Process mining: A recent framework for extracting a model from event logs

Business Process Management (BPM) is a well-known discipline, with roots in previous theories related with optimizing management and improving businesses results. One can trace BPM back to the beginning of this century, although it was in more recent years when it gained a special focus of attention. Usually, traditional BPM approaches start from top and analyse the organization according some known rules from its structure or from the type of business. Process Mining (PM) is a completely different approach, since it aims to extract knowledge from event logs, which are widely present in many of today’s organizations. PM uses specialized data-mining algorithms, trying to uncover patterns and trends in these logs, and it is an alternative approach where formal process specification is not easily obtainable or is not cost-effective. This paper makes a literature review of major works issued about this theme.(undefined

Inventário automático de sinais de trânsito: um sistema de mapeamento móvel

A inventariação e georeferenciação do mobiliário urbano é um processo fundamental para entidades responsáveis pela gestão destas infra-estruturas, fornecendo informação indispensável para o apoio à tomada de decisões. No entanto, o levantamento e processamento da informação necessária para esta inventariação são processos morosos devido à extensão da malha urbana. A utilização de Sistemas de Mapeamento Móveis (SMM) permite acelerar este levantamento, mas a informação deve ainda ser processada para localizar e identificar os objectos de interesse. Este artigo apresenta uma abordagem baseada em técnicas de Visão por Computador, que permite automatizar a localização e identificação de mobiliário urbano numa sequência de imagens obtida com um SMM. Esta abordagem restringe-se, nesta fase de estudo de viabilidade e prototipagem, à sinalização vertical de trânsito. A principal contribuição deste artigo consiste na introdução de um novo método de localização e identificação de sinais de trânsito em ambientes exteriores, baseado na segmentação pela cor, reconhecimento de formas usando assinaturas de contornos e identificação do sinal através de correlação monocromática. Os resultados obtidos demonstram uma taxa de sucesso global na ordem dos 75% e um aumento muito significativo de produtividade na fase de processamento de informação.Agência de Inovação (AdI

A comprehensive taxonomy for three-dimensional displays

Even though three-dimensional (3D) displays have been introduced in relatively recent times in the context of display technology, they have undergone a rapid evolution, to the point that a plethora of equipment able to reproduce dynamic three-dimensional scenes in real time is now becoming commonplace in the consumer market. This paper’s main contributions are (1) a clear definition of a 3D display, based on the visual depth cues supported, and (2) a hierarchical taxonomy of classes and subclasses of 3D displays, based on a set of properties that allows an unambiguous and systematic classification scheme for three-dimensional displays. Five main types of 3D displays are thus defined –two of those new–, aiming to provide a taxonomy that is largely backwards-compatible, but that also clarifies prior inconsistencies in the literature. This well-defined outline should also enable exploration of the 3D display space and devising of new 3D display systems.Fundação para a Ciência e Tecnologi

Guest editorial: high dynamic range imaging

High Dynamic Range (HDR) imagery is a step-change in imaging technology that is not limited to the 8-bits per pixel for each color channel that traditional or low-dynamic range digital images have been constrained to. These restrictions have meant that the current and relatively novel imaging technologies including stereoscopic, HD and ultraHD imaging do not provide an accurate representation of the lighting available in a real world environment. HDR technology has enabled the capture, storage, handling and display of content that supports real world luminance and facilitated the use of rendering methods in special effects, video games and advertising via novel rendering methods such as image-based lighting; it is also compatible with the other imaging methods and will certainly be a requirement of future high-fidelity imaging format specifications. However, HDR still has challenges to overcome before it can become a fully fledged commercially successful technology. This special issue goes someway in to rectify any limitations and also shines a light on future potential uses and directions of HDR

Instant global illumination on the GPU using OptiX

OptiX, a programmable ray tracing engine, has been recently made available by NVidia, relieving rendering researchers from the idiosyncrasies of efficient ray tracing programming and allowing them to concentrate on higher level algorithms, such as interactive global illumination. This paper evaluates the performance of the Instant Global Illumination algorithm on OptiX as well as the impact of three di fferent optimization techniques: imperfect visibility, downsampling and interleaved sampling. Results show that interactive frame rates are indeed achievable, although the combination of all optimization techniques leads to the appearance of artifacts that compromise image quality. Suggestions are presented on possible ways to overcome these limitations

Workload distribution for ray tracing in multi-core systems

One of the features that made interactive ray tracing possible over the last few years was the careful exploitation of the computational power and parallelism available on modern multicore processors. Multithreaded interactive ray tracing engines have to share the workload (rays to be processed) among rendering threads. This may be achieved by storing tasks on a shared FIFO-queue, accessed by all threads. Accessing this shared data structure requires a data access control mechanism, which ensures that the data structure is not corrupted. This access mechanism must incur minimal overheads such that performance is not penalized. This paper proposes a lock-free data access control mechanism to such queue, which avoids all locks by carefully reordering instructions. This technique is compared with a classical lock-based approach and with a conservative local technique, where each thread maintains its local queue of tasks and shares nothing with other threads. Although the local approach outperforms the other two due to very good load balancing conditions, we demonstrate that the lock-free approach outperforms the lock-based one for large processor counts. Efficient and reliable sharing of data structures within a shared memory system is becoming a very relevant problem with the advent of many core processors. Lock free approaches are a promising manner of achieving such goal

Foreword to the special section on the Spring Conference on Computer Graphics 2015 (SCCG'2015)

[Excerpt] It is our pleasure to present this special section of Computers & Graphics (C&G), featuring the selected best papers presented at the 31st Spring Conference on Computer Graphics 2015 (www. sccg.sk), which was held April 22–24, 2015 in Smolenice, Slovakia. The venue is probably the oldest regular annual meeting of computer graphics in Central Europe, covering all relevant innovative ideas in computer graphics, image processing and their applications. The philosophy of SCCG is to bring together top experts and young researchers in CG in order to support a good and sustained communication channel for East–West European exchange of prospective ideas. [...]info:eu-repo/semantics/publishedVersio

A real-time distributed software infrastructure for cooperating mobile autonomous robots

Cooperating mobile autonomous robots have been generating a growing interest in fields such as rescue, demining and security. These applications require a real time middleware and wireless communication protocol that can effecient and timely support the fusion of the distributed perception and the development of coordinated behaviors. This paper proposes an affordable middleware, based on low-cost and open-source COTS technologies, which relies on a real-time database partially replicated in all team members, containing both local and remote state variables, in a distributed shared memory style. This provides seamless access to the complete team state, with fast non-blocking local operations. The remote data is updated autonomously in the background by a WiFi-based wireless communication protocol, at an adequate refresh rate. The software infrastruture is complemented with a task manager that provides scheduling and synchronization services to the application processes on top of the Linux operating system. Such infrastructure has been successfully used for four years in one RoboCup middle-size soccer team, and it has proved to be dependable in the presence of uncontrolled spurious traffic in the communication channel, using an adaptive technique to synchronizating the robots in the team and reconfiguring the communications dynamically and automatically according, to the number of currently active team members

COGNITO - captura, reconhecimento e visualização de atividades manuais complexas

Neste artigo curto apresenta-se um sistema capaz de automaticamente capturar, reconhecer e visualizar atividades motoras humanas, em diferentes contextos, mas com aplicação prática, por exemplo, na implementação de manuais virtuais 3D ou em vídeo-jogos de nova geração, passando pelos simuladores de treino. Este trabalho tem vindo a ser desenvolvido em consórcio internacional, no contexto de um projeto apoiado pela comissão europeia (COGNITO), e tem-se centrado na captura, análise, armazenamento e visualização 3D, com recurso a tecnologias de realidade virtual e aumentada, de tarefas manuais complexas, executadas em ambiente industrial. O sistema é composto por quatro módulos principais: uma rede de sensores colocados no corpo, uma unidade de captura dos movimentos e ferramentas utilizadas, uma componente de aprendizagem não supervisionada e uma componente gráfica capaz de fazer a apresentação de informação ao utilizador através de um módulo de realidade aumentada (RA). Este artigo apresenta o sistema global e a sua arquitetura, referindo com mais detalhe os desenvolvimentos efetuados para a componente gráfica