Interaction Philosophy

Hover UI Kit follows a particular vision for usability and user experience (UX) in virtual reality (VR) and augmented reality (AR) applications. The themes present throughout Hover UI Kit reflect a core philosophy about interactions in virtual environments.

Interaction

Familiar vs. Abstract

Designing interactions for a VR/AR application can be very challenging, and this process almost always requires a balance between the familiar and the abstract. Developers and designers must consider solutions in the context of each application's purpose, genre, audience, user experience, and technical limitations.

	Familiar	Abstract
Traits	Realistic, physical, specialized	Condensed, symbolic, standardized
Benefits	Reduces learning curves Increases intuitiveness Feels "natural"	Improves efficiency Bypasses physical limitations Feels "powerful"
Experience	Increased user motion Physical affordances Direct/manual interaction Flatter/simpler organizations One-to-one ratio with real world	Minimal user motion Dynamic audio/visual affordances Indirect/conceptual interaction Hierarchical/complex organizations Multiplied effect over real world

As a standardized interface system, meant for consistent usage across any scenario, Hover UI Kit tends toward the abstract side of this spectrum. There is an element of the familiar, of course, with the touch-like "hover" interaction to select items, and visual feedback to make interactions discoverable and intuitive.

Consider a "desk" application as an example. Its core interactions are highly familiar: grab the coffee mug to move it, lift a book's cover to open it, hold a pen to draw with it, and so on. Instead of complicating these core interactions, additional features and controls are added via Hover UI Kit interfaces. These non-core interactions are mostly abstract: save and load desk layouts, change the color and size of any item, choose the weather outside, choose the room's decor, search for a particular email, and so on.

Practicality

To be successful, user interactions must always consider technical limitations. This includes the capabilities of the input device, the quality and reliability of that input, the visual quality and depth perception provided by the VR/AR glasses, the lack of haptic or motion-resistant feedback, and so on.

Many interaction ideas seem promising on the conceptual level, but fail on a practical level. This can occur for a variety of interaction types. This does not mean these interactions are inherently bad, it just means that the designer or developer must work around the limitations for each scenario.

Interaction	Limitations	Results
Physical	Input device accuracy Input/physics interplay Physical realism	Users can become disillusioned or frustrated when physical reactions do not occur as expected.
High-Precision	Input device jitter Imperfect depth perception No haptics/friction	Users can have difficulty stabilizing their motion and gauging their target's position.
Gestural	Input device accuracy User performance reliability User training	Users can have difficulty learning gestures and performing them consistently (either physically or virtually).

The interactions in Hover UI Kit strive to be highly practical in the context of the current technical capabilities and limitations. Most 3D input devices can provide at least one reliable point per hand, and this becomes a cursor. From there, no specific pose, gesture, physical collision, or high-precision motion is required. Instead, the cursor must simply move near to an item, then stay there for a moment to complete the interaction.

Pleasantness

It is not enough for user interactions to be functional, they should also be pleasant. This subjective quality -- whether an interaction "feels good" -- is very difficult to define in general terms. It varies based upon the context, the purpose, the audience, and so on.

Crafting a pleasant interaction involves several notable factors. The interaction should be easy to perform, reliable, steady, and produce a result within the realm of user expectation. The user's physical state and ergonomics must be considered, to avoid unnecessary reaching, moving, or straining. The interaction should include dynamic visual cues to help the user discover interactivity and orient themselves in 3D space. And, of course, it involves nuance: smooth animations, reactive elements, and so on -- delightful subtleties that can transform an interaction from feeling mechanical to feeling alive and full of character.

The interfaces and interactions in Hover UI Kit consider all of these factors. From being easy to perform and learn, to providing strong visual cues, to smooth animated transitions -- every feature is built with a pleasant user experience in mind. Of course, in its effort for standardization, Hover UI Kit may miss some opportunities for pleasantness. This is open for customization, however, as each unique application may benefit from different techniques.

Themes

Hover

The hover action is the key interaction element for all interface types. A hover begins when the cursor (for example, a fingertip) moves toward an item. Once the cursor moves within the item's selection threshold, a timer begins. If the cursor stays within the selection threshold for the duration of that timer, a selection event occurs.

Hover actions encourage the use of visual indicators, and make it possible to simplify the requirements for three-dimensional input.

Visual Indicators

Visual indicators communicate important information to the user. They help the user understand where they are in 3D space, their relative location/distance to an object, their progress for an action or gesture, etc.

They also communicate that an item is interactive, guiding the user toward a complete action. This generally improves usability, and reduces the learning curve for new users.

Simple Inputs

With the current state of three-dimensional input devices, the quality of motion tracking can vary greatly based on internal (within the app and computer) and external (the user's real-life environment) factors. Simplified input methods can compensate for potentially unpredictable and inaccurate tracking results. The "hover" action, which only requires one point to move near another point, is a good example.

Three-dimensional input devices are often new and unfamiliar to users, and there are infinite movements, gestures, speeds, and actions the user could possibly perform. Given a lack of standard gestures, and the wide variability in which the user might perform them, it is vital to simplify input for general-use scenarios.