exploring the past through video traces

TimeLine is an interactive visualization system that creates a composite image of activities captured on video over time. Using this image, people can easily and rapidly detect patterns of interest, and then interactively explore portions of that video history in detail.

The basic method extracts a scan line from each frame as it appears over time in the video stream, and then adds that line to the end of a composite image. The actual video frame is also stored and associated with each line. The image portrays a pattern of events that occured under that line over time. One version of TimeLine lays this out as a weekly calendar, showing visual patterns of events as they occurred over the last minute, hour, day and week.

A person can explore this video history by moving the position of the scan line; the entire composite image immediately displays the patterns derived from this new position. The person can also review the original video frames by scrubbing their cursor over the lines in the image that attracts their interest.

The figure show an example. The red line is positioned over the door in the video scene. The pattern in the composite image reveals people as they walked in and out of that door over the last minute. Scrubbing over a person in that image will 'play back' that part of the video sequence.


Mike Nunes (MSc Student)
Saul Greenberg (Supervisor)
Carl Gutwin and Sheelagh Carpendale (Project Advisors)

Key Publications

Nunes, M., Greenberg, S., Carpendale, S. and Gutwin, C. (2006)
Timeline: Video Traces for Awareness. In Video Proceedings of ACM Conference on Computer Supported Cooperative Work - ACM CSCW'06. ACM Press, November. Video and two page paper, duration 4:44.
PDF Paper Video File
Nunes,M., Greenberg, S., Carpendale, S. and Gutwin, C. (2007)
What Did I Miss? Visualizing the Past through Video Traces. In Proceedings of the European Conference on Computer Supported Cooperative Work - ECSCW'07. (Limerick, Ireland), pages 1-20, September 24-28. Earlier version as Report 2007-875-27. See related ACM CSCW'06 Video.
PDF Paper PowerPoint Presentation

Other Publications

Greenberg, S., Brush, A.J., Carpendale, S., Diaz-Marino, R., Elliot, K., Gutwin, C., McEwan, G., Neustaedter, C., Nunes, M., Smale,S. and Tee, K. (2007)
Collected Posters from the Nectar Annual General Meeting. Research report 2007-887-39, Department of Computer Science, University of Calgary, Calgary, Alberta, Canada, December.
PDF Paper
Nunes, M., Greenberg, S., Carpendale, S. and Gutwin, C. (2006)
Video Traces. In Karahalios, K. and Viegas, F. (Eds.) ACM CHI 2006 Workshop on Social Visualization: Exploring Text, Audio, and Video Interactions. On-line proceedings. Includes video shown at the workshop.
PDF Paper Video File
Nunes, M., Greenberg, S., Carpendale, S. and Gutwin, C. (2006)
Demonstrating Timeline: Video Traces for Awareness. In Demonstration and short paper, Adjunct Proceedings ACM CSCW 2006.
PDF Paper