GB2233183A

GB2233183A - Imaging system

Info

Publication number: GB2233183A
Application number: GB8913336A
Authority: GB
Inventors: John Hawkins Matthews
Original assignee: GEC Marconi Ltd; Marconi Co Ltd
Current assignee: BAE Systems Electronics Ltd
Priority date: 1989-06-09
Filing date: 1989-06-09
Publication date: 1991-01-02
Also published as: GB8913336D0; EP0402174A1

Description

P/8138/EOPD 1 - IMAGING SYSTEM This invention relates to an imaging system

and to a weapon targetting system including such an imaging S Y stein.

An example of one type of imaging system with which the invention is concerned is a thermal cueing system for use in military aircraft.. In such a system, a thermal. imaging device is directed forward of the aircraft and any high iTitensSty "hot spot.s" in the image which exhibit 1,(.,>mporal and spatial consistency are detected. An image, co.nú;i.st. ing of, for example, arrows indicating the positions of the "but spots" detected is superimposed in the pilot's field of view on a head-up display (11TID) or on a head-down display (I1DD). The pilot must then select a target, perhaps from among several indicated by the arrows, and direct the aim ot a weapons system which includes a second imaging device until the centre ot the image produced by the second imaging device coincides with the selected target.. The weapons system may then be caused to "lock oli" to the target, the w,apoiis system being steered so that the..e I e(-tc-d iinage rintiti.TIS rentred in its field ot view.

F/8138/EOPD 2 This is particularly applicable to laser guided ordnance, where laser guided bombs or missiles -either seek out a laser spot on the ground directed at the target by a weapons system, or follow such a lase beam. The aircraft must carry equipment capable of tracking a ground target and firing a laser accurately pointed at the target. Such equipment is typically referred to as a 'Itargetting pod".

A problem with such systems is that there is an appreciable delay while the pilot directs the targetting pod towards the target selected by the thermal cueing system.

The present invention provides an imaging system having first and second imaging devices and comprising..

object id-entitying means for identifying in the image produced by the first imaging device portions of the image having defined image characteristics, said portions represeiitii-ig objects of possible interest, and for determining the image coordinates for each such object; P/8138/EOPD 3 display means for displaying in association with a view of the scene represented by said image a marker, including an identifying symbol, positioned so as to indicate the location of each object in the scene; selection means whereby an operator may indicate the selection of an object according to its identifying symbol; and means for directing the second imaging device according to the image coordinates for the selected object, whereby the second imaging device produces an image of the selected object.

The first imaging device is preferably a thermal imaging device, while the object identifying means may comprise means for identifying portions of the image above a predetermined intensily which have a predetermined temporal and spatial stability. The display means may comprise an aircraft head-up display or. an aircraft head-down display.

The identifying symbol Lor each object may be a.n u m b er and the selection means m;-iy comprise a keypad whose Ikeys are Individually marked wit.h the identifying P/8138/EOPD - 4 symbols, which may be numbers.

The second imaging device may be a thermal imaging device or a video camera sensitive to visible or near infra-red light. The second 3maging device may have a field of view substantially smaller than that of the first imaging device. The second imaging device may comprise means for directing the line of sight thereof in accordance with the position in the image produced thereby of a selected image feature, whereby the position of said feature in the image may be stabilised.

-W The invention also provides a weapon targetting system, comprising an imaging system according to the invention, and means for aiming a weapon in accordance with the direction of line of sight of the second imaging device.

Reference is made to the drawings, in which:

Figure. 1 shows in diagrammatic form an imaging system in accordance with the invention; and Figure 2 is a diagrammatic representation of a typical. scene as vSewed through the head-up display of P/8138/EOPD - 5 the system as shown in Figure 1.

Referring to Figure 1, the imaging system comprises an infra-red sensor 1 consisting of a thermal imager 2 and a thermal. cuer 3, which receives a video signal from the thermal imager and which detects those pixels in the thermal image which exceed a predetermined intensity and which are positionally stable and which reappear in a predetermined number of successive frames, and therefore have the required temporal stability. The thermal cuer 3 determines the coordinates for each group of pixels conforming with the predetermined requirements and feeds these to a labelling circuit 4 which adds to each set of coordinates an identity "tag" or identifying number. The signal from the thermal imager is also passed to a head-up display 5 via a graphics mixer 6. The head-up display is arranged to superimpose in the line of sight of the pilot looking forward from the aircraft. at least some of the features of the thermal image, and for this reason the thermal. imager js arranged to have a field of view substantially identical to that seen by the pilot.

The signal from the labelling circuit is passed to a symbol geiiei-al.or 7 which generates a graphics display S i gna 1 which is pa-ssed to the graphics mixer 6 so as to -W F/8138/EOPD - 6 add to the thermal image displayed in the head-up display arrows indicating possible targets identified by the thermal cuer together with numbers identifying the different targets. The symbol from the labelling circuit is also passed to a selection and conersion circuit 8 which is arranged to receive a key number from a key pad 9 operable by the pilot to select one of the numbered targets. The selection and conversion circuit 8 responds to the selected key number to select the required coordinates for the object and to convert those coordinates to a pointing angle.

A flip-flop 10 also receives a signal from the key pad when a key is pressed and in response sends a signal to a switch 11 which causes the pointing angle signal from the selection and conversion circuit 8 to be passed to a pointing control 12 in a targetting pod 13.

The targetting pod includes a second thermal imager 14 having a substantially narrower field of view than the thermal imager 2. The thermal ifliager 14 is gimbal mounted with gimba3 motors controlled by signals from the pointing control and with positional feed-back signals returned to the pointing control 12. The targetting pod also contains a targetting laser (not

P/8138/EOPD shown).

The video signal produced by the thermal imager 14 is passed to a tracking control circuit 15 which serves to lock the thermal imager 14 onto the target prsented when the initial positioning signal is received from the selection and conversion circuit 8. When the tracking circuit. is locked onto the target, a pointing angle demand signal is sent by the tracking circuit via the switch 11, a reset signal also being sent by the tracking circuit 15 to the flip-flop 10 which in turn resets the switch 11.

identified by numbers 1, 2 and identified targets. merely to depress the appropriate key of When the targetting pod is locked onto target, It.,he pilot is now presented with imace of the Dotential Figure 2 illustrates diagrammatically a view as seen in the head-up display showing three targets the thermal cuer 3 and indicated by arrows pointing to the To select. a target, the pilot has the key pad.

the selected a stabilised high magnification target, and can decide trom this whether the potential target is an actual target before committing ordnance. It the pilot deci des that the potentidl target is not valid, then he 3 and bv P/8138/EOPD has the ability to select another target by depressing the appropriate key on the key pad. The process then repeats itself.

a P/8138/EOPD

Claims

1. An imaging system having first and second imaging devices and comprising:

object identifying means for identifying in the image produced by the first imaging device portions of the image having defined image characteristics, said portions representing objects of possible interest, and for determining the image coordinates for each such object; display means for displaying in association with a view of the scene represented by said image a marker, including an identifying symbol, positioned so as to indicate the location of each object in the scene; selection means whereby an operator may indicate the selection of an object according to its identifying symbol; and means for directing the second imaging device according to the image coordinates for the selected object, whereby the second imaging device produces an image of the selected object...

i P/8138/EOPD -

2. An imaging system according to Claim 1, wherein the first imaging device is a thermal imaging device.

3. An imaging system according to Claim 2, wherein the object ideiit3fying means comprises means for identifying portions of the image above a predetermined intensity which have a predetermined temporal and spatial stability.

4. An imaging system according to Claim 1, 2 or 3, wherein the display means comprises and aircraft head-up display.

5. An imaging system according to any preceding claim, wherein the identifying symbol is a number.

6. An Imaging system according to any preceding claim, wherein the selection nteans comprises a key pad whose keys whose keys are individually marked with the identifying symbols.

7. An imaging system according to any preceding claim, wherein the second imaging device is a thermal imaging device.

P/8138/EOPD 11

8. An imaging system according to any of Claims 1 to 6, D wherein the second imaging device is a video Pamera sensitive to visible or near intra-red light.

9. An imaging system according to Claim 7 or 8, wherein the second imaging device has a field of view substantially narrower than the first imaging device.

10. An imaging system according to any preceding claim, wherein the second imaging device comprises means for directing the line of sight thereof in accordance with the position in the image produced thereby of a selected image feature, whereby the position of said feature in the image may be stabilised.

11. An imaging system, substantially as described with reference to the drawings.

12. An weapon targetting system, comprising an imaging system according to any preceding claim, and means for aiming a weapon in accordance with the direction of line of sight of the second imaging device.

11). A weapon targei,.t3iig system according to Claim W P/8138/EOPD 12 wherein the means for aiming comprises a laser directed in accordance with the dArection of line of sight of the second imaging device, the weapon ordnance being adapted to follow the path of the laser beam to the target."

Published 1990 a The Patent Office. State House. 66 71 High Holborn, London WC1R4TP.Further copies maybe obtainedfroM The Patent Odrice. Sales Branch. St Mary Cray, Orpington. Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent. Con. 1187