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Data distribution

Data delivery from the analysis was by function call under Windows, limiting the multitasking that could be achieved with low latency. We usually use TCP sockets under Linux, with one object data record being stored in each packet, so that both the bandwidth and the packet rate are predictable and low. This also permits the computer that draws the video overlay to be physically separate (i.e. next to the camera) from the one that controls the hardware (i.e. next to the sensor).

In some cases there are many data users, such as multiple video camera viewpoints being overlaid or a supervisor station, in which case the data records can be delivered using UDP and the broadcast address for the local ethernet segment. Loss of occasional individual data records does not significantly impact the video overlay, since it will extrapolate from available data.

This use of network protocols empowers the local users to structure their environment to meet specific needs, but it is important to either use an isolated network or a local firewall gateway to ensure that the display system cannot be spoofed by a remote attacker and thereby permit a threatening weapon to pass through undetected.

The built-in IP chains/tables support in the Linux kernel permits the system to safely operate autonomously, yet still be on the local network for delivering status reports and other application specific traffic to a central security monitoring station elsewhere in the facility.


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Next: Object Detection Up: Object Reporting Previous: Video Alignment
alex.perry@ieee.org