3D interaction techniques are an essential element of any virtual environment. Their intuitiveness and unobtrusiveness are crucial factors for their acceptance by the end-users. Hence, the selection of the right input devices and interaction methods is important for a successful virtual reality system. VR-OOS aims to provide a flexible and safe environment for planning, analysis and training of on-orbit servicing tasks, and the design and development of a 3D user interface (3D UI) is an important prerequisite. In order to realize this, SC-SRV is developing the necessary components for an effective 3D UI, which includes input devices and interaction techniques for the purpose of manipulation, navigation and system control in the virtual environment.
Fig.: A user grasping a virtual object.
Fig.: A user grasping a virtual object (close up).
Fig.: Two interaction methods exploiting a finger-tracking device.
Selection and manipulation tasks are the most fundamental tasks for both physical and virtual environments. The quality of the input devices and interaction techniques that allow the manipulation of 3D virtual objects has a significant effect on the quality of entire 3DUI. For the purpose of tele-operation tasks, a sophisticated bi-manual haptic feedback device [link] is being developed at the Robotics and Mechatronics Institute. In addition to this, we are investigating different interaction methods, such as the use of a light-weight finger-tracking device, psuedo-haptic and multimodal approaches to improve the selection and manipulation of virtual objects. For instance, we focus on improving finer manipulation stages such as improving awareness of slip when holding a virtual object. These methods are especially useful during scenarios, such as planning, analysis, design review or training using VR-OOS.
Navigation is the process of moving through an environment for exploration or towards a target destination. In virtual environments, navigation usually involves changing the viewpoint within the virtual environment towards the target. Various travel techniques (e.g., gaze-directed steering, pointing/gesture steering, selection) and navigation aids (e.g., 3D maps, WIM, agents) within virtual enviroments have been researched to satisfy different application needs. The design and selection of effective navigation techniques in VR is influenced by factors, such as input devices, system and application level requirements and human factors. Moreover, navigation should be easily integrated with other interaction techniques in the application. In VR-OOS, we explore, design and evaluate navigation techniques using different interaction devices, such as a tracked joystick, gesture based steering using hand tracking or gamepad. For example, we explore how a hand-controlled 'hover' mode can reduce the dependency on buttons on the interaction device.
System control techniques allow us to send commands to an application, change a mode, or modify a parameter. Examples of such techniques for 2D interfaces include pull-down or pop-up menus, toolboxes, palettes, etc. System control interfaces for 3D UI are not trivial and is another important research aspect especially for immersive virtual environments (IVE), such as VR-OOS. In VR-OOS, users have to deal with 6-DOF input opposed to 2-DOF on the desktop. For an effective system control in IVEs, it is critical to allow a continuous interaction flow and preserve the immersion, for instance the user does not want to walk out and press a key on the keyboard or use the mouse just to change a few parameters of the running system. Therefore, we are exploring various multimodal system control techniques that use multiple channels to efficiently control a system from within the immersive virtual environment. These include, for example, 3D menus, speech and gesture.