Hardware, software, and in particular users now seem ready to engage with computer-generated 3D worlds and the appropriate 3D user interfaces (3D UIs) for interacting with such worlds. 3D UIs have traditionally only been used in very specific application domains such as virtual reality (VR) and augmented reality (AR) environments, digital content creation (DCC) systems, computer-aided design (CAD) systems, visualization systems, and computer games. Now they are beginning to appear in operating systems, on personal digital assistants (PDAs) and mobile phones, and in console gaming systems (e.g., Nintendo's Wii). Even 3D cinema has been given a second chance, and stereoscopic versions of movies are produced on a regular basis. Consequently, new television systems are being equipped with 3D functionality. These examples show that the demand for and the use of 3D UIs is significantly increasing.
The IEEE Symposium on 3D User Interfaces (3DUI) was established in 2006 following two successful workshops—the 2004 workshop "Beyond Wand and Glove Based Interaction" and the 2005 workshop "New Directions in 3D User Interfaces." Today, the 3DUI symposium is the premier conference for all types of 3D user interface research for desktop and off-the-desktop environments, including novel input device designs, interaction techniques, evaluation methods, and user studies.
In this special issue of IJHCS, we are pleased to present extended versions of three outstanding papers that were originally presented at the 3DUI 2007 and 3DUI 2008. An additional paper resulting from an open call was also accepted to this special issue.
The first paper, by Hachet et al. (2009), describes a set of widgets that provide a comprehensive solution for point of interest (POI) navigation in 3D environments. It allows users to quickly navigate to a particular view, explore a 3D scene, or investigate a single object in detail, and it can be used on a variety of display devices. These basic concepts are also extended to other uses beyond navigation alone.
The work by Vanacken et al. (2009) presents two new 3D selection techniques, 3D Bubble Cursor and Depth Ray. Both are targeted at selection in dense and occluded 3D virtual environments. The user studies vary both environment density and target visibility to evaluate the new techniques against a standard 3D point cursor. The effect of auditory and haptic feedback on the selection process is also investigated in a study. The results show that the new techniques enable efficient selection of hidden objects.
The paper by Pusch et al. (2009) presents a new method for providing a pseudo-haptic sensation in an augmented reality setting. The central idea is to displace the virtual representation of the hand from the actual position of the real hand depending on the strength of a virtual flow field. When a user places the hand in a virtual flow field and tries to maintain the hand's position at a cued location, a flow pressure-like sensation is perceived. Experimental results show that different force field strength levels can be discriminated.
Finally, Sharlin et al. (2009) present a novel system and a set of measures for assessing cognitive mapping abilities in the context of a wayfinding task. The hardware setup consists of a projection display for the presentation of virtual environments and a tangible tabletop interface for building a physical model of a seen environment. The cognitive mapping abilities of the users are assessed by recording and analyzing the building progress of the physical model. Since this setup has proven to be sensitive to factors affecting cognitive mapping it allows the computer-supported assessment of this important human ability.
All of these papers contain high-quality contributions to the growing field of 3D user interfaces. We thank the authors for their stimulating work and the reviewers for their constructive and detailed comments.