  Integrating real-time, complex social signal processing into robotic systems
-- especially in real-world, multi-party interaction situations -- is a
challenge faced by many in the Human-Robot Interaction (HRI) community. The
difficulty is compounded by the lack of any standard model for human
representation that would facilitate the development and interoperability of
social perception components and pipelines. We introduce in this paper a set of
conventions and standard interfaces for HRI scenarios, designed to be used with
the Robot Operating System (ROS). It directly aims at promoting
interoperability and re-usability of core functionality between the many
HRI-related software tools, from skeleton tracking, to face recognition, to
natural language processing. Importantly, these interfaces are designed to be
relevant to a broad range of HRI applications, from high-level crowd
simulation, to group-level social interaction modelling, to detailed modelling
of human kinematics. We demonstrate these interface by providing a reference
pipeline implementation, packaged to be easily downloaded and evaluated by the
community.
