Feng Zezheng, Li Haotian, Zeng Wei, Yang Shuang-Hua, Qu Huamin
IEEE Trans Vis Comput Graph. 2021 Feb;27(2):828-838. doi: 10.1109/TVCG.2020.3030469. Epub 2021 Jan 28.
Density map is an effective visualization technique for depicting the scalar field distribution in 2D space. Conventional methods for constructing density maps are mainly based on Euclidean distance, limiting their applicability in urban analysis that shall consider road network and urban traffic. In this work, we propose a new method named Topology Density Map, targeting for accurate and intuitive density maps in the context of urban environment. Based on the various constraints of road connections and traffic conditions, the method first constructs a directed acyclic graph (DAG) that propagates nonlinear scalar fields along 1D road networks. Next, the method extends the scalar fields to a 2D space by identifying key intersecting points in the DAG and calculating the scalar fields for every point, yielding a weighted Voronoi diagram like effect of space division. Two case studies demonstrate that the Topology Density Map supplies accurate information to users and provides an intuitive visualization for decision making. An interview with domain experts demonstrates the feasibility, usability, and effectiveness of our method.
密度图是一种用于描绘二维空间中标量场分布的有效可视化技术。传统的构建密度图的方法主要基于欧几里得距离，这限制了它们在需要考虑道路网络和城市交通的城市分析中的适用性。在这项工作中，我们提出了一种名为拓扑密度图的新方法，旨在在城市环境中生成准确且直观的密度图。基于道路连接和交通状况的各种约束，该方法首先构建一个有向无环图（DAG），它沿着一维道路网络传播非线性标量场。接下来，该方法通过识别DAG中的关键交点并计算每个点的标量场，将标量场扩展到二维空间，产生类似加权Voronoi图的空间划分效果。两个案例研究表明，拓扑密度图为用户提供了准确的信息，并为决策提供了直观的可视化。对领域专家的访谈证明了我们方法的可行性、可用性和有效性。
