Visual aspects of Augmented Reality

Vision Summit 2016

The International Conference on Augmented Reality, Virtual Reality and Computer Graphics (SALENTO AVR) takes place annually in the city of Otranto in Italy. The main goal of this conference is to bring together researchers, scientists, and practitioners to discuss key issues, approaches, ideas, open problems, innovative applications and trends on virtual and augmented reality, 3D visualization and computer graphics. The main areas of research are in the fields of medicine, cultural heritage, arts, education, entertainment, industrial and military sectors. Some of the currently discussed topics about Augmented Reality of this conference are in the field of the visual aspects of AR or research regarding perceptual issues in AR. [1]

Legibility Issues within Augmented Reality Applications

A lot of newly developed Augmented Reality applications in the industrial environment use Head-Worn Displays (HWDs) to provide the user with technical documentation by adding textual graphics, 3D Models and animations to the screen. A main problem of augmented reality in the industrial sector is the legibility and readability of the text which is displayed with HWDs. Because it is very important to display text-style, colour and illustrations properly, efficient text visualisation is therefore critical for industrial AR applications. Currently there is no standard which defines how text should be displayed via HWDs. Because of that a lot of developers don’t know the optimal text style for specific displays and applications.

According to the literature, legibility of a text depends mainly on the following aspects: background, display technology and text style including font, size and colour. There are currently four approaches how to increase text legibility in AR:

  • Move the text on the display or direct user’s gaze towards high contrast areas.
    • For assembly and maintenance operations, where the user must be focused on the task, this is not very feasible. Some workstations may not afford darker areas of the scene.
  • Modify the text contrast with hardware solutions in the display (e.g. LCD masking)
    • This solution, while the most promising approach, is still in the research stage.
  • Adapt the text color according to the background
    • For industrial applications this is not always feasible because it could violate color-coding guidelines that can be regulated by international standards (e.g. “ASME A13.1, 2007”, “ISO 3864”-Safety Symbols)
  • Employ outline/billboard technique
    • Based on the latest results it is suggested that this is a feasible solution for industrial applications because it the flexibility and the ease of implementation

plain text and billboard

Comparing the two text styles. Plain text on the left, billboard on the right.

The latest research suggests that enhancing text contrast via software, using outline or billboard, is an effective practice to improve legibility in many situations. Maximum contrast styles, like “black text and white billboard” or “white text only” is suggested when the reading time of a scenario is important. In conclusion billboards provide the best performances but at the slight cost of scene occlusion. [2]

 

[1] http://www.salentoavr.it/tracks/#augmented

[2] A. Uva, M. Fiorentino, G. Monno, “Addressing Legibility Issues in Industrial Augmented Reality”, 2014

 

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