Distance estimation with mixed real and virtual targets in stereoscopic displays

• Accuracy of exocentric distance estimation in augmented reality were studied.
• Layout, parallax and center-to-center distance influence the accuracy of estimation.
• Observers generally underestimated center-to-center distance.
• Accuracy improved as real and virtual targets presented vertical and closer to observer.
• Underestimation raised a question whether real environment was dominated by virtual.

In this paper we investigated the accuracy of center-to-center distance perception in near field augmented reality visual targets viewed by stereoscopic glasses. One real and one virtual targets were presented in four layout or target orientations (two horizontal and two vertical, by altering the relative positions of real and virtual targets) at three different parallax conditions (on screen, 5 cm from screen and 10 cm from screen) and four levels of scaled between targets’ distance (10–20 cm, 20–30 cm, 30–40 cm and 40–50 cm). The result revealed overall underestimation with an accuracy of about 84%. Interestingly, it was noticed that the main effects of layout, parallax and center-to-center distance were significant. Generally, accuracy improves when targets put vertical, close to observers’ position and smaller separation of targets. Significant interactions among the three main factors were also reported. The results are of great importance as it provides guide for the developers to decide where to present targets depending on the need for relative accuracy of judgment. Some engineering implications of the result are also discussed in this paper.