Collaborative virtual environments allow remote users to work together in a shared 3D space. To take advantage of the possibilities offered by such systems, their design must allow the users to interact and communicate efficiently. One open question in this field concerns the avatar fidelity of remote partners. This can impact communication between the remote users, more particularly when performing collaborative spatial tasks. In this paper, we present an experimental study comparing the effects of two partner's avatars on collaboration during spatial tasks. The first avatar was based on a 2.5D streamed point-cloud and the second avatar was based on a 3D preconstructed avatar replicating the remote user movements. These avatars differ in their fidelity levels described through two components: visual and kinematic fidelity. The collaborative performance was evaluated through the efficacy of completing two spatial communication tasks, a pointing task and spatial guidance task. The results indicate that the streamed point-cloud avatar permitted a significant improvement of the collaborative performance for both tasks. The subjective evaluation suggests that these differences in performance can mainly be attributed to the higher kinematic fidelity of this representation as compared to the 3D preconstructed avatar representation. We conclude that, when designing spatial collaborative virtual environments, it is important to reach a high kinematic fidelity of the partner's representation while a moderate visual fidelity of this representation can suffice.

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