We propose incremental logarithmic time-series technique as a way to deal with time-based representations of large and dynamic event data sets in limited space. Modern data visualization problems in the domains of news analysis, network security and financial applications, require visual analysis of incremental data, which poses specific challenges that are normally not solved by static visualizations. The incremental nature of the data implies that visualizations have to necessarily change their content and still provide comprehensible representations. In particular, in this paper we deal with the need to keep an eye on recent events together with providing a context on the past and to make relevant patterns accessible at any scale. Our technique adapts to the incoming data by taking care of the rate at which data items occur and by using a decay function to let the items fade away according to their relevance. Since access to details is also important, we also provide a novel distortion magnifying lens technique which takes into account the distortions introduced by the logarithmic time scale to augment readability in selected areas of interest. We demonstrate the validity of our techniques by applying them on incremental data coming from online news streams in different time frames.

Photo-sharing websites such as Flickr and Panoramio contain millions of geotagged images contributed by people from all over the world. Characteristics of these data pose new challenges in the domain of spatio-temporal analysis. In this paper, we define several different tasks related to analysis of attractive places, points of interest and comparison of behavioral patterns of different user communities on geotagged photo data. We perform analysis and comparison of temporal events, rankings of sightseeing places in a city, and study mobility of people using geotagged photos. We take a systematic approach to accomplish these tasks by applying scalable computational techniques, using statistical and data mining algorithms, combined with interactive geo-visualization. We provide exploratory visual analysis environment, which allows the analyst to detect spatial and temporal patterns and extract additional knowledge from large geotagged photo collections. We demonstrate our approach by applying the methods to several regions in the world.

The analysis of large quantities of news is an emerging area in the field of data analysis and visualization. International agencies collect thousands of news every day from a large number of sources and making sense of them is becoming increasingly complex due to the rate of the incoming news, as well as the inherent complexity of analyzing large quantities of evolving text corpora. Current visual techniques that deal with temporal evolution of such complex datasets, together with research efforts in related domains like text mining and topic detection and tracking, represent early attempts to understand, gain insight and make sense of these data. Despite these initial propositions, there is still a lack of techniques dealing directly with the problem of visualizing news streams in a "on-line" fashion, that is, in a way that the evolution of news can be monitored in real-time by the operator. In this paper we propose a purely visual technique that permits to see the evolution of news in real-time. The technique permits to show the stream of news as they enter into the system as well as a series of important threads which are computed on the fly. By merging single articles into threads, the technique permits to offload the visualization and retain only the most relevant information. The proposed technique is applied to the visualization of news streams generated by a news aggregation system that monitors over 4000 sites from 1600 key news portals worldwide and retrieves over 80000 reports per day in 43 languages.

While Internet has enabled us to access a vast amount of online news articles originating from thousands of different sources, the human capability to read all these articles has stayed rather constant. Usually, the publishing industry takes over the role of filtering this enormous amount of information and presenting it in an appropriate way to the group of their subscribers. In this paper, the semantic analysis of such news streams is discussed by introducing a system that streams online news collected by the Europe Media Monitor to our proposed semantic news analysis system. Thereby, we describe in detail the emerging challenges and the corresponding engineering solutions to process incoming articles close to real-time. To demonstrate the use of our system, the case studies show a) temporal analysis of entities, such as institutions or persons, and b) their co-occurence in news articles.

Abstract-Visualizing data streams poses numerous challenges in the data, image and user space. In the era of big data, we need incremental visualization methods that will allow the analysts to explore data faster and help them make important decisions on time. In this paper, we have reviewed several wellknown information visualization methods that are commonly used to visualize static datasets and analyzed their degrees of freedom. By observing which independent visual variables can change in each method, we described how these changes are related to the attribute and structure changes that can occur in the data stream. Most of the changes in the data stream lead to potential loss of temporal and relational context between the new data and the past data. We present potential directions for measuring the amount of change and loss of context by reviewing related work and identify open issues for future work in this domain.

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Online news sources produce thousands of news articles every day, reporting on local and global real-world events. New information quickly replaces the old, making it difficult for readers to put current events in the context of the past. The stories about these events have complex relationships and characteristics that are difficult to model: they can be weakly or strongly related or they can merge or split over time. In this article, we present a visual analytics system for temporal analysis of news stories in dynamic information streams, which combines interactive visualization and text mining techniques to facilitate the analysis of similar topics that split and merge over time. Text clustering algorithms extract stories from online news streams in consecutive time windows and identify similar stories from the past. The stories are displayed in a visualization, which (1) sorts the stories by minimizing clutter and overlap from edge crossings, (2) shows their temporal characteristics in different time frames with different levels of detail, and (3) allows incremental updates of the display without recalculating the past data. Stories can be interactively filtered by their duration and connectivity in order to be explored in full detail. To demonstrate the system's capabilities for detailed dynamic text stream exploration, we present a use case with real news data about the Arabic Uprising in 2011.

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