  The health status of elderly subjects is highly correlated to their
activities together with their social interactions. Thus, the long term
monitoring in home of their health status, shall also address the analysis of
collaborative activities. This paper proposes a preliminary approach of such a
system which can detect the simultaneous presence of several subjects in a
common area using Kinect depth cameras. Most areas in home being dedicated to
specific tasks, the localization enables the classification of tasks, whether
collaborative or not. A scenario of a 24 hours day shrunk into 24 minutes was
used to validate our approach. It pointed out the need of artifacts removal to
reach high specificity and good sensitivity.
