Blending the Worlds: World-Fixed Visual Appearances in Automotive Augmented Reality

TL;DR

Blending the Worlds investigates world-fixed POIs in in-car AR using a field study with 38 participants to determine how height, size, rotation, render distance, information density, and appearance affect user experience in a moving vehicle. The system employs a Varjo XR-3 pass-through HMD to render spherical POIs outside the vehicle, with configurable height, size, rotation, render distance, and content density, designed for rear-seat passengers. Key findings establish baseline UX guidelines: position POIs at eye level with distance-based height; use a ~3 m base size with distance-based scaling; prefer billboarding rotation; use an intermediate render fade (around 300 m in urban contexts); and present high information density (name, image, rating, and category icon). Acceptance of in-car AR is generally positive, with pragmatic POI categories for daily-use assistance and entertainment potential for unknown-city exploration; the work provides actionable guidelines for designing passenger-focused in-car AR POIs and points to avenues for extending to more contexts and interactions in future research.

Abstract

With the transition to fully autonomous vehicles, non-driving related tasks (NDRTs) become increasingly important, allowing passengers to use their driving time more efficiently. In-car Augmented Reality (AR) gives the possibility to engage in NDRTs while also allowing passengers to engage with their surroundings, for example, by displaying world-fixed points of interest (POIs). This can lead to new discoveries, provide information about the environment, and improve locational awareness. To explore the optimal visualization of POIs using in-car AR, we conducted a field study (N = 38) examining six parameters: positioning, scaling, rotation, render distance, information density, and appearance. We also asked for intention of use, preferred seat positions and preferred automation level for the AR function in a post-study questionnaire. Our findings reveal user preferences and general acceptance of the AR functionality. Based on these results, we derived UX-guidelines for the visual appearance and behavior of location-based POIs in in-car AR.

Figures (7)

• Figure 1: Our proposed POI visualization in front of a black background. The left POI shows an icon representing a restaurant. The right POI shows a sample restaurant image and a rating from zero to five stars.
• Figure 2: Schematic visualization of participants' field of view during the study. The red lines show the 115° field of view of the Varjo XR-3. The relative position and scale of the POIs and the car in the image are true to scale.
• Figure 3: Schematic representation of POI placement and appearance in the four study conditions regarding height (left) and size (right).
• Figure 4: Schematic representation of the two study conditions manipulating the POIs' rotation (left) and render distance (right).
• Figure 5: Boxplots for scores regarding the height (left) and size (right) conditions. The bold lines indicate the median and the dotted lines indicate the mean. The dependent variables height/size, visibility, and pleasantness are shown grouped by the independent variables as illustrated above the graphs. For height, size, and visibility, values closer to zero are better. For pleasantness, higher values are better.