Development and evaluation of a test setup to investigate distance differences in immersive virtual environments

Nowadays, with recent advances in virtual reality technology, it is easily possible to integrate real objects into<br> virtual environments by creating an exact virtual replication and enabling interaction with them by mapping the obtained tracking<br> data of the real to the virtual objects. The primary goal of our study is to develop a system to investigate distance differences for<br> near-field interaction in immersive virtual environments. In this context, the term distance difference refers to the shift between<br> a real object and the respective replication of the real object in the virtual environment of the same size. This could occur<br> for a number of reasons e.g. due to errors in motion tracking or mistakes in designing the virtual environment. Our virtual<br> environment is developed using the Unity3D game engine, while the immersive contents were displayed on an HTC Vive Pro headmounted display. The virtual room shown to the user includes a replication of the real testing lab environment, while one of<br> the two real objects is tracked and mirrored to the virtual world using an HTC Vive Tracker. Both objects are present<br> in the real as well as in the virtual world. To find perceivable distance differences in the near-field, the actual task in the<br> subjective test was to pick up one object and place it into another object. The position of the static object in the virtual<br> world is shifted by values between 0 and 4 cm, while the position of the real object is kept constant. The system is evaluated by<br> conducting a subjective proof-of-concept test with 18 test subjects. The distance difference is evaluated by the subjects through<br> estimating perceived confusion on a modified 5-point absolute category rating scale. The study provides quantitative insights<br> into allowable real-world vs. virtual-world mismatch boundaries for near-field interactions, with a threshold value of around 1 cm.