Space-Time Cube for Visual Queries over Metadata of Heterogeneous Geodata

Nowadays, huge amounts of geodata are increasingly made accessible on geodata portals. Typically, these data portals provide extensive metadata with various attributes, such as topic, size, and quality, that describe basic information about the datasets. However, at present, there is still insufficient work using visual interfaces to support the intuitive understanding of the overall distribution of metadata and make efficient decisions on which datasets they want. In this study, we designed a visual interface to display the metadata based on a space-time cube (STC) visualization, through which users could gain not only an overview of the metadata, but also detailed information about individual metadata attributes. We evaluated the design with 32 participants who were asked to perform five predefined benchmark tasks. The evaluation results show that most users can successfully finish tasks in finding specific datasets. This demonstrates that the space-time cube can provide a good overview and is visually attractive to potential users of the data portal. Nevertheless, the design has some limitations, e.g., the selection of color scheme and 3D symbol shape, which we need to improve in our future work. Besides, STC is rather new to most participants, and some of them were not used to this type of visualization. We believe that the space-time cube could be deployed as a supplementary method for displaying metadata in open data portals if sufficient user guidance is provided.