Designing 3D Interfaces Examples of 3D interfaces Pros and cons of 3D interfaces Overview of 3D software and hardware Four key design issues: system performance, movement, presence, health & safety

What is a 3D interface? Uses 3D graphics, possibly combined with specialised hardware, to give depth or perspective to the display of information Utility: Extended GUIs Realism: Immersive Interfaces Visualisation Virtual Environments Degree of ‘utility versus realism’

Visualisation Adding focus and context to 2D interfaces 3D visualisation of scientific data

Virtual Environments SimulationGames

Pros and cons of 3D Pros: create a sense of presence realistic simulation of physical space and objects more display space through focus + context Cons: additional dimension to manipulate and control hard to map onto 2D displays and devices occlusion difficulty of remembering the locations of information requires greater hardware performance

3D interface software Graphics libraries Objects (polygons and meshes), lighting, textures, animation, collisions, physics (e.g., deformations), special effects (e.g., fog), cameras With scripting User interaction, object behaviours, time-based actions Sound Used for ‘spot effects’, soundtrack, and speech Spatialisation Supporting tools Modelling and animation 2D art work - textures

Specialised 3D interface hardware

Hardware characteristics Output Field of view Resolution Frame rate Stereo or mono Extent of exclusion of physical world (Locally) Shared or individual Degree of encumberance Force Feedback

More hardware characteristics Input Degrees of freedom of movement sensing Range Accuracy Jitter Physical stability (for public use)

Key Design Issues System performance Movement Presence Health and safety

System performance Real-time performance is the often the most vital factor for 3D interfaces Maintain high frame-rate Rapid interaction with minimal latency Download size for online

Movement Up to six DOF required But, the input device may support fewer make frequent movements direct less frequent require special actions - additional mouse buttons, keys or special vehicles but watch out for loss of parallelism - e.g., rotation as a single action Also need to design manipulations – point, select, drag, rotate, resize, carry etc

Presence A mental state where participant has the sense of being in the location specified by the displays - “being there” A fundamental goal of VR? Measuring presence subjective presence behavioural presence

Factors that affect presence Immersion Mode of navigation Self-body image External disruptions Inconsistencies between the user’s mental model of the world and its actual behavior Boredom and amount of activity

Health and Safety Possible effects sickness postural instability psycho-motor coordination Four factors the VR system the virtual environment the user the task

Health & Safety Guidelines maintain frame rate > 20 hz, 8-15 hz may be especially bad keep lag as low as possible don’t use HMD without other present inform users and encourage small head movements avoid awkward postures for sustained periods