TerraFirma: A Low-Cost and Effective 360 VR Extension for Viewpoint Translation and Collaboration.

This paper presents an approach for extending 360 VR to support viewpoint translation and collaboration, without increasing the acquisition cost. The approach models the ground under the 360° image acquisition viewpoint with a planar patch, on which the user stands and walks. The planar patch is connected to the background with visual continuity. The approach anchors the user's avatar to the ground patch, and supports collaboration, with multiple avatars standing on the patch. The approach only requires defining two trivial parameters: the approximate acquisition height, and the size of the patch. Therefore, the approach improves the immersive exploration of a real-world scene captured with a 360° image, without increasing the cost of the acquisition of the virtual environment. The approach was evaluated in a controlled user study (N = 30) with five user t asks. The results show that the approach has an advantage over conventional 360 VR in terms of anchoring the user to the ground, of user viewpoint translation, of collaboration, and of accurate integration of stationary and dynamic virtual objects into the 3D scene.