Maps are traditional means of presentation and tools for analysis of spatial information. The power of maps can be also put into service in analysis of spatio-temporal data, i.e. data about phenomena that change with time. Exploration of such data requires highly interactive and dynamic maps. Using geospatial open source software, various techniques for visualizing spatial temporal network change data and combinations of spatial temporal network, point and area data are evaluated. Linear referencing represents locations along routes, linear features with an established measurement system, using relative positions. It allows locating events along routes without segmenting it, and has been applied to manage linear features in transportation, utilities, along trail networks and stream networks. Linear referencing for events occurring along a network through time are visualized using both animations and interactive time line visualizations. Sliders are used to give the user manual control to step through the data, allowing them to explore the data presented in each time step. Categorized point events (i.e. traffic accident types, flood locations, etc.) appear at muItiple locations along the network. Color and size of symbols are used to denote these dynamic point event attribute changes and location changes. In addition, line segments are mapped using size and color to identify the changes occurring over time. Some of the combinations of changes evaluated include: attribute change (i.e. traffic accident type), spatial attribute change (i.e. flood boundaries), moving objects (i.e. traffic accidents), rate of change (i.e. fish survival by stream segment) and spatio-temporal aggregation (i.e. multiple fish releases by watershed). Some linear visualization techniques evaluated include: run maps and map and line chart visualization techniques similar to the famous Napoleon's retreat Minard visualization. |