Recently, several VR systems that use wind to enhance users' sensation of presence have been built. In typical systems, simple fans are often used as wind sources and those wind sources are arranged rather sparsely. However, it is not known whether the wind direction is presented precisely enough with such a configuration. In order to find a guideline for optimal arrangement of wind sources, we examined the properties of wind direction perception at the head. We measured the just-noticeable difference (JND) on the perceived wind direction at front of the face using a method of constant stimuli when using a single fan. Among various parameters that might affect the wind direction perception, we focused ourselves on the effect of difference between stimulus parts and wind velocities. The results imply that the alignment of the user's head is important and increased wind velocity might improve perception of wind direction. We also discuss important points when designing a fan-based wind display.
