Virtual environment and its ground surface can influence locomotion while being immersed in virtual reality

Immersive virtual reality (IVR) is an artificially designed environment that can be used to produce realistic and engaging environments which are being used actively in the field of healthcare through training and rehabilitation. The use of IVR nowadays ranges from training surgical operations in a safe environment to neurorehabilitation. IVR implementation for rehabilitation is more task-specific, enhances patients' attention during training, and provides visual feedback. Avatar, a virtual extension of the user, can be used to interact with the virtual environment and aid in postural adjustments during rehabilitation. Although IVR training of upper limbs is often seen, the research is ongoing for lower limbs. Walking activities in the real-world post-stroke are essential for active participation in the community and to reduce potential mental illness. There is ongoing research on how to implement walking activities in VR. This study aimed to explore the effect of visualizing different ground surfaces on gait patterns. Twelve healthy young participants were recruited for the experiment. Two scenes with a different ground surfaces -- ice and concrete -- were designed. A male and a female avatar were animated and implemented in the scene. The participants were asked to walk eight times in both. Trackers located at the left and right foot and pelvis were used to obtain kinematic parameters such as stride and step length and gait speed. The participants were asked to answer an embodiment questionnaire, which consisted of questions about body ownership, sense of agency, and location, after each scene. We found that the first kinematic values of stride and step lengths and gait speed were lower while walking over the virtual ice scene compared to concrete. Overall, the values of body ownership, and sense of agency were higher when compared to the control questions of body ownership and sense of agency, after each scene. The value of the sense of location after each scene was also higher. The present findings show that the participants embodied in both the scenes and the ground surface had a significant influence on their gait modification. Thus, implementing ground surfaces along with IVR in rehabilitation can benefit patients by helping them adapt their gait to the ground surface.Biomedical Engineerin