The previous chapter introduces the basic notions of data visualization. Further, it presents several state-of-the-art visualization methods and tools, which have been recently proposed from the Data Management and Information Visualization communities, for handling Big datasets. This chapters focus on Linked Data, presenting tools, features, techniques, and tasks that have been developed for LD visualization. It classifies the works, into categories and subcategories, based on several criteria, such as data and visualization types, functionality and working scenarios.
Initially, a chronological overview of the tools per category is presented. The analysis of the timeline allows to capture interesting insights regarding the evolution of the tools through time for each category. Then, an extensive review on LD exploration and visualization tools is provided. Particularly, around 120 visualization tools from several categories are presented. For each of these tools, we discuss several issues related to the its functionality and the characteristics. For example, supported data and visualization types; basic features and advanced functionalities; tasks which tools focuses on; technical information, etc. Note that, some of the tools presented here, are also evaluated in Chapter 5, where more details regarding their functionality and characteristic are presented.
In what follows, the tools are classified into five basic categories: (1) Browsers and exploratory tools (Section 3.2); (2) Tools using multiple visualization types (Section 3.3); (3) Graph-based visualization tools (Section 3.4); (4) Domain & Vocabulary-specific, and Device-oriented visualization tools (Section 3.5); and (5) Ontology visualization tools (Section 3.6).