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Mark Ashdown

Publications

There are more details on my Google Scholar page.

Patents

Sharing Data Between Multiple Programs for Collaboration
GB 2479617 (A), published 2011-10-19. Storing structured data in a client-server system for synchronous remote collaboration.

Projected Image Correction System and Correction Information Generation Program
WO 2007139189 (A1), published 2007-12-06. Photometric characterisation and compensation for digital projectors.

Refereed publications

Some Practical Issues with Touch-Based Interfaces
Mark Ashdown, short paper in D-CIS Lab Multitouch Workshop, due in November 2010.

High-Resolution Interactive Displays
Mark Ashdown, Philip Tuddenham, and Peter Robinson, a chapter in Tabletops - Horizontal Interactive Displays, Springer, due in April 2010.
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Effect of Workspace Awareness Support on Distributed Team Collaboration
Mark Ashdown and Yale Song, a poster at Tabletop 2009, Banff, Canada, November 2009.
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Awareness in Synchronous Collaboration between Tabletop and Handheld Displays
Mark Ashdown, a poster at Tabletop 2008, Amsterdam, Netherlands, October 2008.
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Designing Tabletop Interfaces for Asymmetric Distributed Collaboration
Mark Ashdown and Stacey D. Scott, a poster at Tabletop 2007, Newport, Rhode Island, USA, October 2007.
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Asymmetric Synchronous Collaboration Within Distributed Teams
Mark Ashdown and Mary Cummings, 7th International Conference on Engineering Psychology and Cognitive Ergonomics at HCII 2007, Beijing, China, July 2007. Published in Springer Lecture Notes in Artifical Intellgence, LNAI 4562, ISBN 978-3-540-73330-0, pages 245-255.
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Perceptual Photometric Compensation for Projected Images
Mark Ashdown, Imari Sato, Takahiro Okabe, and Yoichi Sato, IEICE Transactions on Information Systems J90-D, 8, pages 2115-2125. This is a journal article based on the paper in MIRU 2006. Note: this paper is in Japanese, and requires extra fonts to view the PDF.
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Perceptual Photometric Compensation for Projected Images
Mark Ashdown, Imari Sato, Takahiro Okabe, and Yoichi Sato, Meeting on Image Recognition and Understanding MIRU 2006 (the main Japanese domestic computer vision conference), Sendai, 19-21 July 2006. Selected as runner-up for the best paper award (There was one best paper, and three runners-up). Note: this paper is in Japanese.
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Robust Content-Dependent Photometric Projector Compensation
Mark Ashdown, Takahiro Okabe, Imari Sato, and Yoichi Sato, Third IEEE International Workshop on Projector-Camera Systems (PROCAMS 2006), New York City, 17 June 2006, in conjunction with the IEEE Computer Society International Conference on Computer Vision and Pattern Recognition (CVPR 2006). Winner of the best paper award.
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Escritoire: A Personal Projected Display
Mark Ashdown and Peter Robinson, IEEE Multimedia Magazine, Volume 12 Number 1, January-March 2005, pages 34-42. Acceptance ratio approximately 25%.
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Remote Collaboration on Desk-Sized Displays
Mark Ashdown and Peter Robinson, Computer Animation and Virtual Worlds, Volume 16 Number 1, February 2005, pages 41-51. We argue that a task space is more important than a person space for many types of remote collboration. We describe the Escritoire desk display system, the software architecture that allows multiple desks to be connected, and user trials we conducted. Participants could use the system for remote collaboration with a minimum of training, and found pen traces useful for gesturing to each other.
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Steerable Projector Calibration
Mark Ashdown and Yoichi Sato, Second IEEE International Workshop on Projector-Camera Systems (PROCAMS 2005), San Diego, California, USA, 25 June 2005, in conjunction with the IEEE Computer Society International Conference on Computer Vision and Pattern Recognition (CVPR 2005). Note: Equation 6 in this paper is wrong - the denominator of the fraction can be discarded, and d_2 should be changed to d_i. It would probably be better to do the least-squares optimization for that part of the algorithm in a different way.
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Combining Head Tracking and Mouse Input for a GUI on Multiple Monitors
Mark Ashdown, Kenji Oka, and Yoichi Sato, CHI 2005 Extended Abstracts, Portland Oregon, USA, 2-7 April 2005. Acceptance ratio 40%.
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Attentive Interfaces for Multiple Monitors
Mark Ashdown and Yoichi Sato, CHI 2005 Workshop on Distributed Display Environments, Portland Oregon, USA, 3 April 2005.
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A Personal Projected Display
Mark Ashdown and Peter Robinson, ACM Multimedia 2004 video demonstration. Acceptance ratio under 50% A 7 minute video showing the Escritoire in use.
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Personal Projected Displays
Mark Ashdown, PhD thesis, University of Cambridge Computer Laboratory, submitted September 2003. Available as Technical Report UCAM-CL-TR-585, March 2004. I have used the technological advances in large display devices, the lack of space in conventional interfaces, the proved manual and cognitive benefits of alternative input systems, and the sparsity of effective real-time remote collaboration systems to motivate the development of a desk-based interface that I call the Escritoire. Overlapping projectors create a display that fills a desk and also has a high resolution region for detailed work, two pens provide bimanual input over the entire area, and an interface like physical paper addresses some of the affordances not provided by the conventional user interface. Multiple desks can be connected to allow remote collaboration and I report the results of tests with single users and collaborating pairs.
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Intelligent Tutoring and Supervised Problem Solving in the Browser
William Billingsley, Peter Robinson, Mark Ashdown, and Chris Hanson, IADIS International Conference on WWW/Internet 2004, Madrid, Spain, 6 - 9 October 2004, pages 806-811.
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Robust Projected Displays for Ubiquitous Computing
Jay W. Summet, Matthew Flagg, Mark Ashdown, Rahul Sukthankar, James M. Rehg, Gregory D. Abowd, Tat Jen Cham, Workshop on Ubiquitous Display Environments, Nottingham, England, 7 September 2004, in conjunction with UbiComp 2004. A summary of several pieces of work on projected displays.
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A Flexible Projector-Camera System for Multi-Planar Displays
Mark Ashdown, Matthew Flagg, Rahul Sukthankar, and James Rehg, Proceedings of IEEE Computer Society Conference on Computer Vision and Pattern Recognition (CVPR) 2004, Volume 2, Washington D.C., USA, 27 June - 2 July 2004, pages II-165 - II-172. Acceptance ratio 29%. We describe how to create a projected display that spans multiple planar surfaces using a single projector and camera whose positions and intrinsic parameters are unknown. We also had a demo at the conference. This paper is based on the Intel tech report below.
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The Escritoire: Remote Collaboration in a Task Space
Mark Ashdown and Peter Robinson, Workshop on Experiential Telepresence, Berkeley, California, USA, 7 November 2003, in conjunction with ACM Multimedia 2003, pages 73-75. I presented poster at the workshop on the use of the Escritoire for remote collaboration and the contrast between the task space it provides and the person space of a conventional video-conference. I also set up a demo of the foveal display using two projectors.
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Experiences Implementing and Using Personal Projected Displays
Mark Ashdown and Peter Robinson, IEEE International Workshop on Projector-Camera Systems (PROCAMS 2003), Nice, France, 12 October 2003, in conjunction with the 9th International Conference in Computer Vision (ICCV 2003). Describes the issues I encountered implementing the Escritoire, and the results of experiments with single users working on their own and with pairs of users collaborating using separate desks. Explains the physical hardware configuration, and the use of commodity 3D video hardware to warp the graphics before projection. Reports the results of user tests and their implications for the design of personal projected display systems.
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A Life-Sized Desk Display for Peripheral Awareness and Remote Collaboration
Mark Ashdown and Peter Robinson, First Research Workshop on Augmented Virtual Reality (AVIR 2003), Geneva, Switzerland, 18-19 September 2003. Extended abstract about the Escritoire, particularly covering the interface issues.
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The Escritoire: A personal projected display
Mark Ashdown and Peter Robinson, Proceedings of the 11th International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision (WSCG 2003), Pilsen, Czech Republic, 3-7 February 2003, pages 33-40. Acceptance ratio 32%. Program available here. The Escritoire combines two overlapping projectors to form a foveal display, allows two pens to be used simultaneously by combining a high-accuracy digitizer with a low-accuracy ultrasonic pen, and allows images, documents and conventional computer displays to be arranged and manipulated on a desk-sized display.
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The Writing's on the Wall: Large, Remotely Controlled Displays
Mark Ashdown and Peter Robinson, Proceedings of the First European Conference on Computer-Supported Collaborative Learning 2001 (Euro-CSCL), Maastricht, Netherlands, 22-24 March 2001, pages 83-88. Describes a custom-made projection display with pointing device that can be used to control standard application programs, and interprets experiences using it as a demonstration tool.
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Other publications

Escritoire2 Project: Conclusions and Future Work
Mark Ashdown, September 2009. This is the fifth and final deliverable for European Commission FP6 Outgoing International Fellowship 21743. This a summary of the work completed in Marie Curie Fellowship 21743, and a list of directions for future research. The domain of urban search and rescue was analysed, a system for synchronous remote collaboration was implemented, experiments were performed, and results were produced. Future work is suggested, particularly on the user interface and on networking issues such as quality of service.
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eStrategies Projects article
A feature article and interview in eStrategies Projects magazine, July 2009, pages 92-96. A digital version of the magazine is available.
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User Experiences with Asymmetric Distributed Collaboration
Mark Ashdown, April 2009. This is the fourth deliverable for European Commission FP6 Outgoing International Fellowship 21743. Description of quantitative and qualitative results from several experiments on the usability of a remote collaboration system. Participants preferred to have workspace awareness support enabled, and it increased the amount of deictic gesturing. Various strategies were used for collaboratively entering reports, and giving directions on the map. Increasing the team size required subordinate personnel to be more autonomous. Participants suggested various enhancements, such as tactile feedback on the handheld device.
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Design of Experiments for Asymmetric Distributed Collaboration
Mark Ashdown, September 2008. This is the third deliverable for European Commission FP6 Outgoing International Fellowship 21743. Design of an experiment to test a system for synchronous collaboration in distributed teams. Tabletop and hand displays were combined to provide sharing of visual information. Experimental participants were placed in an urban search and rescue scenario. Measures were made of the process of collaboration, the product of the teams' work, and the satisfaction of the team members.
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Implementation of Asymmetric Distributed Collaboration
Mark Ashdown, March 2008. This is the second deliverable for European Commission FP6 Outgoing International Fellowship 21743, entitled "Distributed Crisis Management using Remote Collaboration Technologies". A design is presented for a set of interfaces for tabletop and handheld displays that allows maps and schedules to be shared and edited in real-time on various linked devices. Components of the information and events that are transmitted over the network are listed. Also, a 3D world simulation for an urban search and rescue scenario is described.
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Asymmetric Distributed Collaboration in Emergency Response
Mark Ashdown, October 2007. This is the first deliverable for European Commission FP6 Outgoing International Fellowship 21743, entitled "Distributed Crisis Management using Remote Collaboration Technologies". The need for synchronous collaboration between the operational and tactical levels in an emergency response organization is used to motivate research on asymmetric collaboration between large displays in a command centre and small ones in the field. A cognitive task analysis is presented that could be used in the design of such a system. The analysis is based on an urban search and rescue scenario.
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A Flexible Projector-Camera System for Multi-Planar Displays
Mark Ashdown, Matthew Flagg, Rahul Sukthankar, and James Rehg, Intel Research Technical Report IRP-TR-03-14, November 2003. Extends the work described in HP Labs report HPL-2003-24 listed below. We use an uncalibrated projector-camera pair to create ad hoc multi-planar display surfaces. The calibration robustly calculates homographies from minimal information. This technique is also explained in the CVPR 2004 paper above.
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Applications for Multi-Planar Projected Displays
Mark Ashdown, Matthew Flagg, Rahul Sukthankar, and James Rehg, CVPR 2004 Demo.
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Robust Calibration of Camera-Projector System for Multi-Planar Displays
Mark Ashdown and Rahul Sukthankar, Hewlett Packard Cambridge Research Laboratory, Technical Report HPL-2003-24, 2003. Describes a robust method for calibrating a novel system where a single projector creates a display that spans multiple planar surfaces. A variant of structured light is used to find the edges between the surfaces. Robust methods are described for calculating camera to projector homographies from lines, and performing metric rectification of the planes by imaging everyday objects such as postcards. A refined version of this technique is described in the Intel tech report above.
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The Escritoire: A personal projected display for interacting with documents
Mark Ashdown and Peter Robinson, University of Cambridge Computer Laboratory, Technical Report UCAM-CL-TR-538, June 2002. Describes the Escritoire's real-time image warping system, graphical interface, and distributed client-server design. The WSCG 2003 paper above was based on this report.
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Escritoire Poster
Mark Ashdown, 2002. A single-page poster in the Rainbow Group's series.
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Large-Format Computer Interfaces
Mark Ashdown, First Year Ph.D. Report, University of Cambridge, July 2000. Motivates attention on displays with trends in technology, reviews visualisation techniques and novel user interfaces, and reports on current projects dealing with task-centred collaboration. Provides details of the hardware and software created during the first year of the Ph.D. and sets out the plan for the subsequent two years.
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Vitrigraph: Stained Glass Window Designer
Mark Ashdown, B.A. project dissertation, University of Cambridge, June 1999. Explains the design and implementation of Vitrigraph, an application program that allows a non-technical user to design a detailed window with intuitive manipulation of graphical components. Novel data structures and algorithms are used to detect design faults, calculate production costs, and produce realistic ray-traced images.
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Files

Here is a rough collection of images and other files related to my projects. You can browse the files using the links below.