3D User Interfaces Flashcards
3D Interaction
- Human-computer interaction in which the user’s tasks are carried out in a 3D spatial context
- 3D input devices, 2D input devices mapping into 3D
3D User Interface (UI)
A UI that involves 3D interaction
3D Interaction technique:
A method (hardware and software) allowing a user to accomplish a task in a 3D UI
What makes 3D Interaction difficult?
Spatial input
Lack of constraints
Lack of standards
Lack of tools
Lack of precision
Fatigue
Layout more complex
Perception
Mine’s Fundamental Forms of Interaction in Virtual Environments
Movement: for a user to move through the virtual world
- Parameters: speed, direction
Selection: ways to indicate the target of the desired interaction
- Requires: Method to 1) identify object of interest (Pointing), 2) Signal or command to indicate act of selection (button press)
Manipulation: Specification of an object’s position and/or orientation in the virtual world.
- Parameters: change in position, change in orientation and center of rotation.
Scaling: to get components at their correct relative score, and allow a user to view some small detail
- Parameters: the center of scaling and the scaling factor
Menu: powerful way to add function to a virtual environment application
- Parameters: Dimensionality (1D, 2D, 3D), among many others
Object Selection: Goals of Selection
- Indicate action on object
- Query object
- Make object active
- Travel to object location
- Set up manipulation
Selection Technique Classification
Simple Virtual Hand Technique
Process
* One-to-one mapping between physical and virtual hands
* Object can be selected by “touching” with virtual hand
* “Natural” mapping
Limitation:
* Only select objects in hand reach
GO-GO Technique
- Arm-extension technique
- Non-linear mapping between physical and virtual hand position
- Local and distant regions (linear < D, non-linear > D)
Ray-Casting Technique
“Laser pointer” attached
to virtual hand
* First object intersected by ray may be selected
* User only needs to control 2 DOFs
Proven to perform well for remote selection
Variants:
* Cone casting
* Snap-to-object rays
Virtual Hand vs Pointer
Virtual hand:
* Direct, physical, natural, resembles the real world
* Fast performance
* As accurate as hand/finger
* Only for reachable objects
* Occlusion of view through own hand
Virtual pointer:
* Interact with out-of-reach objects
* Requires pointing & confirmation
* Slower, but accurate
* Less occlusion
-> Depends on interaction technique, task, …
Image Plane interaction
Object Manipulation: Goals of Manipulation
- Object placement
*Design
*Layout
*Grouping - Tool usage
- Travel
Taxonomy of Manipulation Techniques
Egocentric vs Exocentric metaphor
Common Manipulation Techniques
- Simple virtual hand
- HOMER
- Scaled-world grab
- World-in-miniature
- Gaze + Pinch
Simple Virtual Hand Manipulation
HOMER Technique
H: Hand-Centered
O: Object
M: Manipulation
E: Extending
R: Ray-Casting
- Selection: Ray-casting
- Manipulate: directly with virtual hand
- Include linear mapping to allow wider range of placement in depth
Scaled-World Grab Technique
- Often used w/ occlusion
- At selection, scale user up (or world down) so that virtual hand is actually touching selected object
- User doesn’t notice a change in the image until he moves
World-In-Miniature (WIM) Technique
- “Dollhouse” world held in user’s hand
- Miniature objects can be manipulated directly
- Moving miniature objects affects full-scale objects
- Can also be used for navigation
Gaze + Pinch Interaction
- Hands act: Gaze only indicates targets, but hands manipulate it.
- Target snapping: The target closest to gaze is always selected.
- 1:1 translation: Object moves like hand moves
Design Guidelines
- No single best manipulation technique
- Optimise the interaction technique vs the device/task
- Reduce degrees of freedom, clutching
- Pointing techniques for selection vs grasping technique for manipulation
- Established techniques vs designing a new application-specific method
- Trade-off between technique design vs environmental design
Conclusions
User interface key for good XR experience
* Usability one of the most crucial issues facing VE applications
* Implementation details critical to ensure usability
* Ease of coding not equal to ease of use
* Need 3D user interface techniques
Design for
* Selection/Manipulation
* Navigation
* System control
Follow good design guidelines
* Cannot just implement 2D techniques in XR
