Map matching is the process of assigning observed geographic positions of vehicles and their trajectories to the actual road links in a road network. In this paper, we present Visual Interactive Map Matching, a visual analytics approach to fine-tune the data preprocessing and matching process. It is based on ST-matching, a state-of-the-art and easy-to-understand map matching algorithm. Parameters of the preprocessing step and algorithm can be optimized with immediate visual feedback. Visualizations show current matching issues and performance metrics on a map and in diagrams. Manual and computer-supported editing of the road network model leads to a refined alignment of trajectories and roads. We demonstrate our approach with large-scale taxi trajectory data. We show that optimizing the matching on a subsample results in considerably improved matching quality, also when later scaled to the full dataset. An optimized matching ensures data faithfulness and prevents misinterpretation when the matched data might be investigated in follow-up analysis.

As software projects continue to grow in scale, being able to maximize the work that developers can carry out in parallel as a set of concurrent development tasks, without incurring excessive coordination overhead, becomes increasingly important. Prevailing design models, however, are not explicitly conceived to suggest how development tasks on the software modules they describe can be effectively parallelized. In this paper, we present a design rule hierarchy based on the assumption relations among design decisions. Software modules located within the same layer of the hierarchy suggest independent, hence parallelizable, tasks. Dependencies between layers or within a module suggest the need for coordination during concurrent work. We evaluate our approach by investigating the source code and mailing list of Apache Ant. We observe that technical communication between developers working on different modules within the same hierarchy layer, as predicted, is significantly less than communication between developers working across layers.