User-centered mobile AR design for urban tourism

USER-CENTRED DESIGN OF SMARTPHONE AUGMENTED REALITY IN URBAN TOURISM CONTEXT

Other than the consistent finding that users find it easier to read annotations in small, visual bubbles to help differentiate them from the real world background in the viewfinder - little was known about the mobile AR tourist experience prior to this extensive 2015 study.  From these tests the researcher devised a
​USER-CENTERED DESIGN FRAMEWORK FOR SMARTPHONE AUGMENTED REALITY​

In essence, the framework encourages designers to 
(1) match the perceived physical characteristics (e.g. visibility, visual salience, and legibility) of target objects to ensure usable annotations, and
(2) predict the information needs of users to enhance utility of delivered content.

Interaction triggers with the AR browser and expectations for content 
- Users interpret visual cues about the purpose and importance of a site, or object, and will not interact with the browser if there are no cues to suggest a site's interest. 
- If a site is deemed important, they will expect more content about it. 
- They also need guidance to find sites that are not yet visual in the viewfinder.

Association of virtual annotations and physical targets 
- There has to be at least one (direct or indirect) visual match between the perceived characteristics of the physical target and the AR annotation in order for users to associate them effectively.
- If all annotations have the same visual attributes (layout, the same symbols, same names), it will be harder for users to know which  annotation(s) refer to the target object.  

Information needs and queries
- AR browsers should prioritise delivery of content about visible targets, because this is what tourists are most likely to react to.   
- Attention is limited in busy environments and directed towards visual points of interest, thus the information needs of the user will depend on the visibility of physical targets. Partial visibility might also lead to a different set of assumptions about the target physical object, and therefore impact information needs.  
- If the tourist has learned about the historical and cultural significance of a landmark beforehand, their questions will be different (e.g. Why is this important?), rather than the questions of tourists who do not have this information (e.g. What is this?).     

Embodied interaction and spatial permanence of annotations
Users expect annotations above, or nearby small objects and in the centre of larger spaces.  They also expect moving annotations along the length of a street, rather than only in one place.

User Requirements for AR Annotations
- The perceived function of target objects (e.g. restaurant, historical building) influences the information needs and expectations of tourists. For instance, reviews and ratings are considered necessary, useful and relevant only for specific types of physical objects (e.g. restaurants, cafes, food venues).
- Providing information about non-visible targets (e.g. either a short walk away, or inside buildings) can also enhance situation awareness - but it is helpful if the annotations for visible and non-visible targets are different and that difference is readily apparent.
- It is helpful if virtual annotations match directly at least one of the perceived visual characteristics of the target object on the screen of the smartphone. 
- Changes in visibility (perspective, distance) of target objects should be reflected in the representation of the virtual AR annotation in order to ensure efficient and effective association between them.
- It is especially important to provide content for points of interest that tourists might have learned about from other information sources and consider important.
- Due to user expectations about moving and static target information, different rules need to be set for discrete (e.g. buildings - with explanatory annotations directly above, or next to), continuous linear (e.g. streets, rivers - which may need moving, continuous information) and spatial (e.g. squares - where info can be center screen) entities. 
- There is generally no need to provide information that can already be visually perceived or extracted from the physical environment (e.g. the name of a coffee shop).  
- Useful information helps decision-making and micro-time/journey management such as special (unique), interesting and important location information from a tourist point of view. 
- Tourists ultimately need to acquire information about paths (route knowledge) and the relation among POIs (survey knowledge), therefore it is helpful if they are provided with different location-based interfaces, such as 2D and 3D maps, lists or more traditional tour guide interfaces.
- When screen space is limited, users should be able to infer that they will be able to find those answers by interacting with the smartphone display and sequentially accessing further information about the physical target.


Design Parameters and Taxonomy for AR Browsers
There are three main high-level design parameters that will ultimately impact the usability and perceived utility of AR browsers: (1) abstraction level of base layer (y), (2) abstraction level of attribute layer (x), and (3) amount of information (z). These three design parameters are also inter-connected. A lower level of abstraction means faster and more effective second referential mapping (and overall association of AR annotations and physical targets).    

Design Guidelines for Smartphone AR Browsers
Apart from whole physical structures, various elements of the environment, such as signs, windows, and different architectural elements could attract the attention of the tourist and trigger information needs. 

Satisfying the information needs of tourists
- The primary purpose of the attribute (AR) layer is to capture information that is not present in the physical environment and could not be obtained without the smartphone device.
- Users should have access to choices of display information, as well as easy routes to access further information if they wish, but the screen clutter should be minimised.  Users rarely read longer descriptions for individual annotations when they had to consult the AR display with extended arm.  
- A tappable button that switches on and off the virtual attribute layer for non-visible targets (contextual information) might also be helpful.  
- At the same time, they should be visually salient, attract the attention of the user and increase the desire to learn about the environment. All content should be balanced and merge well with the physical representation of the surroundings (base layer) and the target annotation. 
- Distance-based filtering in AR browsers is not only an under-utilized function, but leads to difficulties and confusion when users want to reduce the amount of annotations on display.  Providing a function that filters out information based on the visbility status of physical entities could prevent such difficulties, save time and be less cognitively demanding for tourists.

Ensuring effective association
- Abstract symbols can take time and effort to process
- Names and keywords can be used if they are physically present and visible from the current location of the user. Pictograms (landmarks) can be used when the target object is a building with a distinctive shape and contour.  
​- Visible graphic variables (e.g. colour, contour) are more suitable to be used as a matching parameter.  As long as it is still clear to identify the link, rendering the real world in a non-photorealistic way using photorealistic virtual models or a colour-coding technique (e.g. matching the colour of a semi-transparent overlay with the colour of the annotation) can also be effective linking strategies.
- Directional pointers can also help to indicate links between annotations and real world objects.

Influence and control over perception of urban environments 
- Designers can use push-based notifications to guide attention.
- Different visualisation techniques that alter the detail of visual panoramas can also be helpful to flag points of interest.
- Keywords such as “interesting”, or “popular”, trigger interest and influence the perception towards specific urban entities​

Yovcheva, Z., 2015. User-centred design of smartphone augmented reality in urban tourism context (Doctoral dissertation, Bournemouth University)