## 4 Interactive Visualization System
### Visualization Design  
Control Panel: This panel provides functions related to network dataset selection, visual appearance adjustments, network layout algorithm selection, and layout preference setting. The network dataset selection function enables switching or uploading network datasets, as the input for the entire system. Visual appearance control allows users to adjust visual properties of nodes and edges within the main view, including node radius size, node colors, edge width, and edge colors. Network layout algorithm selection enables switching among different layout algorithms, providing the system with the flexibility to support various algorithms. This offers users more choices and enhances system compatibility  
Figure 8: The user interface of dynamic network visualization system, which consists of (**A**) the control panel, (**B**) the main view, (**C**) the snapshots view, (**D**) the temporal views, and (**E**) the feature statistics view. Figure 7: The pipeline of our dynamic network visualization system. with a wider range of data types. The SIPA algorithm is selected by default. If the layout result is not satisfactory, users can switch to FR, Incremental or Aging algorithms. The Layout preference panel allow users to set their preference on layout stability and quality. The slider is in the middle by default, user can move it based on their preference and the network layout results. Main View: This view present the layout results of the network, which convey the topological structural information of the network. When there are significant structural changes in the network, such as the simultaneous addition or removal of multiple nodes and edges, the positions of network nodes undergo substantial alterations, making it difficult for users to comprehend how the network transitions from one structure to another. To address this, we employ a segmented animation approach inspired by the design of GraphDiaries [29]. The animation is implemented with the transition module of D3 [43] visualization library, The duration of a transition is set to 750 milliseconds for now, and future study needs to be performed for choosing a optimal duration value. The network's structural changes are divided into three stages: node deletion, node addition, and node movement, and highlighting is applied before structure deletion and after structure addition to emphasize the changes in network structure (see Figure 9). Additionally, during the node movement stage, to facilitate user observation and tracking of node position changes, we employ node movement interpolation and retain movement traces to better present the process of node position changes. Network snapshot views: Utilizing animation to represent dynamic networks aids users in observing and comprehending changes in network structure. However, due to the inherent volatility of dynamic network structures and limitations in users' memory capacity, it becomes challenging for users to simultaneously understand the current network structural changes while retaining information about the network's former structures. This impedes users' ability to compare structural differences between different time steps effectively and hinders their ability to gain an overview of the network's structural characteristics at various moments, as well as to identify patterns in network evolution. To address this issue, a Network Structural Snapshot module has been designed to store structural information from previous network states. Network feature Statistics views: The networks itself possesses many characteristic features, such as the number of network nodes, edge count, degree information of nodes in the network, and the structural composition of network communities. While these information are valuable for understanding networks, expressing them through the layout diagram of the network is challenging.