## 2 Related Work  
### Interactions in Adjacency Matrix  
Three main interaction techniques are used to explore the adjacency matrix [12]: Focus+Context, Overview+Detail, and PankZoom. Focus+Context technology distorts the information space; Overview+Details requires additional view assistance to display information and user effort to correlate the two; and PankZoom results in higher working memory because the user can see only one view at a time.  
Focus+Context comes in two major forms: lens and fold. The lens usually emphasizes the contents of an area using magnification, such as suppressing scattered information, showing details, and changing mappings. PaperLens [13] uses square hardware as a lens to transform the view of the covered area, and the size of the lens coverage area is relatively fixed. RMC [6] solves this problem by scaling the lens view transformation area. BodyLens [14], SpiderEye [15], and ShadowTouch [16] use lenses with different shapes (round, rectangular, humanoid outline) to change the view mapping to show details, and can adjust the size of the covered area. However, the above directly overwrites the original view due to insufficient display space, resulting in information loss. Melang [17] is a 3D distortion technology that folds the uninterested part to the rear to reduce the display area. Similarly, SpaceFold [18] and Multi-touch document folding [19; 20] support multiple focal points to be displayed at the same time. Still, the focus shape is relatively fixed, the number of focal points is limited, the deformation is more serious, and more information is lost.  
Overview+Details comes in three major forms: mini-maps, different views from different perspectives, and view slices. A mini-map is a small map of the whole world, providing an overview of the user and the relationship between the details and the entire world. Different views from different perspectives are used to display details of new areas  
Figure 1: Multivariate Fence—A focus view model for adjacency matrix showing node attributes.  
through other views. MARVIS [21] displays node attributes in the figure as bar charts beside the Overview area. View slicing extracts part of the global view as details and zooms in to display. Visualizing Dynamic Networks [22] uses this method to show details of the matrix cube. This interaction technique can take up limited view space or require the new view presentation space to be expanded.  
Pan&Zoom technology includes geometric and semantic zooming. The former specifies the scale of the enlarged spatial scales, while the latter changes the level of detail by changing the visual code. [PERSON] and [PERSON] summarized smooth and efficient geometric zooming and panning techniques and presented a model to calculate a solution for optimal-view animations [12; 23]. ZAME [5] and TimeMatrix [24] are content-aware technologies that rely on semantic zooming to display different encoding details based on the scale level. Semantic scaling is also included in RMC [6], where four levels of details (LOD) are designed based on the scale level. Pan&Zoom technology provides users with more multivariate information through zoom operation.  
This work mainly aims to improve the problems of space limitation and occlusion, display multiple attributes of nodes without blocking the region of interest (ROI), and support more free zooming.