An Improved Surveillance System
Technical Field
The present invention relates to improvements in and relating to surveillance systems. More particularly, although not exclusively, the present invention relates to surveillance systems for use in broad-spectrum applications and where both telephoto and wide-angle surveillance functionality is required.
Background Art There are various instances where surveillance of a particular area may be required and various proposals have been put forward for this purpose. In the case of remote coastlines, there is an increasing need to be able to detect the intrusion into an area of sea of any unauthorised shipping, whether this be for coastguard purposes in detecting smuggling or in a defensive role in detecting possible invasion. Typically, in a marine situation, surveillance will be required over a specified area of sea, scanning the sea up to the horizon.
In a land based situation, the surveillance area could, for example, be a battlefield or a border zone, both of which requiring increasing levels of surveillance with the international reluctance to employ land mines to secure a particular area.
To the present time, it has been known to utilise high-resolution zoom lenses in order to identify an object of interest. However, such zoom lenses have various design constraints, including limited speed and spectral bandwidths which do not extend outside the visual red-green-blue spectrum, which constraints degrading the observational capacity at low light levels.
For example, in the case of a coastguard surveillance of a wide area of sea through an angle of perhaps 1 20°, there may be a need to identify suspect craft. Such craft may be only a few metres long at ranges of several kilometres and, indeed, of course, the craft may be presenting an even smaller width when coming into shore. In such circumstances, such craft may not be detectable in the wide-angle field of a zoom lens, whereas if the lens were
set to a telephoto mode, then the craft would only be detectable within a very narrow field angle.
The present invention provides for an imaging lens which in coastguard surveillance has a long focal length and is very fast (preferably faster than f/1 ) for operation at low light levels and preferably with a spectral band pass extending into the infrared to allow spectral analysis. More specifically and in a preferred embodiment, the present invention utilises the KIWISTAR (Trade Mark) imaging system developed by the present applicant which is described, for example, in New Zealand Patent Specification Nos 236307 and 236308 and International Specification No. PCT/NZ95/00051 .
Numerous other situations, domestic, industrial, military or the like where surveillance of areas is required, will become apparent to those skilled in the relevant arts from the following description.
It is, thus, an object of the present invention to provide a surveillance system which will overcome or at least obviate problems in surveillance systems available to the present time, or which at least will provide the public with a useful choice.
Further objects of this invention will become apparent from the following description.
Disclosure of the Invention
According to one aspect of the present invention, there is provided a surveillance system comprising:
(i) an imaging means; (ii) means for scanning an area under surveillance with said imaging means so that a matrix of contiguous images are obtained; (iii) means for detecting a first image within any of said contiguous images which may be inconsistent with an earlier collected first image; and
(iv) means enabling a specific focusing on an area proximate or corresponding to the first image.
Preferably, the imaging means comprises an ultra-fast high-resolution broad-spectrum long focal length imaging system.
Suitably, a surveillance system as defined in either of the paragraphs immediately above, uses at least two imaging means, a first of which being utilised for scanning the required area and the second of which being used for focusing on a specific image.
According to a further aspect of the present invention, a method of providing surveillance for a required area includes providing at least one imaging means which provides a matrix of contiguous images over the required area and includes means for detecting a change in any one of said images requiring further investigation.
According to a further aspect of the present invention, there is provided a surveillance system and/or method therefor substantially as herein described.
Brief Description of the Drawing Further aspects of this invention which should be considered in all its novel aspects will become apparent from the following description given by way of example of possible embodiments thereof and in which reference is made to the accompanying drawing which shows very diagrammatically a possible use of an embodiment of the invention in coastguard surveillance.
Best Mode for Carrying out the Invention
The present invention will be described particularly in respect of a coastguard surveillance system, but it will be appreciated by those skilled in the relevant arts that the present invention has application wherever surveillance of a particular area may be required.
In the accompanying drawing, one of possibly several surveillance means, a plurality of which could typically be located along a coastline and connected together to a central processing system, is shown very diagrammatically, referenced by arrow 1 . This is
providing surveillance over a particular area of coastline to the horizon, and in doing so, is collecting a matrix of contiguous images which will then be stored, suitably in a large video memory, so that the images are being continually updated, awaiting some change to be detected. As indicated very generally, the scanning can be provided in the manner of a matrix of a number of images for each specified number of rows. It will be appreciated, however, that this is given by way of example only and it may be that the scanning could concentrate on particular areas where surveillance is especially needed and where smuggling or invasion, for example, could likely take place, whereas for other areas of the area under surveillance, images can be taken with lesser frequency.
It is envisaged that the visual memory of the area under surveillance may be suitably programmed so that what is normally present in an image at a particular time of day, a particular tide, a particular time of year, etc. is regarded as the normal image against which the most recent scanned image is then tested for any changes which may be detected.
Where such a change in a particular image is detected, then the imaging means 1 may, it is envisaged, be commanded to stop scanning so that that area can be focused on and the suspect craft identified and suitably tracked. It is envisaged that the imaging means 1 would have the capability of identifying the direction and speed of movement, if any, and may be able to identify a particular type of craft if that was desirable, particularly in a military surveillance system.
In a preferred embodiment of the present invention, at least a pair of imaging means may be provided so that one imaging means may be used for specifically focusing on an area or object found in that area while the other imaging means continues in scanning the overall area under surveillance.
In one example of the present invention, a KIWISTAR (Trade Mark) imaging system of the present applicant could have a focal length of 200mm and a speed f/1 . Such a system would have the capability of detecting a 10 metre length craft side-on at a range of 10km where it would subtend an angle of 1 mr ( 1 milliradian), this requiring the imaging detector to be constructed with pixels of 10μm pitch with the length of the craft fitting into a 20 pixel dimension.
Assuming further, that the imaging detector has dimensions of, for example, 7x9mm, then the angle field of view for 200mm focal length would be 2°x2.6°. Assuming a panorama width, for example, of 130° and a height of 20°, then a matrix of contiguous images would require 10 rows of 50. For 102m square pixels, each of the 500 images would be made up of 700x900 (equals 630000) pixels. The entire matrix would require 31 5Mb of RAM employed as video memory which, of course, would be readily available for this purpose.
In further embodiments of the invention, it is envisaged that there could, for example, be three imaging means with one looking at the whole scene, one scanning and one being used for specific focusing purposes.
It is further envisaged that the present invention could be utilised for aerial scanning, rather than with the imaging means being land or sea based.
Where in the foregoing description, reference has been made to specific components or integers of the invention having known equivalents then such equivalents are herein incorporated as if individually set forth.
Although this invention has been described by way of example and with reference to possible embodiments thereof, it is to be understood that modifications or improvements may be made thereto without departing from the scope of the appended claims.