VIH Real-Time Camera Control Demonstrator

The VIH provides a CORBA framework for passing selection and control requests from Remote Users. The delivery of digital video services is the responsibility of the underlying NRTS network.

The VIH allows a variety of Users, including police operators, Highways Agency employees and representatives to select any available camera connected to the VIH and enable real time camera control, preset control and remote viewing facilities. The VIH allows commercial organisations (with an interest in travel information) the ability to access motorway CCTV images.

Objectives
The RTCCD (Real-Time Camera Control Demonstrator) was produced as part of the VIH project and provides a partial simulation of the CORBA framework with the following objectives:

• To prove the concept of real-time CCTV camera control over CORBA
• To measure network and other latencies in the system
• Measure network and other latencies under various loading conditions
• To establish the level of loading at which the timing constraints are no longer met ('breaking point').

Implementation
The RTCCD is made up of two components - a server which simulates the TVBS (Television Base Station) server and a client simulating a TVBS client. The RTCCD system implements the syntactic elements of the CORBA framework, supporting CCTV camera PTZ (pan, tilt, zoom) control and also provides for loading of the network with realistically sized CORBA messages for the other functionality provided by the TVBS.

The RTCCD integrated with several different ORBs (Object Request Brokers) from different manufacturers to also enable an assessment and performance analysis of the implementations provided by the different ORBs and ORB manufacturers. Delay time was measured at 8 key points including entry to ORB, exit from ORB, exit from Ethernet card.

Operator interaction with the control panel - a joystick - causes transmission of instructions via the RS485/RS232 link to the RTCCD client. A 10-stage proportional control was implemented, meaning that the speed of the PTZ motion increased as the joystick was moved further from its origin with the motion accelerating towards the edges. This information is then passed via CORBA to the RTCCD Server.

The PTZ functions are controlled by the RTCCD Server via a further RS-485 link via and RX-232/485 converter. The RTCCD Server translates incoming commands from the CORBA interface to Pan-tilt-zoom protocol commands to instruct movement of the PTZ unit. The RTCCD client and server may be co-located - which facilitates the taking of timing measurements (accurate to 1 millisecond) and control of the loading of the network or may be located a great distance apart and operated over, say, the Internet.

Results
The project successfully proved the concept of real-time camera control using CORBA and provided data for analysis of the performance on the CORBA interface under various loading conditions.