VLDB 2026 Research / reviewers in the wild / expert
Theophanis Tsandilas
dblp:95/5363
· DBLP profile ↗
26ranked-venue papers
11as first author
8since 2021 · last 2025
0000-0002-0158-228XORCID · corroborated
Domains — the database's venue-derived domains; a paper can count in several
Human-computer interaction and ubiquitous computing · 19 · 10 first-author · 3 since 2021Graphics, computer vision, multimedia, augmented reality and games · 6 · 1 first-author · 5 since 2021Databases, data management, data science and information retrieval · 2 · 1 since 2021
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2025 | Sketch2Data: Recovering data from hand-drawn infographics
Anran Qi, Theophanis Tsandilas, Ariel Shamir, Adrien Bousseau |
Comput. Graph. | 2 |
| 2025 | DataGarden: Formalizing Personal Sketches into Structured Visualization TemplatesabstractSketching is a common practice among visualization designers and serves an approachable entry to data visualization for non-experts. However, moving from a sketch to a full fledged data visualization often requires throwing away the original sketch and recreating it from scratch. Our goal is to formalize these sketches, enabling them to support iteration and systematic data mapping through a visual-first templating workflow. In this workflow, authors sketch a representative visualization and structure it into an expressive template for an envisioned or partial dataset, capturing implicit style as well as explicit data mappings. To demonstrate our proposed workflow, we implement DataGarden and evaluate it through a reproduction and a freeform study. We investigate how DataGarden supports personal expression and delve into the variety of visualizations that authors can produce with it, identifying cases that demonstrate the limitations of our approach and discussing avenues for future work. Anna Offenwanger, Theophanis Tsandilas, Fanny Chevalier |
IEEE Trans. Vis. Comput. Graph. | 2 |
| 2024 | STIVi: Turning Perspective Sketching Videos into Interactive TutorialsabstractFor design and art enthusiasts who seek to enhance their skills through instructional videos, following drawing instructions while practicing can be challenging. STIVi presents perspective drawing demonstrations and commentary of prerecorded instructional videos as interactive drawing tutorials that students can navigate and explore at their own pace. Our approach involves a semi-automatic pipeline to assist instructors in creating STIVi content by extracting pen strokes from video frames and aligning them with the accompanying audio commentary. Thanks to this structured data, students can navigate through transcript and in-video drawing, refer to provided highlights in both modalities to guide their navigation, and explore variations of the drawing demonstration to understand fundamental principles. Capucine Nghiem, Adrien Bousseau, Mark Sypesteyn, Jan Willem Hoftijzer, Maneesh Agrawala, Theophanis Tsandilas |
Graphics Interface | 6 |
| 2024 | TimeSplines: Sketch-Based Authoring of Flexible and Idiosyncratic TimelinesabstractTimelines are essential for visually communicating chronological narratives and reflecting on the personal and cultural significance of historical events. Existing visualization tools tend to support conventional linear representations, but fail to capture personal idiosyncratic conceptualizations of time. In response, we built TimeSplines, a visualization authoring tool that allows people to sketch multiple free-form temporal axes and populate them with heterogeneous, time-oriented data via incremental and lazy data binding. Authors can bend, compress, and expand temporal axes to emphasize or de-emphasize intervals based on their personal importance; they can also annotate the axes with text and figurative elements to convey contextual information. The results of two user studies show how people appropriate the concepts in TimeSplines to express their own conceptualization of time, while our curated gallery of images demonstrates the expressive potential of our approach. Anna Offenwanger, Matthew Brehmer, Fanny Chevalier, Theophanis Tsandilas |
IEEE Trans. Vis. Comput. Graph. | 4 |
| 2023 | ProS: data series progressive k-NN similarity search and classification with probabilistic quality guarantees
Karima Echihabi, Theophanis Tsandilas, Anna Gogolou, Anastasia Bezerianos, Themis Palpanas |
VLDB J. | 2 |
| 2022 | Gesture Elicitation as a Computational Optimization ProblemabstractGesture elicitation studies are commonly used for designing novel gesture-based interfaces. There is a rich methodology literature on metrics and analysis methods that helps researchers understand and characterize data arising from such studies. However, deriving concrete gesture vocabularies from this data, which is often the ultimate goal, remains largely based on heuristics and ad hoc methods. In this paper, we treat the problem of deriving a gesture vocabulary from gesture elicitation data as a computational optimization problem. We show how to formalize it as an optimal assignment problem and discuss how to express objective functions and custom design constraints through integer programs. In addition, we introduce a set of tools for assessing the uncertainty of optimization outcomes due to random sampling, and for supporting researchers’ decisions on when to stop collecting data from a gesture elicitation study. We evaluate our methods on a large number of simulated studies. Theophanis Tsandilas, Pierre Dragicevic |
CHI | 1 |
| 2022 | Understanding Multi-View Collaboration between Augmented Reality and Remote Desktop UsersabstractEstablishing an effective collaboration between augmented-reality (AR) and remote desktop users is a challenge because collaborators do not share a common physical space and equipment. Yet, such asymmetrical collaboration configurations are common today for many design tasks, due to the geographical distance of people or unusual circumstances such as a lockdown. We conducted a first study to investigate trade-offs of three remote representations of an AR workspace: a fully virtual representation, a first-person view, and an external view. Building on our findings, we designed ARgus, a multi-view video-mediated communication system that combines these representations through interactive tools for navigation, previewing, pointing, and annotation. We report on a second user study that observed how 12 participants used ARgus to provide remote instructions for an AR furniture arrangement task. Participants extensively used its view transition tools, while the system reduced their reliance on verbal instructions. Arthur Fages, Cédric Fleury, Theophanis Tsandilas |
Proc. ACM Hum. Comput. Interact. | 3 |
| 2021 | StructGraphics: Flexible Visualization Design through Data-Agnostic and Reusable Graphical StructuresabstractInformation visualization research has developed powerful systems that enable users to author custom data visualizations without textual programming. These systems can support graphics-driven practices by bridging lazy data-binding mechanisms with vector-graphics editing tools. Yet, despite their expressive power, visualization authoring systems often assume that users want to generate visual representations that they already have in mind rather than explore designs. They also impose a data-to-graphics workflow, where binding data dimensions to graphical properties is a necessary step for generating visualization layouts. In this paper, we introduce StructGraphics, an approach for creating data-agnostic and fully reusable visualization designs. StructGraphics enables designers to construct visualization designs by drawing graphics on a canvas and then structuring their visual properties without relying on a concrete dataset or data schema. In StructGraphics, tabular data structures are derived directly from the structure of the graphics. Later, designers can link these structures with real datasets through a spreadsheet user interface. StructGraphics supports the design and reuse of complex data visualizations by combining graphical property sharing, by-example design specification, and persistent layout constraints. We demonstrate the power of the approach through a gallery of visualization examples and reflect on its strengths and limitations in interaction with graphic designers and data visualization experts. Theophanis Tsandilas |
IEEE Trans. Vis. Comput. Graph. | 1 |
| 2020 | Data Series Progressive Similarity Search with Probabilistic Quality GuaranteesabstractExisting systems dealing with the increasing volume of data series cannot guarantee interactive response times, even for fundamental tasks such as similarity search. Therefore, it is necessary to develop analytic approaches that support exploration and decision making by providing progressive results, before the final and exact ones have been computed. Prior works lack both efficiency and accuracy when applied to large-scale data series collections. We present and experimentally evaluate a new probabilistic learning-based method that provides quality guarantees for progressive Nearest Neighbor (NN) query answering. We provide both initial and progressive estimates of the final answer that are getting better during the similarity search, as well suitable stopping criteria for the progressive queries. Experiments with synthetic and diverse real datasets demonstrate that our prediction methods constitute the first practical solution to the problem, significantly outperforming competing approaches. Anna Gogolou, Theophanis Tsandilas, Karima Echihabi, Anastasia Bezerianos, Themis Palpanas |
SIGMOD Conference | 2 |
| 2019 | Comparing Similarity Perception in Time Series VisualizationsabstractA common challenge faced by many domain experts working with time series data is how to identify and compare similar patterns. This operation is fundamental in high-level tasks, such as detecting recurring phenomena or creating clusters of similar temporal sequences. While automatic measures exist to compute time series similarity, human intervention is often required to visually inspect these automatically generated results. The visualization literature has examined similarity perception and its relation to automatic similarity measures for line charts, but has not yet considered if alternative visual representations, such as horizon graphs and colorfields, alter this perception. Motivated by how neuroscientists evaluate epileptiform patterns, we conducted two experiments that study how these three visualization techniques affect similarity perception in EEG signals. We seek to understand if the time series results returned from automatic similarity measures are perceived in a similar manner, irrespective of the visualization technique; and if what people perceive as similar with each visualization aligns with different automatic measures and their similarity constraints. Our findings indicate that horizon graphs align with similarity measures that allow local variations in temporal position or speed (i.e., dynamic time warping) more than the two other techniques. On the other hand, horizon graphs do not align with measures that are insensitive to amplitude and y-offset scaling (i.e., measures based on z-normalization), but the inverse seems to be the case for line charts and colorfields. Overall, our work indicates that the choice of visualization affects what temporal patterns we consider as similar, i.e., the notion of similarity in time series is not visualization independent. Anna Gogolou, Theophanis Tsandilas, Themis Palpanas, Anastasia Bezerianos |
IEEE Trans. Vis. Comput. Graph. | 2 |
| 2018 | Shape-Aware Material: Interactive Fabrication with ShapeMeabstractMakers often create both physical and digital prototypes to explore a design, taking advantage of the subtle feel of physical materials and the precision and power of digital models. We introduce ShapeMe, a novel smart material that captures its own geometry as it is physically cut by an artist or designer. ShapeMe includes a software toolkit that lets its users generate customized, embeddable sensors that can accommodate various object shapes. As the designer works on a physical prototype, the toolkit streams the artist's physical changes to its digital counterpart in a 3D CAD environment. We use a rapid, inexpensive and simple-to-manufacture inkjet printing technique to create embedded sensors. We successfully created a linear predictive model of the sensors' lengths, and our empirical tests of ShapeMe show an average accuracy of 2 to 3 mm. We present two application scenarios for modeling multi-object constructions, such as architectural models, and 3D models consisting of multiple layers stacked one on top of each other. ShapeMe demonstrates a novel technique for integrating digital and physical modeling, and suggests new possibilities for creating shape-aware materials. Michael Wessely, Theophanis Tsandilas, Wendy E. Mackay |
UIST | 2 |
| 2018 | Fallacies of Agreement: A Critical Review of Consensus Assessment Methods for Gesture ElicitationabstractDiscovering gestures that gain consensus is a key goal of gesture elicitation. To this end, HCI research has developed statistical methods to reason about agreement. We review these methods and identify three major problems. First, we show that raw agreement rates disregard agreement that occurs by chance and do not reliably capture how participants distinguish among referents. Second, we explain why current recommendations on how to interpret agreement scores rely on problematic assumptions. Third, we demonstrate that significance tests for comparing agreement rates, either within or between participants, yield large Type I error rates (>40% for α =.05). As alternatives, we present agreement indices that are routinely used in inter-rater reliability studies. We discuss how to apply them to gesture elicitation studies. We also demonstrate how to use common resampling techniques to support statistical inference with interval estimates. We apply these methods to reanalyze and reinterpret the findings of four gesture elicitation studies. Theophanis Tsandilas |
ACM Trans. Comput. Hum. Interact. | 1 |
| 2016 | How Novices Sketch and Prototype Hand-Fabricated ObjectsabstractWe are interested in how to create digital tools to support informal sketching and prototyping of physical objects by novices. Achieving this goal first requires a deeper understanding of how non-professional designers generate, explore, and communicate design ideas with traditional tools, i.e., sketches on paper and hands-on prototyping materials. We describe a study framed around two all-day design charrettes where participants perform a complete design process: ideation sketching, concept development and presentation, fabrication planning documentation and collaborative fabrication of hand-crafted prototypes. This structure allows us to control key aspects of the design process while collecting rich data about creative tasks, including sketches on paper, physical models, and videos of collaboration discussions. Participants used a variety of drawing techniques to convey 3D concepts. They also extensively manipulated physical materials, such as paper, foam, and cardboard, both to support concept exploration and communication with design partners. Based on these observations, we propose design guidelines for CAD tools targeted at novice crafters. Adrien Bousseau, Theophanis Tsandilas, Lora Oehlberg, Wendy E. Mackay |
CHI | 2 |
| 2016 | Stretchis: Fabricating Highly Stretchable User InterfacesabstractRecent advances in materials science research allow production of highly stretchable sensors and displays. Such technologies, however, are still not accessible to non-expert makers. We present a novel and inexpensive fabrication method for creating Stretchis, highly stretchable user interfaces that combine sensing capabilities and visual output. We use Polydimethylsiloxan (PDMS) as the base material for a Stretchi and show how to embed stretchable touch and proximity sensors and stretchable electroluminescent displays. Stretchis can be ultra-thin (≈ 200μm), flexible, and fully customizable, enabling non-expert makers to add interaction to elastic physical objects, shape-changing surfaces, fabrics, and the human body. We demonstrate the usefulness of our approach with three application examples that range from ubiquitous computing to wearables and on-skin interaction. Michael Wessely, Theophanis Tsandilas, Wendy E. Mackay |
UIST | 2 |
| 2015 | SketchSliders: Sketching Widgets for Visual Exploration on Wall DisplaysabstractWe introduce a mobile sketching interface for exploring multi-dimensional datasets on wall displays. We demonstrate the idea of SketchSliders, range sliders that users can freely sketch on a mobile surface to customize their exploration. A small combination of sketches and gestures allows the creation of complex interactive sliders, such as circular sliders for periodic data, slider branches for detailed interaction, and fisheye transformation sliders. We augment sliders with a suite of tools, such as markers, slider cursors, and approximate views of data distributions. Our designs are inspired by a design study with three visualization experts and validated through a user study with six experts using our system. Our findings indicate that our sketching interface accommodates a wide range of exploration strategies, helping users customize as well as focus their visual explorations. Theophanis Tsandilas, Anastasia Bezerianos, Thibaut Jacob |
CHI | 1 |
| 2014 | Structured observation with polyphony: a multifaceted tool for studying music compositionabstractContemporary music composition is a highly creative and disciplined activity that requires free expression of ideas and sophisticated computer programming. This paper presents a technique for structured observation of expert creative behavior, as well as Polyphony, a novel interface for systematically studying all phases of computer-aided composition. Polyphony is a unified user interface that integrates interactive paper and electronic user interfaces for composing music. It supports fluid transitions between informal sketches and formal computer-based representations. We asked 12 composers to use Polyphony to compose an electronic accompaniment to a 20-second instrumental composition by Anton Webern. All successfully created a complete, original composition in an hour and found the task challenging but fun. The resulting dozen comparable snapshots of the composition process reveal how composers both adapt and appropriate tools in their own way. Jérémie Garcia, Theophanis Tsandilas, Carlos Agón, Wendy E. Mackay |
Conference on Designing Interactive Systems | 2 |
| 2014 | Prospective motor control on tabletops: planning grasp for multitouch interactionabstractSubstantial amount of research in Psychology has studied how people manipulate objects in the physical world. This work has unveiled that people show strong signs of prospective motor planning, i.e., they choose initial grasps that avoid uncomfortable end postures and facilitate object manipulation. Interactive tabletops allow their users great flexibility in the manipulation of virtual objects but to our knowledge previous work has never examined whether prospective motor control takes place in this context. To test this, we ran three experiments. We systematically studied how users adapt their grasp when asked to translate and rotate virtual objects on a multitouch tabletop. Our results demonstrate that target position and orientation significantly affect the orientation of finger placement on the object. We analyze our results in the light of the most recent model of planning for manipulating physical objects and identify their implications for the design of tabletop interfaces. \ Halla B. Olafsdottir, Theophanis Tsandilas, Caroline Appert |
CHI | 2 |
| 2014 | Coordination of tilt and touch in one- and two-handed useabstractOur goal is to enhance navigation in mobile interfaces with quick command gestures that do not make use of explicit mode-switching actions. TilTouch gestures extend the vocabulary of navigation interfaces by combining motion tilt with directional touch. We consider sixteen directional TilTouch gestures that rely on tilt and touch movements along the four main compass directions. An experiment explores their effectiveness for both one-handed and two-handed use. Results identify the best combinations of TilTouch gestures in terms of performance, motor coordination, and user preferences. Theophanis Tsandilas, Caroline Appert, Anastasia Bezerianos, David Bonnet |
CHI | 1 |
| 2013 | Modeless Pointing with Low-Precision Wrist Movements
Theophanis Tsandilas, Emmanuel Dubois 0001, Mathieu Raynal |
INTERACT (3) | 1 |
| 2013 | The drawing assistant: automated drawing guidance and feedback from photographsabstractWe present an interactive drawing tool that provides automated guidance over model photographs to help people practice traditional drawing-by-observation techniques. The drawing literature describes a number of techniques to %support this task and help people gain consciousness of the shapes in a scene and their relationships. We compile these techniques and derive a set of construction lines that we automatically extract from a model photograph. We then display these lines over the model to guide its manual reproduction by the user on the drawing canvas. Finally, we use shape-matching to register the user's sketch with the model guides. We use this registration to provide corrective feedback to the user. Our user studies show that automatically extracted construction lines can help users draw more accurately. Furthermore, users report that guidance and corrective feedback help them better understand how to draw. Emmanuel Iarussi, Adrien Bousseau, Theophanis Tsandilas |
UIST | 3 |
| 2012 | Interactive paper substrates to support musical creationabstractWe present paper substrates, interactive paper components that support the creation and manipulation of complex musical data. Substrates take different forms, from whole pages to movable strips, and contain or control typed data representations. We conducted participatory design sessions with five professional musicians with extensive experience with music creation tools. All generated innovative uses of paper substrates, manipulating their data, linking multiple representation layers and creating modular, reusable paper elements. The substrates reflect the structure of their computer-based data, but in a much more flexible and adaptable form. We use their prototypes to provide concrete examples of substrates, identify their roles, properties and functions. Finally, we explore their physical and interaction design with an interactive prototype. Jérémie Garcia, Theophanis Tsandilas, Carlos Agón, Wendy E. Mackay |
CHI | 2 |
| 2012 | Interpreting strokes on paper with a mobile assistantabstractDigital pen technology has allowed for the easy transfer of pen data from paper to the computer. However, linking handwritten content with the digital world remains a hard problem as it requires the translation of unstructured and highly personal vocabularies into structured ones that computers can easily understand and process. Automatic recognition can help to this direction, but as it is not always reliable, solutions require the active cooperation between users and recognition algorithms. This work examines the use of portable touch-screen devices in connection with pen and paper to help users direct and refine the interpretation of their strokes on paper. We explore four techniques of bi-manual interaction that combine touch and pen-writing, where user attention is divided between the original strokes on paper and their interpretation by the electronic device. We demonstrate the techniques through a mobile interface for writing music that complements the automatic recognition with interactive user-driven interpretation. An experiment evaluates the four techniques and provides insights about their strengths and limitations. Theophanis Tsandilas |
UIST | 1 |
| 2010 | Knotty gestures: subtle traces to support interactive use of paperabstractWe introduce the knotty gesture, a simple yet powerful technique for interacting with paper. Knots are tiny circles that can be added to any gesture. Users can leave subtle marks that permit both immediate interaction in the flow of writing and create rich opportunities for future interaction. We identify diverse applications of knotty gestures and explore alternative techniques for interacting with their traces. We conducted two experiments to evaluate the design and recognition heuristics and demonstrated that people can successfully execute knotty gestures, even without feedback. Knotty gestures provide users with a subtle, in-the-flow-of-writing technique for tagging information and subsequently interacting with the paper. Theophanis Tsandilas, Wendy E. Mackay |
AVI | 1 |
| 2009 | Musink: composing music through augmented drawingabstractWe focus on the creative use of paper in the music composition process, particularly the interaction between paper and end-user programming. When expressing musical ideas, composers draw in a precise way, not just sketch. Working in close collaboration with composers, we designed Musink to provide them with a smooth transition between paper drawings and OpenMusic, a flexible music composition tool. Musink's built-in recognizers handle common needs, such as scoping and annotation. Users can also define new gestures and associate them with their own or predefined software functions. Musink supports semi-structured, delayed interpretation and serves as a customizable gesture browser, giving composers significant freedom to create their own, individualized composition languages and to experiment with music, on-paper and on-line. Theophanis Tsandilas, Catherine Letondal, Wendy E. Mackay |
CHI | 1 |
| 2007 | Bubbling menus: a selective mechanism for accessing hierarchical drop-down menusabstractThis paper introduces bubbling menus, a new design for cascading drop-down menus. Bubbling menus combine the bubble cursor [10] with directional mouse-gesture techniques to facilitate the access of certain items in a menu, such as frequently selected items. Through an extensive iterative design process, we explore bubbling menus in the context of adaptive and customizable user interfaces. Unlike other adaptation and customization techniques such as split menus, bubbling menus do not disrupt the original structure of menus and enable the activation of menus far from a menu bar. Results from two evaluation studies presented in the paper show that bubbling menus provide an effective alternative to accelerate menu selections tasks. Theophanis Tsandilas, m. c. schraefel |
CHI | 1 |
| 2005 | An Evaluation of Techniques for Reducing Spatial Interference in Single Display Groupware
Theophanis Tsandilas, Ravin Balakrishnan |
ECSCW | 1 |