When multiple users are simultaneously sharing a workspace, it is not always clear what should happen when a user invokes an undo action. We explored different user interfaces for undo/redo for co-located collaborative workspaces, such as large interactive whiteboards. A preliminary study revealed that users expect neither a global nor personal undo, but rather a regional undo. We propose and evaluate three automatic regional undo/redo techniques (clustering, workspace, field of view) designed for a large interactive whiteboard. The results of the evaluation showed that an undo technique based on users’ field of view was most preferred, while the content-based clustering technique produced most errors.
Motivation
Undo/redo is a very common application operation familiar to most users and is seen as an essential functionality, which virtually every desktop application provides. On such single-user systems undo is quite simple to implement and it is quite clear what users expect when they select the undo functionality. In contrast, the undo action on a multi-user interface is more complex – not only from a technical, but also from a user interaction perspective.
When multiple users are working on a document at the same time, it is not always clear what happens if one user invokes an undo action. Until now, this problem of multi-user undo has been addressed in distributed applications (e.g. shared screen editors such as Google Docs). But due to the fact that interactive surfaces are becoming larger and larger, this problem also gains relevance in co-located collaborative work environments like on large Interactive Whiteboards (for example the NiCE Wall).
Automatic Regional Undo Techniques
Clustering
In the clustering technique, items in close proximity are grouped together and define an undo/redo region. Once a user selects an undo action, the cluster closest to the invoked tool palette (containing the undo button) will be chosen. |
Workspace
The workspace technique facilitates the users’ workspace for regional undo. This technique is based on the idea that users occupy a certain workspace on a large interactive surface. |
Field of View
The personal field of view defines the undo region. A tangible tool palette facilitates triggering of undo/redo actions and allows the user to move freely. In our implementation users in front of the interactive surface are identified and their position tracked using Microsoft Kinect. Depending on the distance to the surface the width of their visual field is estimated. |
To get more information about this project have a look into our paper!