In the recent announcements of VIS2021 accepted papers, HKUST VisLab has 7 full papers and 1 art paper accepted. They have covered different directions of data visualization research, including AI4VIS, Human-Centered AI, Situated Visualization, Computational Social Science, and Data Storytelling. The institutions of collaborators include MIT, CMU, University of California San Diego, Singapore Management University, Michigan State University, Adobe Research, Zhejiang University, Tongji University, and MSRA.
AI4VIS: Visualization Recommendation based on Machine Learning
Visualization recommendation or automatic visualization generation can significantly lower the barriers for general users to rapidly create effective data visualizations, especially for those users without a background in data visualizations. However, existing rule-based approaches require tedious manual specifications of visualization rules by visualization experts. Recently, machine-learning-based visualization recommendation has become a research surge.
KG4Vis: A Knowledge Graph-Based Approach for Visualization Recommendation
Haotian Li, Yong Wang, Songheng Zhang, Yangqiu Song, Huamin Qu
Project Page: kg4vis.github.io
Visualization recommendation or automatic visualization generation can significantly lower the barriers for general users to rapidly create effective data visualizations, especially for those users without a background in data visualizations. However, existing rule-based approaches require tedious manual specifications of visualization rules by visualization experts. Other machine learning-based approaches often work like black-box and are difficult to understand why a specific visualization is recommended, limiting the wider adoption of these approaches. This paper fills the gap by presenting KG4Vis, a knowledge graph (KG)-based approach for visualization recommendation. It does not require manual specifications of visualization rules and can also guarantee good explainability. Specifically, we propose a framework for building knowledge graphs, consisting of three types of entities (i.e., data features, data columns, and visualization design choices) and the relations between them, to model the mapping rules between data and effective visualizations. A TransE-based embedding technique is employed to learn the embeddings of both entities and relations of the knowledge graph from existing dataset-visualization pairs. Such embeddings intrinsically model the desirable visualization rules. Then, given a new dataset, effective visualizations can be inferred from the knowledge graph with semantically meaningful rules. We conducted extensive evaluations to assess the proposed approach, including quantitative comparisons, case studies, and expert interviews. The results demonstrate the effectiveness of our approach.

MultiVision: Designing Analytical Dashboards with Deep Learning Based Recommendation
Aoyu Wu, Yun Wang, Mengyu Zhou, Xinyi He, Haidong Zhang, Huamin Qu and Dongmei Zhang
Project Page: github.com/Franches/MultiVision
We contribute a deep-learning-based method that assists in designing analytical dashboards for analyzing a data table. Given a data table, data workers usually need to experience a tedious and time-consuming process to select meaningful combinations of data columns for creating charts. This process is further complicated by the needs of creating dashboards composed of multiple views that unveil different perspectives of data. Existing automated approaches for recommending multiple-view visualizations mainly build on manually crafted design rules, producing sub-optimal or irrelevant suggestions. To address this gap, we present a deep learning approach for selecting data columns and recommending multiple charts. More importantly, we integrate the deep learning models into a mixed-initiative system. Our model could make recommendations given optional user-input selections of data columns. The model, in turn, learns from provenance data of authoring logs in an offline manner. We compare our deep learning model with existing methods for visualization recommendation and conduct a user study to evaluate the usefulness of the system.

Human-Centered AI: Model Interpretation and Visualization
Human-centered AI aims to apply techniques to solve the explainable, fairness, and reliabile issues in the AI systems. Visualization techniques have constructed a new bridge between the human and AI by using its effective information delivery capability.
M2Lens: Visualizing and Explaining Multimodal Models for Sentiment Analysis
Xingbo Wang, Jianben He, Zhihua Jin, Muqiao Yang, Yong Wang and Huamin Qu
Multimodal sentiment analysis aims to recognize people’s attitudes from multiple communication channels such as verbal content (i.e., text), voice, and facial expressions. It has become a vibrant and important research topic in natural language processing. Much research focuses on modeling the complex intra- and inter-modal interactions between different communication channels. However, current multimodal models with strong performance are often deep-learning-based techniques and work like black boxes. It is not clear how models utilize multimodal information for sentiment predictions. Despite recent advances in techniques for enhancing the explainability of machine learning models, they often target unimodal scenarios (e.g., images, sentences), and little research has been done on explaining multimodal models. In this paper, we present an interactive visual analytics system, M2Lens, to visualize and explain multimodal models for sentiment analysis. M2Lens provides explanations on intra- and inter-modal interactions at the global, subset, and local levels. Specifically, it summarizes the influence of three typical interaction types (i.e., dominance, complement, and conflict) on the model predictions. Moreover, M2Lens identifies frequent and influential multimodal features and supports the multi-faceted exploration of model behaviors from language, acoustic, and visual modalities. Through two case studies and expert interviews, we demonstrate our system can help users gain deep insights into the multimodal models for sentiment analysis.

VBridge: Connecting the Dots Between Features, Explanations, and Data for Healthcare Models
Furui Cheng, Dongyu Liu, Fan Du, Yanna Lin, Alexandra Zytek, Haomin Li, Huamin Qu, Kalyan Veeramachaneni
Machine learning (ML) is increasingly applied to Electronic Health Records (EHRs) to solve clinical prediction tasks. Although many ML models perform promisingly, issues with model transparency and interpretability limit their adoption in clinical practice. Directly using existing explainable ML techniques in clinical settings can be challenging. Through literature surveys and collaborations with six clinicians with an average of 17 years of clinical experience, we identified three key challenges, including clinicians’ unfamiliarity with ML features, lack of contextual information, and the need for cohort-level evidence. Following an iterative design process, we further designed and developed VBridge, a visual analytics tool that seamlessly incorporates ML explanations into clinicians’ decision-making workflow. The system includes a novel hierarchical display of contribution-based feature explanations and enriched interactions that connect the dots between ML features, explanations, and data. We demonstrated the effectiveness of VBridge through two case studies and expert interviews with four clinicians, showing that visually associating model explanations with patients’ situational records can help clinicians better interpret and use model predictions when making clinician decisions. We further derived a list of design implications for developing future explainable ML tools to support clinical decision-making.

Situated Visualization: Visualization in Sports Video Analysis
With the development of sensors, 5G, IOT, more and more data about the real world data are collected. The Augmented Reality (AR) devices enable people to combine these data to explore visualization in a situated manner. Siutated visualization aims to present the data in front of the data context, which help people better understand the data and enhance the experience to the real world.
Augmenting Sports Videos with VisCommentator
Zhutian Chen, Shuainan Ye, Xiangtong Chu, Haijun Xia, Hui Zhang, Huamin Qu, and Yingcai Wu
Project Page: viscommentator.github.io
Visualizing data in sports videos is gaining traction in sports analytics, given its ability to communicate insights and explicate player strategies engagingly. However, augmenting sports videos with such data visualizations is challenging, especially for sports analysts, as it requires considerable expertise in video editing. To ease the creation process, we present a design space that characterizes augmented sports videos at an element-level (what the constituents are) and clip-level (how those constituents are organized). We do so by systematically reviewing 233 examples of augmented sports videos collected from TV channels, teams, and leagues. The design space guides selection of data insights and visualizations for various purposes. Informed by the design space and close collaboration with domain experts, we design VisCommentator, a fast prototyping tool, to eases the creation of augmented table tennis videos by leveraging machine learning-based data extractors and design space-based visualization recommendations. With VisCommentator, sports analysts can create an augmented video by selecting the data to visualize instead of manually drawing the graphical marks. Our system can be generalized to other racket sports (e.g., tennis, badminton) once the underlying datasets and models are available. A user study with seven domain experts shows high satisfaction with our system, confirms that the participants can reproduce augmented sports videos in a short period, and provides insightful implications for future improvements and opportunities.

Computational Social Science: Visualization in Science of Science
In this big data era, more and more human-related data has been collected. These complex and large-scale data have prompted a series of new research approaches in social science: computational social science. Data visualization is a new method for social scientists to analyze social problems via its high-efficiency model and intuitive designs and interactions.
Seek for Success: A Visualization Approach for Understanding the Dynamics of Academic Careers
Yifang Wang, Tai-Quan Peng, Huihua Lu, Haoren Wang, Xiao Xie, Huamin Qu, and Yingcai Wu
Project Page: wangyifang.top/2021/07/19/paper-acseeker/
How to achieve academic career success has been a long-standing research question in social science research. With the growing availability of large-scale well-documented academic profiles and career trajectories, scholarly interest in career success has been reinvigorated, which has emerged to be an active research domain called the Science of Science (i.e., SciSci). In this study, we adopt an innovative dynamic perspective to examine how individual and social factors will influence career success over time. We propose ACSeeker, an interactive visual analytics approach to explore the potential factors of success and how the influence of multiple factors changes at different stages of academic careers. We first applied a Multi-factor Impact Analysis framework to estimate the effect of different factors on academic career success over time. We then developed a visual analytics system to understand the dynamic effects interactively. A novel timeline is designed to reveal and compare the factor impacts based on the whole population. A customized career line showing the individual career development is provided to allow a detailed inspection. To validate the effectiveness and usability of ACSeeker, we report two case studies and interviews with a social scientist and general researchers.

Data Storytelling: Construct and Enhance Data Stories by Film Theories
A good story structure can enhance the expressiveness of data stories and thus improve audiences’ understanding of data. There are a lot of narrative structures in the field of movies and literature. How to learn from and apply such story structures in the visualization field has brought extensive discussions.
A Design Space for Applying the Freytag’s Pyramid Structure to Data Stories
Leni Yang, Xian Xu, Xingyu Lan, Ziyan Liu, Shunan Guo, Yang Shi, Huamin Qu, Nan Cao
Data stories integrate compelling visual content to communicate data insights in the form of narratives. The narrative structure of a data story serves as the backbone that determines its expressiveness, and it can largely influence how audiences perceive the insights. Freytag’s Pyramid is a classic narrative structure that has been widely used in film and literature. While there are continuous recommendations and discussions about applying Freytag’s Pyramid to data stories, little systematic and practical guidance is available on how to use Freytag’s Pyramid for creating structured data stories. To bridge this gap, we examined how existing practices apply Freytag’s Pyramid by analyzing stories extracted from 103 data videos. Based on our findings, we proposed a design space of narrative patterns, data flows, and visual communications to provide practical guidance on achieving narrative intents, organizing data facts, and selecting visual design techniques through story creation. We evaluated the proposed design space through a workshop with 25 participants. Results show that our design space provides a clear framework for rapid storyboarding of data stories with Freytag’s Pyramid.
