TraVis - A visualization framework for mobile transect data sets in an urban microclimate context

In urban microclimate research, mobile transects are utilized to observe the relationship between atmospheric variables and the urban environment. However, the data sets resulting from mobile measurements are complex: They are spatially dependent, multivariate, and often-times multitemporal. At the same time, the spatial context of each observation - its field of view and area represented - is physically complex and dynamic. These properties make analysis and visualization challenging. We present a prototype visualization framework that assists researchers in the analysis of mobile transect measurements. The system enables users to visualize and explore observations as walls that delineate the transect route on a map. The observed attributes are stacked upon each other within these walls as ribbons to facilitate the qualitative analysis of spatial variability and multivariate correlations. The relationship between observations and spatial context can interactively be explored by moving a slider along the transect route. For each observation on the track, the spatially contextual source area is displayed and linked to a view of the fraction of land cover classes contained within the source area. These qualitative analysis capabilities are complemented by an interactive clustering interface, which allows for the classification of transect segments according to a coherent pattern of multivariate relationships between a user-defined set of observations. The framework was developed by a team comprising both visualization and urban microclimate researchers, and a case study shows its utility for this specialized application.