VLDB 2026 Research / reviewers in the wild / expert
David Ledo
dblp:77/10579
· DBLP profile ↗
22ranked-venue papers
6as first author
11since 2021 · last 2026
0000-0002-0455-7936ORCID · corroborated
Domains — the database's venue-derived domains; a paper can count in several
Human-computer interaction and ubiquitous computing · 22 · 6 first-author · 11 since 2021Graphics, computer vision, multimedia, augmented reality and games · 2 · 1 since 2021
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2026 | Protosampling: Enabling Free-Form Convergence of Sampling and Prototyping through Canvas-Driven Visual AI GenerationabstractAs an emergent process, creativity relies on explorations via sampling and prototyping for problem construction. These activities compile knowledge, provide a context enveloping the solution, and answer questions. With Generative AI, practitioners can go beyond sampling existing media towards instantly generating and remixing new ones. We refer to this convergence as ’protosampling’. Using existing literature we ground a definition for protosampling and operationalize it through Atelier, a canvas-like system that leverages a variety of generative image and video models for visual creation. Atelier: (1) blends the spaces for thinking and creation, where both references and generated assets co-exist in one space, (2) provides various encapsulated technical workflows that focus on the activity at hand, and (3) enables navigating emergence through interactive visualizations, smart search, and collections. Protosampling as a lens reframes creative work to emphasize the process itself and how seemingly disjointed thoughts can tightly interweave into a final solution. Alicia Guo, David Ledo, George W. Fitzmaurice, Fraser Anderson |
CHI | 2 |
| 2026 | PrevizWhiz: Combining Rough 3D Scenes and 2D Video to Guide Generative Video PrevisualizationabstractIn pre-production, filmmakers and 3D animation experts must rapidly prototype ideas to explore a film’s possibilities before full-scale production, yet conventional approaches involve trade-offs in efficiency and expressiveness. Hand-drawn storyboards often lack spatial precision needed for complex cinematography, while 3D previsualization demands expertise and high-quality rigged assets. To address this gap, we present PrevizWhiz, a system that leverages rough 3D scenes in combination with generative image and video models to create stylized video previews. The workflow integrates frame-level image restyling with adjustable resemblance, time-based editing through motion paths or external video inputs, and refinement into high-fidelity video clips. A study with filmmakers demonstrates that our system lowers technical barriers for film-makers, accelerates creative iteration, and effectively bridges the communication gap, while also surfacing challenges of continuity, authorship, and ethical consideration in AI-assisted filmmaking. Erzhen Hu, Frederik Brudy, David Ledo, George W. Fitzmaurice, Fraser Anderson |
CHI | 3 |
| 2025 | Generative Rotoscoping: A First-Person Autobiographical Exploration on Generative Video-to-Video Practices
David Ledo |
Creativity & Cognition | 1 |
| 2025 | Paratrouper: Exploratory Creation of Character Cast Visuals Using Generative AIabstractJoanne Leong, David Ledo, Thomas Driscoll, Tovi Grossman, George Fitzmaurice, and Fraser Anderson. 2025. Paratrouper: Exploratory Creation of Character Cast Visuals Using Generative AI. In Proceedings of the 2025 CHI Conference on Human Factors in Computing Systems (CHI '25). Association for Computing Machinery, New York, NY, USA, Article 189, 1–20. Joanne Leong, David Ledo, Thomas Driscoll, Tovi Grossman, George W. Fitzmaurice, Fraser Anderson |
CHI | 2 |
| 2024 | TimeTunnel: Integrating Spatial and Temporal Motion Editing for Character Animation in Virtual RealityabstractEditing character motion in Virtual Reality is challenging as it requires working with both spatial and temporal data using controls with multiple degrees-of-freedom. The spatial and temporal controls are separated, making it difficult to adjust poses over time and predict the effects across adjacent frames. To address this challenge, we propose TimeTunnel, an immersive motion editing interface that integrates spatial and temporal control for 3D character animation in VR. TimeTunnel provides an approachable editing experience via KeyPoses and Trajectories. KeyPoses are a set of representative poses automatically computed to concisely depict motion. Trajectories are 3D animation curves that pass through the joints of KeyPoses to represent in-betweens. TimeTunnel integrates spatial and temporal control by superimposing Trajectories and KeyPoses onto a 3D character. We conducted two studies to evaluate TimeTunnel. In our quantitative study, TimeTunnel reduced the amount of time required for editing motion, and saved effort in locating target poses. Our qualitative study with domain experts demonstrated how TimeTunnel is an approachable interface that can simplify motion editing, while still preserving a direct representation of motion. Qian Zhou 0009, David Ledo, George W. Fitzmaurice, Fraser Anderson |
CHI | 2 |
| 2024 | StoryVerse: Towards Co-authoring Dynamic Plot with LLM-based Character Simulation via Narrative PlanningabstractAutomated plot generation for games enhances the player’s experience by providing rich and immersive narrative experience. Recent advancements use Large Language Models (LLMs) to drive the behavior of virtual characters, allowing plots to emerge from interactions between characters and their environments. However, the emergent nature of such decentralized plot generation makes it difficult for authors to direct plot progression. We propose a novel plot creation workflow that mediates between a writer’s authorial intent and the emergent behaviors from LLM-driven character simulations, through a novel authorial structure called “abstract acts”. Writers create high-level plot outlines which are transformed into character actions via an LLM-based narrative planning process, based on the game world state. This results in narratives co-created by the author, the simulated characters, and the player. We present StoryVerse as a proof-of-concept system to demonstrate the workflow, and showcase its versatility across various stories and game environments. Yi Wang 0048, Qian Zhou 0009, David Ledo |
FDG | 3 |
| 2023 | Immersive Sampling: Exploring Sampling for Future Creative Practices in Media-Rich, Immersive SpacesabstractCreative practitioners rely on sampling to understand, explore, and construct problems; or gather resources for later use. Despite practitioners’ ability to experience immersive environments, sampling from them remains limited to primarily visual captures (e.g., screenshots, videos), which overlook the richness and variety of available media. To address these challenges, we describe “Immersive Sampling” as a new way to frame information gathering in the context of immersive environments. In the context of Immersive Sampling, practitioners engage in experiencing immersive environments while capturing, organizing, revisiting, and remixing found content. We situate this subset of tasks in literature and argue for their importance for emerging, future content creation domains. To further explore how Immersive Sampling might take place, we created VRicolage, a proof-of-concept prototype showcasing a set of interactions in Virtual Reality to sample, revisit, and remix captures. Given the democratization of immersive environments, Immersive Sampling provides practitioners with a means to collect, revisit, and remix digital materials. Evgeny Stemasov, David Ledo, George W. Fitzmaurice, Fraser Anderson |
Conference on Designing Interactive Systems | 2 |
| 2023 | Escapement: A Tool for Interactive Prototyping with Video via Sensor-Mediated Abstraction of TimeabstractWe present Escapement, a video prototyping tool that introduces a powerful new concept for prototyping screen-based interfaces by flexibly mapping sensor values to dynamic playback control of videos. This recasts the time dimension of video mock-ups as sensor-mediated interaction. Molly Jane Pearce Nicholas, Nicolai Marquardt, Michel Pahud, Nathalie Henry Riche, Hugo Romat, Christopher Collins 0001, David Ledo, Rohan Kadekodi, Badrish Chandramouli, Ken Hinckley |
CHI | 7 |
| 2022 | MoodCubes: Immersive Spaces for Collecting, Discovering and Envisioning Inspiration MaterialsabstractIn early stages of creative processes, practitioners externalize and combine inspirational materials, using strategies such as mood board creation to achieve a desired vision and aesthetic. Yet, collecting and combining materials can be difficult: (1) mood boards bias towards 2D images, neglecting audio, video, and 3D models; (2) alternative externalizations such as prototypes are best suited for later stages and can be time-consuming and tedious to create; and (3) online searches lead to disjointed sources between different websites and assets in the file system. To address these challenges, we created MoodCubes, a system for rapid creation and manipulation of multimedia content. When adding content, MoodCubes decomposes objects (e.g., extracting colour palettes), suggests new materials without the need to search (e.g., 3D models, images, lighting effects), and provides filters to change the scene’s aesthetic. We studied eight creative professionals using MoodCubes, which suggested ways the system might advance existing design practices. Alexander Ivanov 0004, David Ledo, Tovi Grossman, George W. Fitzmaurice, Fraser Anderson |
Conference on Designing Interactive Systems | 2 |
| 2022 | "I don't want to feel like I'm working in a 1960s factory": The Practitioner Perspective on Creativity Support Tool AdoptionabstractWith the rapid development of creativity support tools, creative practitioners (e.g., designers, artists, architects) have to constantly explore and adopt new tools into their practice. While HCI research has focused on developing novel creativity support tools, little is known about creative practitioner’s values when exploring and adopting these tools. We collect and analyze 23 videos, 13 interviews, and 105 survey responses of creative practitioners reflecting on their values to derive a value framework. We find that practitioners value the tools’ functionality, integration into their current workflow, performance, user interface and experience, learning support, costs and emotional connection, in that order. They largely discover tools through personal recommendations. To help unify and encourage reflection from the wider community of CST stakeholders (e.g., systems creators, researchers, marketers, educators), we situate the framework within existing research on systems, creativity support tools and technology adoption. Srishti Palani, David Ledo, George W. Fitzmaurice, Fraser Anderson |
CHI | 2 |
| 2021 | AirConstellations: In-Air Device Formations for Cross-Device Interaction via Multiple Spatially-Aware ArmaturesabstractAirConstellations supports a unique semi-fixed style of cross-device interactions via multiple self-spatially-aware armatures to which users can easily attach (or detach) tablets and other devices. In particular, AirConstellations affords highly flexible and dynamic device formations where the users can bring multiple devices together in-air — with 2–5 armatures poseable in 7DoF within the same workspace — to suit the demands of their current task, social situation, app scenario, or mobility needs. This affords an interaction metaphor where relative orientation, proximity, attaching (or detaching) devices, and continuous movement into and out of ad-hoc ensembles can drive context-sensitive interactions. Yet all devices remain self-stable in useful configurations even when released in mid-air. Nicolai Marquardt, Nathalie Henry Riche, Christian Holz 0001, Hugo Romat, Michel Pahud, Frederik Brudy, David Ledo, Chunjong Park, Molly Jane Pearce Nicholas, Teddy Seyed, Eyal Ofek, Bongshin Lee, William Buxton, Ken Hinckley |
UIST | 7 |
| 2020 | Learning Multiple Mappings: an Evaluation of Interference, Transfer, and Retention with Chorded Shortcut ButtonsabstractTouch interactions with current mobile devices have limited expressiveness. Augmenting devices with additional degrees of freedom can add power to the interaction, and several augmentations have been proposed and tested. However, there is still little known about the effects of learning multiple sets of augmented interactions that are mapped to different applications. To better understand whether multiple command mappings can interfere with one another, or affect transfer and retention, we developed a prototype with three pushbuttons on a smartphone case that can be used to provide augmented input to the system. The buttons can be chorded to provide seven possible shortcuts or transient mode switches. We mapped these buttons to three different sets of actions, and carried out a study to see if multiple mappings affect learning and performance, transfer, and retention. Our results show that all of the mappings were quickly learned and there was no reduction in performance with multiple mappings. Transfer to a more realistic task was successful, although with a slight reduction in accuracy. Retention after one week was initially poor, but expert performance was quickly restored. Our work provides new information about the design and use of chorded buttons for augmenting input in mobile interactions. Carl Gutwin, Carl Hofmeister, David Ledo, Alix Goguey |
Graphics Interface | 3 |
| 2020 | SurfaceFleet: Exploring Distributed Interactions Unbounded from Device, Application, User, and TimeabstractKnowledge work increasingly spans multiple computing surfaces. Yet in status quo user experiences, content as well as tools, behaviors, and workflows are largely bound to the current device-running the current application, for the current user, and at the current moment in time. SurfaceFleet is a system and toolkit that uses resilient distributed programming techniques to explore cross-device interactions that are unbounded in these four dimensions of device, application, user, and time. As a reference implementation, we describe an interface built using SurfaceFleet that employs lightweight, semi-transparent UI elements known as Applets. Applets appear always-on-top of the operating system, application windows, and (conceptually) above the device itself. But all connections and synchronized data are virtualized and made resilient through the cloud. For example, a sharing Applet known as a Portfolio allows a user to drag and drop unbound Interaction Promises into a document. Such promises can then be fulfilled with content asynchronously, at a later time (or multiple times), from another device, and by the same or a different user. Frederik Brudy, David Ledo, Michel Pahud, Nathalie Henry Riche, Christian Holz 0001, Anand Waghmare, Hemant Bhaskar Surale, Marcus Peinado, Xiaokuan Zhang, Shannon Joyner, Badrish Chandramouli, Umar Farooq Minhas, Jonathan Goldstein, William Buxton, Ken Hinckley |
UIST | 2 |
| 2019 | Astral: Prototyping Mobile and Smart Object Interactive Behaviours Using Familiar ApplicationsabstractAstral is a prototyping tool for authoring mobile and smart object interactive behaviours. It mirrors selected display contents of desktop applications onto mobile devices (smartphones and smartwatches), and streams/remaps mobile sensor data to desktop input events (mouse or keyboard) to manipulate selected desktop contents. This allows designers to use familiar desktop applications (e.g. PowerPoint, AfterEffects) to prototype rich interactive behaviours. Astral combines and integrates display mirroring, sensor streaming and input remapping, where designers can exploit familiar desktop applications to prototype, explore and fine-tune dynamic interactive behaviours. With Astral, designers can visually author rules to test real-time behaviours while interactions take place, as well as after the interaction has occurred. We demonstrate Astral's applicability, workflow and expressiveness within the interaction design process through both new examples and replication of prior approaches that illustrate how various familiar desktop applications are leveraged and repurposed. David Ledo, Jo Vermeulen, Sheelagh Carpendale, Saul Greenberg, Lora Oehlberg, Sebastian Boring |
Conference on Designing Interactive Systems | 1 |
| 2019 | WatchPen: Using Cross-Device Interaction Concepts to Augment Pen-Based InteractionabstractPen-based input is often treated as auxiliary to mobile devices. We posit that cross-device interactions can inspire and extend the design space of pen-based interactions into new, expressive directions. We realize this through WatchPen, a smartwatch mounted on a passive, capacitive stylus that: (1) senses the usage context and leverages it for expression (e.g., changing colour), (2) contains tools and parameters within the display, and (3) acts as an on-demand output. As a result, it provides users with a dynamic relationship between inputs and outputs, awareness of current tool selection and parameters, and increased expressive match (e.g., added ability to mimic physical tools, showing clipboard contents). We discuss and reflect upon a series of interaction techniques that demonstrate WatchPen within a drawing application. We highlight the expressive power of leveraging multiple sensing and output capabilities across both the watch-augmented stylus and the tablet surface. Michael Yuk-Shing Hung, David Ledo, Lora Oehlberg |
MobileHCI | 2 |
| 2019 | WatchPen: Using Cross-Device Interaction Concepts to Augment Pen-Based InteractionabstractWatchPen illustrates how cross-device interactions can inspire and extend the design space of pen-based interactions into new, expressive directions. We demonstrate WatchPen, a smartwatch mounted on a passive, capacitive stylus that: (1) senses the usage context and leverages it for expression (e.g., changing colour), (2) contains tools and parameters within the display, and (3) acts as an on-demand output. As a result, it provides users with a dynamic relationship between inputs and outputs, awareness of current tool selection and parameters, and increased expressive match (e.g., added ability to mimic physical tools, showing clipboard contents). Our demonstration includes a series of interaction techniques within a drawing application. Michael Yuk-Shing Hung, Lora Oehlberg, David Ledo |
MobileHCI | 3 |
| 2018 | Evaluation Strategies for HCI Toolkit ResearchabstractToolkit research plays an important role in the field of HCI, as it can heavily influence both the design and implementation of interactive systems. For publication, the HCI community typically expects toolkit research to include an evaluation component. The problem is that toolkit evaluation is challenging, as it is often unclear what 'evaluating' a toolkit means and what methods are appropriate. To address this problem, we analyzed 68 published toolkit papers. From our analysis, we provide an overview of, reflection on, and discussion of evaluation methods for toolkit contributions. We identify and discuss the value of four toolkit evaluation strategies, including the associated techniques that each employs. We offer a categorization of evaluation strategies for toolkit researchers, along with a discussion of the value, potential limitations, and trade-offs associated with each strategy. David Ledo, Steven Houben, Jo Vermeulen, Nicolai Marquardt, Lora Oehlberg, Saul Greenberg |
CHI | 1 |
| 2017 | Pineal: Bringing Passive Objects to Life with Embedded Mobile DevicesabstractInteractive, smart objects-customized to individuals and uses-are central to many movements, such as tangibles, the internet of things (IoT), and ubiquitous computing. Yet, rapid prototyping both the form and function of these custom objects can be problematic, particularly for those with limited electronics or programming experience. Designers often need to embed custom circuitry; program its workings; and create a form factor that not only reflects the desired user experience but can also house the required circuitry and electronics. To mitigate this, we created Pineal, a design tool that lets end-users: (1) modify 3D models to include a smart watch or phone as its heart; (2) specify high-level interactive behaviours through visual programming; and (3) have the phone or watch act out such behaviours as the objects' "smarts". Furthermore, a series of prototypes show how Pineal exploits mobile sensing and output, and automatically generates 3D printed form-factors for rich, interactive, objects. David Ledo, Fraser Anderson, Ryan M. Schmidt, Lora Oehlberg, Saul Greenberg, Tovi Grossman |
CHI | 1 |
| 2015 | STRATOS: Using Visualization to Support Decisions in Strategic Software Release PlanningabstractSoftware is typically developed incrementally and released in stages. Planning these releases involves deciding which features of the system should be implemented for each release. This is a complex planning process involving numerous trade-offs-constraints and factors that often make decisions difficult. Since the success of a product depends on this plan, it is important to understand the trade-offs between different release plans in order to make an informed choice. We present STRATOS, a tool that simultaneously visualizes several software release plans. The visualization shows several attributes about each plan that are important to planners. Multiple plans are shown in a single layout to help planners find and understand the trade-offs between alternative plans. We evaluated our tool via a qualitative study and found that STRATOS enables a range of decision-making processes, helping participants decide on which plan is most optimal. Bon Adriel Aseniero, Tiffany Wun, David Ledo, Günther Ruhe, Anthony Tang 0001, Sheelagh Carpendale |
CHI | 3 |
| 2015 | Proxemic-Aware Controls: Designing Remote Controls for Ubiquitous Computing EcologiesabstractRemote controls facilitate interactions at-a-distance with appliances. However, the complexity, diversity, and increasing number of digital appliances in ubiquitous computing ecologies make it increasingly difficult to: (1) discover which appliances are controllable; (2) select a particular appliance from the large number available; (3) view information about its status; and (4) control the appliance in a pertinent manner. To mitigate these problems we contribute proxemic-aware controls, which exploit the spatial relationships between a person's handheld device and all surrounding appliances to create a dynamic appliance control interface. Specifically, a person can discover and select an appliance by the way one orients a mobile device around the room, and then progressively view the appliance's status and control its features in increasing detail by simply moving towards it. We illustrate proxemic-aware controls of assorted appliances through various scenarios. We then provide a generalized conceptual framework that informs future designs of proxemic-aware controls. David Ledo, Saul Greenberg, Nicolai Marquardt, Sebastian Boring |
MobileHCI | 1 |
| 2012 | The fat thumb: using the thumb's contact size for single-handed mobile interactionabstractModern mobile devices allow a rich set of multi-finger interactions that combine modes into a single fluid act, for example, one finger for panning blending into a two-finger pinch gesture for zooming. Such gestures require the use of both hands: one holding the device while the other is interacting. While on the go, however, only one hand may be available to both hold the device and interact with it. This mostly limits interaction to a single-touch (i.e., the thumb), forcing users to switch between input modes explicitly. In this paper, we contribute the Fat Thumb interaction technique, which uses the thumb's contact size as a form of simulated pressure. This adds a degree of freedom, which can be used, for example, to integrate panning and zooming into a single interaction. Contact size determines the mode (i.e., panning with a small size, zooming with a large one), while thumb movement performs the selected mode. We discuss nuances of the Fat Thumb based on the thumb's limited operational range and motor skills when that hand holds the device. We compared Fat Thumb to three alternative techniques, where people had to precisely pan and zoom to a predefined region on a map and found that the Fat Thumb technique compared well to existing techniques. Sebastian Boring, David Ledo, Xiang 'Anthony' Chen, Nicolai Marquardt, Anthony Tang 0001, Saul Greenberg |
Mobile HCI | 2 |
| 2012 | The HapticTouch toolkit: enabling exploration of haptic interactionsabstractIn the real world, touch based interaction relies on haptic feedback (e.g., grasping objects, feeling textures). Unfortunately, such feedback is absent in current tabletop systems. The previously developed Haptic Tabletop Puck (HTP) aims at supporting experimentation with and development of inexpensive tabletop haptic interfaces in a do-it-yourself fashion. The problem is that programming the HTP (and haptics in general) is difficult. To address this problem, we contribute the Haptictouch toolkit, which enables developers to rapidly prototype haptic tabletop applications. Our toolkit is structured in three layers that enable programmers to: (1) directly control the device, (2) create customized combinable haptic behaviors (e.g., softness, oscillation), and (3) use visuals (e.g., shapes, images, buttons) to quickly make use of these behaviors. In our preliminary exploration we found that programmers could use our toolkit to create haptic tabletop applications in a short amount of time. David Ledo, Miguel A. Nacenta, Nicolai Marquardt, Sebastian Boring, Saul Greenberg |
TEI | 1 |