Orientation and Gesture on Horizontal Displays Russell Kruger, Sheelagh Carpendale Department of Computer Science, University of Calgary, 2500 University Dr. NW, Calgary, Alberta, Canada {sheelagh, krugerj}@cpsc.ucalgary.ca Abstract. Orientation has been recognized as a significant issue for software for horizontal displays. When people stand around a horizontal display, they view the contents from different angles. A common approach to this problem has been to orient objects towards the user who has currently selected them. In contrast, our observational study indicates that there may be many positive uses of variant orientation. Adjusting the orientation of objects can be used to estab- lish personal space, create a public space, and is used as a significant part of gestures that direct comments, ask for help, and indicate interest. Many of these orientation adjustments or gestures are partial in that an angle is chosen some- where between ideal for both people, and temporary in that objects are fre- quently rotated back. This indicates that it may be important to support partial and temporary rotations in order to provide people with the opportunity to use this type of gesturing when collaborating on a tabletop display. 1 Introduction Orientation is frequently a concern when switching from a vertical display to a horizontal display [1,2,4]. It has been seen as a problem on horizontal displays be- cause when people are seated around a horizontal work surface they see objects from different angles. Objects are the ‘right’ way up for some people and not for others. Most approaches to this orientation problem on tabletop displays have tried to orient objects according to the position of the current user. Personal Digital Historian [2] provides a circular tabletop display on which objects are laid out circularly with down considered as away from the centre. No matter from which direction you approach, the closest objects will be right way up for you. In ConnecTables [3], which are formed by linking small personal displays together to create a tiled larger display, objects are oriented in each section for a person located at the base of the section. Also, neural nets have been used to recognize a user’s stylus orientation and use this information to adjust the orientation of the objects when they are selected [1]. Tang [4] has observed that variant orientation on a horizontal work surface is not always a negative factor. He noted the familiar problems of people seeing things at odd angles and having difficulty reading and annotating because of this. However, he also noted that using someone else’s alignment conveyed support, that orientation was used to establish the intended audience, and that orientation was used to create a personal space. In our observational study we see similar uses of orientation. 2 Observational Study In order to get a better understanding of the similarities and differences in how people use physical tables, electronic table-displays and vertical displays, we have