In redirected walking techniques, curvature gain and bending gain, which are referred to as curvature manipulation, are important redirection gains. The applied gains can differ when multiple paths are mapped, and sudden changes in gain may cause discomfort. This study proposes quadratic curvature manipulation (QCM) based on the habituation mechanism to effectively reduce discomfort. This method quadratically adjusts the path curvature, thereby reducing user's perception of curvature changes. Furthermore, we introduce the segmented curvature change (SCC) mode that combines QCM with linear curvature manipulation to facilitate more natural gain transitions, thereby reducing discomfort. Two experiments were conducted. Experiment 1 examined the relationship between QCM parameters and gains at which users felt discomfort. Experiment 2 further examined the effects of different curvature change modes on discomfort. The results indicate that using the SCC mode in curvature manipulations is more effective than other methods in reducing discomfort.

Panoramic roaming with HMDs provides an immersive VR experience and the realism of user’s navigation in panoramic virtual environments (VEs) can be further enhanced by real-walking locomotion technology. However, the mismatched viewpoint height & fluctuation with the user’s visual senses may lead to perceptual conflicts during real-walking interaction. We conducted a series of user studies to investigate how viewpoint height & fluctuation affect the walking perception of users by real-walking interaction to navigate panoramic VEs and constructed a virtual camera motion model of viewpoint fluctuation and eyetracking compensation for walking behavior in panoramic virtual roaming. It was found that mismatched viewpoint fluctuation triggered generalized discomfort in participants and that participants preferred virtual viewpoint heights below eye level when roaming in panoramic VEs by real-walking. Considering these findings, we proposed viewpoint adaptive adjustment method based on visual manipulation and conducted a preliminary evaluation, which showed that the proposed method can effectively mitigate the conflict between the visual system and other sensory systems. It made that panoramic VEs constructed at a certain fixed height are rendered universal for users with different eyelevel heights and viewpoint fluctuation is matched to the undulation of their center of gravity during real-walking interaction.

Summary Reaction time, the ability to detect, process and respond to stimuli, is one of the fundamental factors in human computer interaction, and is a key cognitive skill in clinical and healthy populations. Good reaction time allows us to respond to stimuli and situations with agility and efficiency. How to train and improve a person's reaction time has become an important research question. In this paper, we present a new training genre which combines the user‐centered personalized training objects generation with precise tracking of foot interaction.Virtual objects are created with respect to the user's features and historical training effectiveness, and are in motion. A foot tracking algorithm based on three‐Gaussian model is designed to support interaction with stepping on moving virtual objects. We present the design and implementation of the system, as well as user studies. Findings illustrate that the reaction time performances are significantly improved following of seven days of training based on foot interaction.