This paper proposes a novel Redirected Walking technique with inclination manipulation in the roll direction. One of the most critical issues in Virtual Reality is that however large the Virtual Environment is, the user can walk only in the limited space in the real world. Redirected Walking is one of the methods to solve this problem with visual manipulation. In previous studies, manipulations in the yaw and pitch directions were surveyed, but those in the roll directions were not very much. This time, we surveyed basic information about the roll manipulation and proposed a novel method to combine the yaw and roll manipulations. In the first experiment, we estimated the detection threshold of the inclination gain which gradually increased while participants were walking 3m straight. As a result, it is shown that the participants noticed the inclination gain of 1.93° in the left side and 1.39° in the right side. In this experiment, we also found that, when they have presented a large inclination gain, participants tended to walk on a curved path to the same direction as inclination gain. In the second experiment, we investigated the interaction of manipulation in the yaw and roll direction. We found that, when participants have presented an inclination gain, they inclined their head to the same direction and the detection threshold of curvature gain to the same direction became larger.
