21 documents found, page 1 of 3
A model-driven approach to enhance data visualization through domain knowledge ...
Almeida, Andreia; Alves, Alberto; Santos, Maribel Yasmina; León, Ana; Pires, João MouraBig Data is challenging analytical contexts, namely when aligning data and analytical requirements. While the capacity to collect and store new data is expanding rapidly, the pace at which it can be analyzed is developing more slowly. Defining these analytical requirements and selecting the most appropriate visualizations often depends on an in-depth understanding of what users need from the data. To address th...
When granules are not enough in a Theory of Granularities
Silva, Ricardo Almeida; Pires, João Moura; Santos, Maribel YasminaSeveral approaches have been proposed to model spatiotemporal phenome- na at multiple LoDs, in particularly, under the granular computing research area, where a granularities-based model was proposed. Such model stands out from the related literature, but has two major limitations. On one hand, it has difficulties for describing regions, intervals of time, among others complex descriptions, and on the other han...
Dealing with repeated objects in SNNagg
Galvão, João Rui Magalhães Velho da Cunha; Santos, Maribel Yasmina; Pires, João Moura; Costa, CarlosDue to the constant technological advances and massive use of electronic devices, the amount of data generated has increased at a very high rate, leading to the urgent need to process larger amounts of data in less time. In order to be able to handle these large amounts of data, several techniques and algorithms have been developed in the area of knowledge discovery in databases, which process consists of sever...
Enhancing exploratory analysis by summarizing spatiotemporal events across mult...
Silva, Ricardo Almeida; Pires, João Moura; Santos, Maribel Yasmina; Datia, NunoThere are many spatiotemporal events with high levels of detail (LoDs) being collected in many phenomena. The LoD of analysis plays a crucial role in the user’s perception of phenomena. From one LoD to another, some patterns can be easily perceived or different patterns may be detected. Standard practices work on a single LoD driven by the user in spite of the fact that there is no exclusive LoD to study a phen...
Geo-spatial analytics using the dynamic ST-SNN Approach
Santos, Maribel Yasmina; Pires, João Moura; Moreira, Guilherme; Oliveira, Ricardo; Mendes, Fernando; Costa, CarlosSpatio-temporal clustering is a subfield of data mining that is increasingly gaining more scientific attention due to the advances of location-based devices that register position, time and, in some cases, other attributes. Spatio-temporal clustering intends to group objects based in their spatial and temporal similarity helping to discover interesting spatio-temporal patterns and correlations in large data set...
Understanding the SNN input parameters and how they affect the clustering results
Moreira, Guilherme; Santos, Maribel Yasmina; Pires, João Moura; Galvão, João Rui Magalhães Velho da CunhaHuge amounts of data are available for analysis in nowadays organizations, which are facing several challenges when trying to analyze the generated data with the aim of extracting useful information. This analytical capability needs to be enhanced with tools capable of dealing with big data sets without making the analytical process an arduous task. Clustering is usually used in the data analysis process, as th...
Aggregating spatio-temporal phenomena at multiple levels of detail
Silva, Ricardo; Pires, João Moura; Santos, Maribel Yasmina; Leal, RuiSpatio-temporal data are collected at high levels of detail (LoDs). Both spatial and temporal characteristics of data can be expressed at different LoDs. Depending on the phenomenon and the analytical goal, different LoDs can be suitable for a user’s analysis since different LoDs may provide different percep- tions of a phenomenon. It is crucial to model spatio-temporal phenomena having in mind that different L...
Detection of road accident accumulation zones with a visual analytics approach
Ramos, Luís F.; Silva, Luís; Santos, Maribel Yasmina; Pires, João MouraNowadays, road accidents are a major public health problem, which increase is forecasted if road safety is not treated properly, dying about 1.2 million people every year around the globe. In 2012, Portugal recorded 573 fatalities in road accidents, on site, revealing the largest decreasing of the European Union for 2011, along with Denmark. Beyond the impact caused by fatalities, it was calculated that the eco...
A granularity theory for modelling spatio-temporal phenomena at multiple levels...
Silva, Ricardo; Pires, João Moura; Santos, Maribel YasminaReasoning about spatio-temporal phenomena requires the adoption of common granularities that facilitate and enhance the comprehension of a particular phenomenon. In our day-to-day activities, spatial granules like state, province or country, and temporal granules like day, month or year, are used to index facts and to allow reasoning adopting the level of detail considered appropriate in a particular analytical...
kd-SNN : a metric data structure seconding the clustering of spatial data
Faustino, Bruno Filipe; Pires, João Moura; Santos, Maribel Yasmina; Moreira, GuilhermeLarge amounts of spatio-temporal data are continuously col- lected through the use of location devices or sensor technologies. One of the techniques usually used to obtain a first insight on data is clus- tering. The Shared Nearest Neighbour (SNN) is a clustering algorithm that finds clusters with different densities, shapes and sizes, and also identifies noise in data, making it a good candidate to deal with s...