Monitoring, protecting, detecting and identifying, day and night, around a ship or platform
This case study addresses the situation of a complete surveillance around a ship using a high-level solution enabling short, medium or long range detection. Several camera configurations can be developed to provide permanent or semi-permanent 360° coverage for distances ranging from 500 m to 5 km. These performance characteristics can be achieved using a series of fixed-angle cameras, pan-tilt-zoom cameras, semi-panoramic or panoramic cameras, or an appropriate combination of these various camera types.
The detection range is directly linked to the characteristics of the camera’s focal length. As an example, a camera with a horizontal field of vision (HFOV) of 50° is capable of seeing a target measuring 5 x 2 metres (small craft) at 1000 metres (requires a minimum of 2 pixels for detection by the ASV module), while a camera with a field of 30° can see up to 1700 metres, one with a field of 15° approximately 3000 metres, and one with a field of 10° up to approximately 5000 metres.
The compromises to be considered in this configuration are horizontal coverage, desired detection distance and envisaged budget on the one hand and fixed camera network versus scanning camera network on the other hand:
- 360° coverage with a detection range of 3000 metres for a small craft requires 24 fixed-angle cameras with an HFOV of 15° or three to five pan-tilt-zoom cameras, or one rotating camera;
- panoramic fixed or scanning cameras provide an unchanging view, but have limited zoom capability for identification; conversely, pan-tilt-zoom cameras used in scanning mode allow a semi-permanent view of a dedicated space, but provide zoom capability into an object detected so as to enable more precise identification.
- To obtain a permanent view of a sector of interest, it may be advisable to use a combination of fixed-angle and pan-tilt-zoom cameras to optimise coverage while still maintaining satisfactory identification capability.