without the use of public-key encryption techniques. The Leighton-Micali protocol is extremely efficient when implemented in software and has significant advantages over existing systems like Kerberos. In this method the secret keys are agreed upon using a trusted third party known as the trusted agent. The trusted agent generates the keys and writes them to a public directory before it goes offline. The communicating entities can retrieve the keys either from the online trusted agent or from the public directory service and agree upon a symmetric-key without any public-key procedures. The principal advantage of this method is that the user verifies the authenticity of the trusted agent before using the keys generated by it. The Leighton-Micali scheme is not vulnerable to the present day attacks like fabrication, modification or denial of service etc. The Leighton-Micali protocol can be employed in real-time systems like smart cards. In addition to the security properties and the simplicity of the protocol, our experiments show that in practice the time to generate keys is very low, and is faster than the Diffie-Hellman key exchange for the same problem. digital.library.unt.edu/ark:/67531/metadc4249/
Content-based image retrieval by integration of metadata encoded multimedia (image and text) features in constructing a video summarizer application.
Content-based image retrieval (CBIR) is the retrieval of images from a collection by means of internal feature measures of the information content of the images. In CBIR systems, text media is usually used only to retrieve exemplar images for further searching by image feature content. This research work describes a new method for integrating multimedia text and image content features to increase the retrieval performance of the system. I am exploring the content-based features of an image extracted from a video to build a storyboard for search retrieval of images. Metadata encoded multimedia features include extracting primitive features like color, shape and text from an image. Histograms are built for all the features extracted and stored in a database. Images are searched based on comparing these histogram values of the extracted image with the stored values. These histogram values are used for extraction of keyframes from a collection of images parsed from a video file. Individual shots of images are extracted from a video clip and run through processes that extract the features and build the histogram values. A keyframe extraction algorithm is run to get the keyframes from the collection of images to build a storyboard of images. In video retrieval, speech recognition and other multimedia encoding could help improve the CBIR indexing technique and makes keyframe extraction and searching effective. Research in area of embedding sound and other multimedia could enhance effective video retrieval. digital.library.unt.edu/ark:/67531/metadc4238/
System and Methods for Detecting Unwanted Voice Calls
Voice over IP (VoIP) is a key enabling technology for the migration of circuit-switched PSTN architectures to packet-based IP networks. However, this migration is successful only if the present problems in IP networks are addressed before deploying VoIP infrastructure on a large scale. One of the important issues that the present VoIP networks face is the problem of unwanted calls commonly referred to as SPIT (spam over Internet telephony). Mostly, these SPIT calls are from unknown callers who broadcast unwanted calls. There may be unwanted calls from legitimate and known people too. In this case, the unwantedness depends on social proximity of the communicating parties. For detecting these unwanted calls, I propose a framework that analyzes incoming calls for unwanted behavior. The framework includes a VoIP spam detector (VSD) that analyzes incoming VoIP calls for spam behavior using trust and reputation techniques. The framework also includes a nuisance detector (ND) that proactively infers the nuisance (or reluctance of the end user) to receive incoming calls. This inference is based on past mutual behavior between the calling and the called party (i.e., caller and callee), the callee's presence (mood or state of mind) and tolerance in receiving voice calls from the caller, and the social closeness between the caller and the callee. The VSD and ND learn the behavior of callers over time and estimate the possibility of the call to be unwanted based on predetermined thresholds configured by the callee (or the filter administrators). These threshold values have to be automatically updated for integrating dynamic behavioral changes of the communicating parties. For updating these threshold values, I propose an automatic calibration mechanism using receiver operating characteristics curves (ROC). The VSD and ND use this mechanism for dynamically updating thresholds for optimizing their accuracy of detection. In addition to unwanted calls to the callees in a VoIP network, there can be unwanted traffic coming into a VoIP network that attempts to compromise VoIP network devices. Intelligent hackers can create malicious VoIP traffic for disrupting network activities. Hence, there is a need to frequently monitor the risk levels of critical network infrastructure. Towards realizing this objective, I describe a network level risk management mechanism that prioritizes resources in a VoIP network. The prioritization scheme involves an adaptive re-computation model of risk levels using attack graphs and Bayesian inference techniques. All the above techniques collectively account for a domain-level VoIP security solution. digital.library.unt.edu/ark:/67531/metadc5155/
Web-based airline ticket booking system.
Online airline ticket booking system is one of the essential applications of E-commerce. With the development of Internet and security technology, more and more people begin to consume online, which is more convenient and personal than traditional way. The goal of this system is to make people purchase airline tickets easily. The system is written in JAVATM. Chapter 1 will introduce some basic conception of the technologies have been used in this system. Chapter 2 shows how the database and the system are designed. Chapter 3 shows the logic of the Web site. In Chapter 4 the interface of the system will be given. Chapter 5 tells the platform of this system. digital.library.unt.edu/ark:/67531/metadc4556/
Logic Programming Tools for Dynamic Content Generation and Internet Data Mining
Access: Use of this item is restricted to the UNT Community.
The phenomenal growth of Information Technology requires us to elicit, store and maintain huge volumes of data. Analyzing this data for various purposes is becoming increasingly important. Data mining consists of applying data analysis and discovery algorithms that under acceptable computational efficiency limitations, produce a particular enumeration of patterns over the data. We present two techniques based on using Logic programming tools for data mining. Data mining analyzes data by extracting patterns which describe its structure and discovers co-relations in the form of rules. We distinguish analysis methods as visual and non-visual and present one application of each. We explain that our focus on the field of Logic Programming makes some of the very complex tasks related to Web based data mining and dynamic content generation, simple and easy to implement in a uniform framework. digital.library.unt.edu/ark:/67531/metadc2677/
Dynamic Grid-Based Data Distribution Management in Large Scale Distributed Simulations
Distributed simulation is an enabling concept to support the networked interaction of models and real world elements that are geographically distributed. This technology has brought a new set of challenging problems to solve, such as Data Distribution Management (DDM). The aim of DDM is to limit and control the volume of the data exchanged during a distributed simulation, and reduce the processing requirements of the simulation hosts by relaying events and state information only to those applications that require them. In this thesis, we propose a new DDM scheme, which we refer to as dynamic grid-based DDM. A lightweight UNT-RTI has been developed and implemented to investigate the performance of our DDM scheme. Our results clearly indicate that our scheme is scalable and it significantly reduces both the number of multicast groups used, and the message overhead, when compared to previous grid-based allocation schemes using large-scale and real-world scenarios. digital.library.unt.edu/ark:/67531/metadc2699/
Hopfield Networks as an Error Correcting Technique for Speech Recognition
Access: Use of this item is restricted to the UNT Community.
I experimented with Hopfield networks in the context of a voice-based, query-answering system. Hopfield networks are used to store and retrieve patterns. I used this technique to store queries represented as natural language sentences and I evaluated the accuracy of the technique for error correction in a spoken question-answering dialog between a computer and a user. I show that the use of an auto-associative Hopfield network helps make the speech recognition system more fault tolerant. I also looked at the available encoding schemes to convert a natural language sentence into a pattern of zeroes and ones that can be stored in the Hopfield network reliably, and I suggest scalable data representations which allow storing a large number of queries. digital.library.unt.edu/ark:/67531/metadc5551/
Mobile agent security through multi-agent cryptographic protocols.
An increasingly promising and widespread topic of research in distributed computing is the mobile agent paradigm: code travelling and performing computations on remote hosts in an autonomous manner. One of the biggest challenges faced by this new paradigm is security. The issue of protecting sensitive code and data carried by a mobile agent against tampering from a malicious host is particularly hard but important. Based on secure multi-party computation, a recent research direction shows the feasibility of a software-only solution to this problem, which had been deemed impossible by some researchers previously. The best result prior to this dissertation is a single-agent protocol which requires the participation of a trusted third party. Our research employs multi-agent protocols to eliminate the trusted third party, resulting in a protocol with minimum trust assumptions. This dissertation presents one of the first formal definitions of secure mobile agent computation, in which the privacy and integrity of the agent code and data as well as the data provided by the host are all protected. We present secure protocols for mobile agent computation against static, semi-honest or malicious adversaries without relying on any third party or trusting any specific participant in the system. The security of our protocols is formally proven through standard proof technique and according to our formal definition of security. Our second result is a more practical agent protocol with strong security against most real-world host attacks. The security features are carefully analyzed, and the practicality is demonstrated through implementation and experimental study on a real-world mobile agent platform. All these protocols rely heavily on well-established cryptographic primitives, such as encrypted circuits, threshold decryption, and oblivious transfer. Our study of these tools yields new contributions to the general field of cryptography. Particularly, we correct a well-known construction of the encrypted circuit and give one of the first provably secure implementations of the encrypted circuit. digital.library.unt.edu/ark:/67531/metadc4473/
Case-Based Reasoning (CBR) for Children Story Selection in ASP.NET and C#
This paper describes the general architecture and function of a Case-Based Reasoning (CBR) system implemented with ASP.NET and C#. Microsoft Visual Studio .NET and XML Web Services provide a flexible, standards-based model that allows clients to access data. Web Form Pages offer a powerful programming model for Web-enabled user interface. The system provides a variety of mechanisms and services related to story retrieval and adaptation. Users may browse and search a library of text stories. More advanced CBR capabilities were also implemented, including a multi-factor distance-calculation for matching user interests with stories in the library, recommendations on optimizing search, and adaptation of stories to match user interests. digital.library.unt.edu/ark:/67531/metadc4417/
Voting Operating System (VOS)
Access: Use of this item is restricted to the UNT Community.
The electronic voting machine (EVM) plays a very important role in a country where government officials are elected into office. Throughout the world, a specific operating system that tends to the specific requirement of the EVM does not exist. Existing EVM technology depends upon the various operating systems currently available, thus ignoring the basic needs of the system. There is a compromise over the basic requirements in order to develop the systems on the basis on an already available operating system, thus having a lot of scope for error. It is necessary to know the specific details of the particular device for which the operating system is being developed. In this document, I evaluate existing EVMs and identify flaws and shortcomings. I propose a solution for a new operating system that meets the specific requirements of the EVM, calling it Voting Operating System (VOS, pronounced 'voice'). The identification technique can be simplified by using the fingerprint technology that determines the identity of a person based on two fingerprints. I also discuss the various parts of the operating system that have to be implemented that can tend to all the basic requirements of an EVM, including implementation of the memory manager, process manager and file system of the proposed operating system. digital.library.unt.edu/ark:/67531/metadc4648/
Exploring Trusted Platform Module Capabilities: A Theoretical and Experimental Study
Trusted platform modules (TPMs) are hardware modules that are bound to a computer's motherboard, that are being included in many desktops and laptops. Augmenting computers with these hardware modules adds powerful functionality in distributed settings, allowing us to reason about the security of these systems in new ways. In this dissertation, I study the functionality of TPMs from a theoretical as well as an experimental perspective. On the theoretical front, I leverage various features of TPMs to construct applications like random oracles that are impossible to implement in a standard model of computation. Apart from random oracles, I construct a new cryptographic primitive which is basically a non-interactive form of the standard cryptographic primitive of oblivious transfer. I apply this new primitive to secure mobile agent computations, where interaction between various entities is typically required to ensure security. I prove these constructions are secure using standard cryptographic techniques and assumptions. To test the practicability of these constructions and their applications, I performed an experimental study, both on an actual TPM and a software TPM simulator which has been enhanced to make it reflect timings from a real TPM. This allowed me to benchmark the performance of the applications and test the feasibility of the proposed extensions to standard TPMs. My tests also show that these constructions are practical. digital.library.unt.edu/ark:/67531/metadc6101/
Multi-Agent Architecture for Internet Information Extraction and Visualization
Access: Use of this item is restricted to the UNT Community.
The World Wide Web is one of the largest sources of information; more and more applications are being developed daily to make use of this information. This thesis presents a multi-agent architecture that deals with some of the issues related to Internet data extraction. The primary issue addresses the reliable, efficient and quick extraction of data through the use of HTTP performance monitoring agents. A second issue focuses on how to make use of available data to take decisions and alert the user when there is change in data; this is done with the help of user agents that are equipped with a Defeasible reasoning interpreter. An additional issue is the visualization of extracted data; this is done with the aid of VRML visualization agents. The cited issues are discussed using stock portfolio management as an example application. digital.library.unt.edu/ark:/67531/metadc2575/
Memory Management and Garbage Collection Algorithms for Java-Based Prolog
Access: Use of this item is restricted to the UNT Community.
Implementing a Prolog Runtime System in a language like Java which provides its own automatic memory management and safety features such as built--in index checking and array initialization requires a consistent approach to memory management based on a simple ultimate goal: minimizing total memory management time and extra space involved. The total memory management time for Jinni is made up of garbage collection time both for Java and Jinni itself. Extra space is usually requested at Jinni's garbage collection. This goal motivates us to find a simple and practical garbage collection algorithm and implementation for our Prolog engine. In this thesis we survey various algorithms already proposed and offer our own contribution to the study of garbage collection by improvements and optimizations for some classic algorithms. We implemented these algorithms based on the dynamic array algorithm for an all--dynamic Prolog engine (JINNI 2000). The comparisons of our implementations versus the originally proposed algorithm allow us to draw informative conclusions on their theoretical complexity model and their empirical effectiveness. digital.library.unt.edu/ark:/67531/metadc2825/
Flexible Digital Authentication Techniques
Abstract This dissertation investigates authentication techniques in some emerging areas. Specifically, authentication schemes have been proposed that are well-suited for embedded systems, and privacy-respecting pay Web sites. With embedded systems, a person could own several devices which are capable of communication and interaction, but these devices use embedded processors whose computational capabilities are limited as compared to desktop computers. Examples of this scenario include entertainment devices or appliances owned by a consumer, multiple control and sensor systems in an automobile or airplane, and environmental controls in a building. An efficient public key cryptosystem has been devised, which provides a complete solution to an embedded system, including protocols for authentication, authenticated key exchange, encryption, and revocation. The new construction is especially suitable for the devices with constrained computing capabilities and resources. Compared with other available authentication schemes, such as X.509, identity-based encryption, etc, the new construction provides unique features such as simplicity, efficiency, forward secrecy, and an efficient re-keying mechanism. In the application scenario for a pay Web site, users may be sensitive about their privacy, and do not wish their behaviors to be tracked by Web sites. Thus, an anonymous authentication scheme is desirable in this case. That is, a user can prove his/her authenticity without revealing his/her identity. On the other hand, the Web site owner would like to prevent a bunch of users from sharing a single subscription while hiding behind user anonymity. The Web site should be able to detect these possible malicious behaviors, and exclude corrupted users from future service. This dissertation extensively discusses anonymous authentication techniques, such as group signature, direct anonymous attestation, and traceable signature. Three anonymous authentication schemes have been proposed, which include a group signature scheme with signature claiming and variable linkability, a scheme for direct anonymous attestation in trusted computing platforms with sign and verify protocols nearly seven times more efficient than the current solution, and a state-of-the-art traceable signature scheme with support for variable anonymity. These three schemes greatly advance research in the area of anonymous authentication. The authentication techniques presented in this dissertation are based on common mathematical and cryptographical foundations, sharing similar security assumptions. We call them flexible digital authentication schemes. digital.library.unt.edu/ark:/67531/metadc5277/
A Language and Visual Interface to Specify Complex Spatial Pattern Mining
Access: Use of this item is restricted to the UNT Community.
The emerging interests in spatial pattern mining leads to the demand for a flexible spatial pattern mining language, on which easy to use and understand visual pattern language could be built. It is worthwhile to define a pattern mining language called LCSPM to allow users to specify complex spatial patterns. I describe a proposed pattern mining language in this paper. A visual interface which allows users to specify the patterns visually is developed. Visual pattern queries are translated into the LCSPM language by a parser and data mining process can be triggered afterwards. The visual language is based on and goes beyond the visual language proposed in literature. I implemented a prototype system based on the open source JUMP framework. digital.library.unt.edu/ark:/67531/metadc5408/
A Multi-Variate Analysis of SMTP Paths and Relays to Restrict Spam and Phishing Attacks in Emails
Access: Use of this item is restricted to the UNT Community.
The classifier discussed in this thesis considers the path traversed by an email (instead of its content) and reputation of the relays, features inaccessible to spammers. Groups of spammers and individual behaviors of a spammer in a given domain were analyzed to yield association patterns, which were then used to identify similar spammers. Unsolicited and phishing emails were successfully isolated from legitimate emails, using analysis results. Spammers and phishers are also categorized into serial spammers/phishers, recent spammers/phishers, prospective spammers/phishers, and suspects. Legitimate emails and trusted domains are classified into socially close (family members, friends), socially distinct (strangers etc), and opt-outs (resolved false positives and false negatives). Overall this classifier resulted in far less false positives when compared to current filters like SpamAssassin, achieving a 98.65% precision, which is well comparable to the precisions achieved by SPF, DNSRBL blacklists. digital.library.unt.edu/ark:/67531/metadc5402/
Modeling Infectious Disease Spread Using Global Stochastic Field Simulation
Susceptibles-infectives-removals (SIR) and its derivatives are the classic mathematical models for the study of infectious diseases in epidemiology. In order to model and simulate epidemics of an infectious disease, a global stochastic field simulation paradigm (GSFS) is proposed, which incorporates geographic and demographic based interactions. The interaction measure between regions is a function of population density and geographical distance, and has been extended to include demographic and migratory constraints. The progression of diseases using GSFS is analyzed, and similar behavior to the SIR model is exhibited by GSFS, using the geographic information systems (GIS) gravity model for interactions. The limitations of the SIR and similar models of homogeneous population with uniform mixing are addressed by the GSFS model. The GSFS model is oriented to heterogeneous population, and can incorporate interactions based on geography, demography, environment and migration patterns. The progression of diseases can be modeled at higher levels of fidelity using the GSFS model, and facilitates optimal deployment of public health resources for prevention, control and surveillance of infectious diseases. digital.library.unt.edu/ark:/67531/metadc5335/
A Study of Perceptually Tuned, Wavelet Based, Rate Scalable, Image and Video Compression
Access: Use of this item is restricted to the UNT Community.
In this dissertation, first, we have proposed and implemented a new perceptually tuned wavelet based, rate scalable, and color image encoding/decoding system based on the human perceptual model. It is based on state-of-the-art research on embedded wavelet image compression technique, Contrast Sensitivity Function (CSF) for Human Visual System (HVS) and extends this scheme to handle optimal bit allocation among multiple bands, such as Y, Cb, and Cr. Our experimental image codec shows very exciting results in compression performance and visual quality comparing to the new wavelet based international still image compression standard - JPEG 2000. On the other hand, our codec also shows significant better speed performance and comparable visual quality in comparison to the best codec available in rate scalable color image compression - CSPIHT that is based on Set Partition In Hierarchical Tree (SPIHT) and Karhunen-Loeve Transform (KLT). Secondly, a novel wavelet based interframe compression scheme has been developed and put into practice. It is based on the Flexible Block Wavelet Transform (FBWT) that we have developed. FBWT based interframe compression is very efficient in both compression and speed performance. The compression performance of our video codec is compared with H263+. At the same bit rate, our encoder, being comparable to the H263+ scheme, with a slightly lower (Peak Signal Noise Ratio (PSNR) value, produces a more visually pleasing result. This implementation also preserves scalability of wavelet embedded coding technique. Thirdly, the scheme to handle optimal bit allocation among color bands for still imagery has been modified and extended to accommodate the spatial-temporal sensitivity of the HVS model. The bit allocation among color bands based on Kelly's spatio-temporal CSF model is designed to achieve the perceptual optimum for human eyes. A perceptually tuned, wavelet based, rate scalable video encoding/decoding system has been designed and implemented based on this new bit allocation scheme. Finally to present the potential applications of our rate scalable video codec, a prototype system for rate scalable video streaming over the Internet has been designed and implemented to deal with the bandwidth unpredictability of the Internet. digital.library.unt.edu/ark:/67531/metadc3074/
The Feasibility of Multicasting in RMI
Due to the growing need of the Internet and networking technologies, simple, powerful, easily maintained distributed applications needed to be developed. These kinds of applications can benefit greatly from distributed computing concepts. Despite its powerful mechanisms, Jini has yet to be accepted in mainstream Java development. Until that happens, we need to find better Remote Method Invocation (RMI) solutions. Feasibility of implementation of Multicasting in RMI is worked in this paper. Multicasting capability can be used in RMI using Jini-like technique. Support of Multicast over Unicast reference layer is also studied. A piece of code explaining how it can be done, is added. digital.library.unt.edu/ark:/67531/metadc4170/
User Modeling Tools for Virtual Architecture
As the use of virtual environments (VEs) is becoming more widespread, user needs are becoming a more significant part in those environments. In order to adapt to the needs of the user, a system should be able to infer user interests and goals. I developed an architecture for user modeling to understand users' interests in a VE by monitoring their actions. In this paper, I discussed the architecture and the virtual environment that was created to test it. This architecture employs sensors to keep track of all the users' actions, data structures that can store a record of significant events that have occurred in the environment, and a rule base. The rule base continually monitors the data collected from the sensors, world state, and event history in order to update the user goal inferences. These inferences can then be used to modify the flow of events within a VE. digital.library.unt.edu/ark:/67531/metadc4169/
Developing a Test Bed for Interactive Narrative in Virtual Environments
Access: Use of this item is restricted to the UNT Community.
As Virtual Environments (VE) become a more commonly used method of interaction and presentation, supporting users as they navigate and interact with scenarios presented in VE will be a significant issue. A key step in understanding the needs of users in these situations will be observing them perform representative tasks in a fully developed environment. In this paper, we describe the development of a test bed for interactive narrative in a virtual environment. The test bed was specifically developed to present multiple, simultaneous sequences of events (scenarios or narratives) and to support user navigation through these scenarios. These capabilities will support the development of multiple users testing scenarios, allowing us to study and better understand the needs of users of narrative VEs. digital.library.unt.edu/ark:/67531/metadc3176/
Automatic Software Test Data Generation
Access: Use of this item is restricted to the UNT Community.
In software testing, it is often desirable to find test inputs that exercise specific program features. Finding these inputs manually, is extremely time consuming, especially, when the software being tested is complex. Therefore, there have been numerous attempts automate this process. Random test data generation consists of generating test inputs at random, in the hope that they will exercise the desired software features. Often the desired inputs must satisfy complex constraints, and this makes a random approach seem unlikely to succeed. In contrast, combinatorial optimization techniques, such as those using genetic algorithms, are meant to solve difficult problems involving simultaneous satisfaction of many constraints. digital.library.unt.edu/ark:/67531/metadc3276/
Visualization of Surfaces and 3D Vector Fields
Visualization of trivariate functions and vector fields with three components in scientific computation is still a hard problem in compute graphic area. People build their own visualization packages for their special purposes. And there exist some general-purpose packages (MatLab, Vis5D), but they all require extensive user experience on setting all the parameters in order to generate images. We present a simple package to produce simplified but productive images of 3-D vector fields. We used this method to render the magnetic field and current as solutions of the Ginzburg-Landau equations on a 3-D domain. digital.library.unt.edu/ark:/67531/metadc3235/
Ensuring Authenticity and Integrity of Critical Information Using XML Digital Signatures
Access: Use of this item is restricted to the UNT Community.
It has been noticed in the past five years that the Internet use has been troubled by the lack of sufficient security and a legal framework to enable electronic commerce to flourish. Despite these shortcomings, governments, businesses and individuals are using the Internet more often as an inexpensive and ubiquitous means to disseminate and obtain information, goods and services. The Internet is insecure -- potentially millions of people have access, and "hackers" can intercept anything traveling over the wire. There is no way to make it a secure environment; it is, after all, a public network, hence the availability and affordability. In order for it to serve our purposes as a vehicle for legally binding transactions, efforts must be directed at securing the message itself, as opposed to the transport mechanism. Digital signatures have been evolved in the recent years as the best tool for ensuring the authenticity and integrity of critical information in the so called "paperless office". A model using XML digital signatures is developed and the level of security provided by this model in the real world scenario is outlined. digital.library.unt.edu/ark:/67531/metadc3282/
Control mechanisms and recovery techniques for real-time data transmission over the Internet.
Streaming multimedia content with UDP has become popular over distributed systems such as an Internet. This may encounter many losses due to dropped packets or late arrivals at destination since UDP can only provide best effort delivery. Even UDP doesn't have any self-recovery mechanism from congestion collapse or bursty loss to inform sender of the data to adjust future transmission rate of data like in TCP. So there is a need to incorporate various control schemes like forward error control, interleaving, and congestion control and error concealment into real-time transmission to prevent from effect of losses. Loss can be repaired by retransmission if roundtrip delay is allowed, otherwise error concealment techniques will be used based on the type and amount of loss. This paper implements the interleaving technique with packet spacing of varying interleaver block size for protecting real-time data from loss and its effect during transformation across the Internet. The packets are interleaved and maintain some time gap between two consecutive packets before being transmitted into the Internet. Thus loss of packets can be reduced from congestion and preventing loss of consecutive packets of information when a burst of several packets are lost. Several experiments have been conducted with video data for analysis of proposed model. digital.library.unt.edu/ark:/67531/metadc3268/
Evaluation of MPLS Enabled Networks
Access: Use of this item is restricted to the UNT Community.
Recent developments in the Internet have inspired a wide range of business and consumer applications. The deployment of multimedia-based services has driven the demand for increased and guaranteed bandwidth requirements over the network. The diverse requirements of the wide range of users demand differentiated classes of service and quality assurance. The new technology of Multi-protocol label switching (MPLS) has emerged as a high performance and reliable option to address these challenges apart from the additional features that were not addressed before. This problem in lieu of thesis describes how the new paradigm of MPLS is advantageous over the conventional architecture. The motivation for this paradigm is discussed in the first part, followed by a detailed description of this new architecture. The information flow, the underlying protocols and the MPLS extensions to some of the traditional protocols are then discussed followed by the description of the simulation. The simulation results are used to show the advantages of the proposed technology. digital.library.unt.edu/ark:/67531/metadc5797/
Temporally Correct Algorithms for Transaction Concurrency Control in Distributed Databases
Access: Use of this item is restricted to the UNT Community.
Many activities are comprised of temporally dependent events that must be executed in a specific chronological order. Supportive software applications must preserve these temporal dependencies. Whenever the processing of this type of an application includes transactions submitted to a database that is shared with other such applications, the transaction concurrency control mechanisms within the database must also preserve the temporal dependencies. A basis for preserving temporal dependencies is established by using (within the applications and databases) real-time timestamps to identify and order events and transactions. The use of optimistic approaches to transaction concurrency control can be undesirable in such situations, as they allow incorrect results for database read operations. Although the incorrectness is detected prior to transaction committal and the corresponding transaction(s) restarted, the impact on the application or entity that submitted the transaction can be too costly. Three transaction concurrency control algorithms are proposed in this dissertation. These algorithms are based on timestamp ordering, and are designed to preserve temporal dependencies existing among data-dependent transactions. The algorithms produce execution schedules that are equivalent to temporally ordered serial schedules, where the temporal order is established by the transactions' start times. The algorithms provide this equivalence while supporting currency to the extent out-of-order commits and reads. With respect to the stated concern with optimistic approaches, two of the proposed algorithms are risk-free and return to read operations only committed data-item values. Risk with the third algorithm is greatly reduced by its conservative bias. All three algorithms avoid deadlock while providing risk-free or reduced-risk operation. The performance of the algorithms is determined analytically and with experimentation. Experiments are performed using functional database management system models that implement the proposed algorithms and the well-known Conservative Multiversion Timestamp Ordering algorithm. digital.library.unt.edu/ark:/67531/metadc2743/
Extensions to Jinni Mobile Agent Architecture
We extend the Jinni mobile agent architecture with a multicast network transport layer, an agent-to-agent delegation mechanism and a reflection based Prolog-to-Java interface. To ensure that our agent infrastructure runs efficiently, independently of router-level multicast support, we describe a blackboard based algorithm for locating a randomly roaming agent. As part of the agent-to-agent delegation mechanism, we describe an alternative to code-fetching mechanism for stronger mobility of mobile agents with less network overhead. In the context of direct and reflection based extension mechanisms for Jinni, we describe the design and the implementation of a reflection based Prolog-to-Java interface. The presence of subtyping and method overloading makes finding the most specific method corresponding to a Prolog call pattern fairly difficult. We describe a run-time algorithm which provides accurate handling of overloaded methods beyond Java's reflection package's limitations. digital.library.unt.edu/ark:/67531/metadc2773/
The Design Of A Benchmark For Geo-stream Management Systems
The recent growth in sensor technology allows easier information gathering in real-time as sensors have grown smaller, more accurate, and less expensive. The resulting data is often in a geo-stream format continuously changing input with a spatial extent. Researchers developing geo-streaming management systems (GSMS) require a benchmark system for evaluation, which is currently lacking. This thesis presents GSMark, a benchmark for evaluating GSMSs. GSMark provides a data generator that creates a combination of synthetic and real geo-streaming data, a workload simulator to present the data to the GSMS as a data stream, and a set of benchmark queries that evaluate typical GSMS functionality and query performance. In particular, GSMark generates both moving points and evolving spatial regions, two fundamental data types for a broad range of geo-stream applications, and the geo-streaming queries on this data. digital.library.unt.edu/ark:/67531/metadc103392/
Rapid Prototyping and Design of a Fast Random Number Generator
Information in the form of online multimedia, bank accounts, or password usage for diverse applications needs some form of security. the core feature of many security systems is the generation of true random or pseudorandom numbers. Hence reliable generators of such numbers are indispensable. the fundamental hurdle is that digital computers cannot generate truly random numbers because the states and transitions of digital systems are well understood and predictable. Nothing in a digital computer happens truly randomly. Digital computers are sequential machines that perform a current state and move to the next state in a deterministic fashion. to generate any secure hash or encrypted word a random number is needed. But since computers are not random, random sequences are commonly used. Random sequences are algorithms that generate a pattern of values that appear to be random but after some time start repeating. This thesis implements a digital random number generator using MATLAB, FGPA prototyping, and custom silicon design. This random number generator is able to use a truly random CMOS source to generate the random number. Statistical benchmarks are used to test the results and to show that the design works. Thus the proposed random number generator will be useful for online encryption and security. digital.library.unt.edu/ark:/67531/metadc115040/
Rapid Prototyping and Design of a Fast Random Number Generator
Information in the form of online multimedia, bank accounts, or password usage for diverse applications needs some form of security. the core feature of many security systems is the generation of true random or pseudorandom numbers. Hence reliable generators of such numbers are indispensable. the fundamental hurdle is that digital computers cannot generate truly random numbers because the states and transitions of digital systems are well understood and predictable. Nothing in a digital computer happens truly randomly. Digital computers are sequential machines that perform a current state and move to the next state in a deterministic fashion. to generate any secure hash or encrypted word a random number is needed. But since computers are not random, random sequences are commonly used. Random sequences are algorithms that generate a pattern of values that appear to be random but after some time start repeating. This thesis implements a digital random number generator using MATLAB, FGPA prototyping, and custom silicon design. This random number generator is able to use a truly random CMOS source to generate the random number. Statistical benchmarks are used to test the results and to show that the design works. Thus the proposed random number generator will be useful for online encryption and security. digital.library.unt.edu/ark:/67531/metadc115036/
3D Reconstruction Using Lidar and Visual Images
In this research, multi-perspective image registration using LiDAR and visual images was considered. 2D-3D image registration is a difficult task because it requires the extraction of different semantic features from each modality. This problem is solved in three parts. The first step involves detection and extraction of common features from each of the data sets. The second step consists of associating the common features between two different modalities. Traditional methods use lines or orthogonal corners as common features. The third step consists of building the projection matrix. Many existing methods use global positing system (GPS) or inertial navigation system (INS) for an initial estimate of the camera pose. However, the approach discussed herein does not use GPS, INS, or any such devices for initial estimate; hence the model can be used in places like the lunar surface or Mars where GPS or INS are not available. A variation of the method is also described, which does not require strong features from both images but rather uses intensity gradients in the image. This can be useful when one image does not have strong features (such as lines) or there are too many extraneous features. digital.library.unt.edu/ark:/67531/metadc177193/
FIRST PREV 1 2 3 NEXT LAST