Advanced interaction techniques in virtual environments

Fundamental to much of the Virtual Reality work is, in addition to high-level 3D graphical and multimedia scenes, research on advanced methods of interaction. The "Visitor" of such virtual worlds must be able to act and behave intuitively, as he would in evryday situations, as well as receive expectabvle natural behaviour presented as feedback from the objects in the environment, in a way that he/she has the feeling of direct interaction with his/her application. In this paper we present several techniques to enrich the naturalness and enhace the user involvement in the virtual environment. We present how the user is enabled to grab objects without using any specific and elaborate hand gesture, which is more inturitive and close to the way humans are used to do. We also introduce a technique that makes it possible for the user to surround objects without any force-feedback interaction device. This technique allows the user to surround or "walk" with the virtual hand on the object's sur face and look for the best position to grab it