Abstract-Providing natural hand interaction between a virtualobject and a user on Augmented Reality is a major issue to manipulate a rendered object in a convenient way. Conventional 2D image-based recognition and interaction technique in AR has a limitation to perform a natural interaction between the user and the virtual object. In this paper, we present a stereo-vision based natural 3D hand interaction with the augmented object. In the proposed 3D hand interaction approach, 3D hand location and finger direction can be easily obtained by using stereo-vision technique while user hand is approaching to the virtual object. Two types of hand manipulation for the augmented object such as the hand pointing and hand pinching are defined. The collision detection between user hand and the virtual object is determined by using a simple ray casting emitted from the user's finger-point against the virtual object in the case of hand pointing. In the hand pinching, the collision is occurred when the thumb and the index finger are approaching to the object and the degree of angle between two fingers becomes a predetermined value. From the experiments, the proposed 3D hand interaction method can control the virtual object in a natural way rather than using a vision-based 2D hand interaction since the stereo-vision technique can obtain the depth information from the AR environments.

This paper presents dynamic modelling of a virtual object in augmented reality environments when external forces are applied to the object in real-time fashion. In order to simulate a natural behavior of the object we employ the theory of Newtonian physics to construct motion equation of the object according to the varying external forces applied to the AR object. In dynamic modelling process, the physical interaction is taken placed between the augmented object and the physical object such as a haptic input device and the external forces are transferred to the object. The intrinsic properties of the augmented object are either rigid or elastically deformable (non-rigid) model. In case of the rigid object, the dynamic motion of the object is simulated when the augmented object is collided with by the haptic stick by considering linear momentum or angular momentum. In the case of the non-rigid object, the physics-based simulation approach is adopted since the elastically deformable models respond in a natural way to the external or internal forces and constraints. Depending on the characteristics of force caused by a user through a haptic interface and model's intrinsic properties, the virtual elastic object in AR is deformed naturally. In the simulation, we exploit standard mass-spring damper differential equation so called Newton's second law of motion to model deformable objects. From the experiments, we can successfully visualize the behavior of a virtual objects in AR based on the theorem of physics when the haptic device interact with the rigid or non-rigid virtual object.☞ keyword : Haptic Interaction, Physically-based Modeling, rigid object, elastically deformable model, Augmented Reality

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