Collaborative Virtual Environments (CVEs) offer unique opportunities for human communication. Humans can interact with each other over a distance in any environment and visual embodiment they want. Although deictic gestures are especially important as they can guide other humans' attention, humans make systematic errors when using and interpreting them. Recent work suggests that the interpretation of vertical deictic gestures can be significantly improved by warping the pointing arm. In this paper, we extend previous work by showing that models enable to also improve the interpretation of deictic gestures at targets all around the user. Through a study with 28 participants in a CVE, we analyzed the errors users make when interpreting deictic gestures. We derived a model that rotates the arm of a pointing user's avatar to improve the observing users' accuracy. A second study with 24 participants shows that we can improve observers' accuracy by 22.9%. As our approach is not noticeable for users, it improves their accuracy without requiring them to learn a new interaction technique or distracting from the experience.

We present Yea Big, Yea High - a 3D user interface for surface selection in virtual environments. The interface extends previous selection interfaces that support exploratory visualization and 3D modeling. While these systems primarily focus on selecting single objects, Yea Big, Yea High allows users to select part of a surface mesh, a common task for data analysis, model editing, or annotation. The selection can be progressively refined by physically indicating a region of interest between a user's hands. We describe the design of the interface and key challenges we encountered. We present findings from a case study exploring design choices and use of the system.