Busca de padroes em subdivisoes planares

Orientador: André Luiz Pires GuedesDissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Ciencias Exatas, Programa de Pós-Graduaçao em Informática. Defesa: Curitiba, 2004Inclui bibliografiaResumo: O sub-isomorfismo de grafos é uma abordagem muito utilizada para solucionar problemas de busca de padrões, mas este e um problema NP-completo. Desta forma, deve-se investir em pesquisa para encontrar soluções aproximadas, ou que funcionem em casos especiais do problema. Subdivisões planares podem ser consideradas um caso especial de grafos, pois, além dos vértices e arestas, existe uma topologia mais r³gida quanto µa ordem das arestas, surgindo o conceito de face. Este trabalho apresenta um algoritmo linear para busca de padrões em subdivisões planares. Os padrões a serem buscados também são considerados subdivisões e, portanto, este e um problema de sub-isomorfismo. O algoritmo apresentado baseia-se em uma representação h³brida entre o dual e o grafo de regiões adjacentes (RAG) para representar os padrões, de forma a não ter qualquer custo adicional de armazenamento. Então, os padrões são procurados na subdivisão de busca, utilizando um algoritmo de crescimento de regiões. Este trabalho também realiza um estudo comparativo das estruturas de dados mais utilizadas para armazenamento de subdivisões planares.Abstract: Graph sub-isomorphism is a very used approach to solving pattern search problems, but this is a NPcomplete problem. This way, it is necessary to invest in research of approximate solutions, or in special cases of the problem. Planar subdivisions can be considered as a special case of graphs, because, in addition to nodes and edges, there is a more rigid topology in relation to the order of the edges, arising to the concept of face. This work presents a linear algorithm for pattern search in planar subdivisions. The patterns to be searched are also considered subdivisions, and therefore it is a sub-isomorphism problem. The presented algorithm is based on a hybrid approach between the dual and the region adjacency graph (RAG) to represent the patterns, saving additional storage costs. Thus, the patterns are looked over the search subdivision, using an algorithm of region growing. This work also performs a comparative study of the data structures commonly used for storage of planar subdivisions

The design and analysis of boundary data structures

The thesis is concerned with the efficient interrogation of CAD data. CAD data finds use in diverse range of applications which necessitates extension and integration of the CAD data base. By an exhaustive categorization of such application requirements and analysis of various CAD techniques, it is shown that boundary data structures are the most suitable in CAD, CAM and advanced robotic applications. Several boundary data structures have been proposed since the classic Winged edge data structure, these aimed at reducing the storage requirement and increasing information retrieval speeds. In this thesis methodologies are developed which enable us to discover compact and fast access time schemes and analyze and fine tune for individual applications. We demonstrate how the application of the optimality concepts can lead us to the discovery of more efficient data structures than popular data structures. All the boundary data structures proposed to date have been based on the underlying assumption that all the data resides in main memory. We show that in an integrated CAD environment (characterized by virtual a memory environment or a data base environment), these data structures are inefficient in both storage and time. We propose a new data structure shaped like A which is the most compact as well as more efficient in access time, under certain conditions of real memory and virtual memory. Experiments reveal a paradoxical phenomenon: access time increases with storage, violating the classic law of storage vs. time. Recently non-manifold boundary geometric modeling has become popular to meet the growing needs such as uniform treatment of wire frame, surface and solid modeling and design by features. We introduce a uniform terminology and notation to distinguish and critically analyze several non-manifold boundary data structures. It is hoped to fulfill the need for a ready reference for the design of efficient boundary data structures. The other aspects dealt with are the validity and conversion of Boundary data structures. To verify the concepts developed, in practice, a whole suite of fast algorithms have been implemented for model manipulation, visualization and data conversion

Sensing and real-time expert system for a masonry building robot

The construction industry is striving to eliminate dangerous and repetitive work, as well as increase quality and productivity in the various tasks. For this reason, there is growing interest in the use of automation and robotics. However, the requirements of robots for construction are different from those of industrial robots, due to the characteristics of the construction tasks and the relatively unstructured working environment. The main objective of this research is to investigate the enabling technology for a masonry tasking robot, utilising an experimental robot cell. To truly automate the masonry construction task, there is need to utilise the advancement in robotic technology, especially to deal with the unstructured environment. This view is in-line with this research, which attempts to solve part of the complex problems of automating the building task, by using forms of sensing and intelligence. Concentration on this is the main distinguishing difference between this work and the few other attempts at physical realisation and experimentation in masonry automation. In terms of research and development of masonry tasking machines and robots, there is much activity on an international scale. Concerning the provisions for machine intelligence in this, it appears that the work reported has the most advanced provisions for computer intelligence. This work is of general relevance to construction robots because imprecision, dynamic performance, unplanned events and cell component relocation are considered. The experimental robot cell, built at City University, is used in the research. Standard construction materials have been adopted with imprecise dimensions. Using a CAD/CAM facility, building project designs are translated into robot’s ‘theoretical task’. However, because the masonry material is unpredictable, this can not be directly implemented without real-time adjustments derived from sensing. Not withstanding, advantage is taken of pre-processing, with real-time accommodation of discrepancies, obstacle avoidance and un-planned events. In this, the robot cell performs intelligent processing using rule-based expert systems to carry out the masonry building tasks. Such a process contributes to the fundamental basis for the automation of all stages of building, from architectural planning through to execution of the construction work. A further complication is that the form of a move influences the dynamic response of the robot structure. Therefore, the structural dynamics response of the robot is taken into account in order to optimise performance. Rule based expert systems are investigated to enable a goal driven, intelligent planning approach to be implemented, that can provide an effective dynamic plan for the building task, as well as real-time adjustments to the automatically generated ‘theoretical task’. XXVI