GB2105157A

GB2105157A - Simulation of a field of view with target and background

Info

Publication number: GB2105157A
Application number: GB08224695A
Authority: GB
Inventors: Dr Robert Stickel
Original assignee: Honeywell GmbH
Current assignee: Honeywell GmbH
Priority date: 1981-08-27
Filing date: 1982-08-27
Publication date: 1983-03-16
Also published as: DE3133866A1; DE3133866C2; FR2512236A1; FR2512236B1

Abstract

In a battle training simulator, the image of a landscape and background is stored in memory 16 and that of a movable target, e.g. a tank, in memory 18. A memory 19 may store the graticule of a gunsight. For each pixel in memories 16 and 18, shade and range are stored digitally. As the raster of a monitor (not shown) is scanned, for each pixel logic circuit 25 decides whether the target appears in front of landscape objects or behind them. The combination image, combined with the graticule via gate 26 is converted to an analogue video signal for input to the monitor. <IMAGE>

Description

SPECIFICATION Simulation of a field of view with target and background The present invention relates to apparatus for simulation of a visual field of view wherein a background image is displayed on a TV monitor and a moveable target is cut-in in that background. Such apparatus is especially used on devices for training of a battle situation.

A method for producing a background image is known wherein an image on a monitor may be produced as a random partial cutout from an overall image. The selection of the partial cutout is made for instance by address producing means coupled to control handles by which portions of individual images may be called up and put together to a partial cutout. These individual images may be digitally stored and it is possible to cut in silhouettes or images of certain objects as, for instance, of moveable targets into the background image displayed on the monitor according to the addressed partial cutout. Generation of those silhouettes or images herewith in a known manner is done by a computer. If such a monitor is arranged in the field of view of the optics of a gunner or commander, then, for instance, a battle situation for tank crews may be simulated.

It is an object of the present invention to improve a method for simulation of a visual field of a view of the previously mentioned species in such a manner that the battle situation may be simulated much more closely to reality.

Accordingly the invention provides apparatus for simulation of a field of view wherein a background image is displayed on a TV monitor and the image of a moveable target is cut-in in that background, and wherein the background and target images are digitally stoed and are displayed after conversion into a video signal, characterized in that individual objects in the background image are provided with digital range information and that, image point by image point, the range information with respect to the individual object is compared with a digital range information of the target in order to determine, object point by image point, whether the target is covered by the individual object or is to be displayed in front of that individual object.

An embodiment of the invention will be described, by way of example, with reference to the drawings, in which Figure 1 is a block diagram of CSI (Computer Synthesized Imagery) apparatus; Figure 2 is a further block diagram of the image selection and the image combination; Figure 3 is a block diagram of the generation of a target course; Figure 4 is an illustration of the monitor image appearing in the field of view; Figure 5 is a schematical illustration of Figure 4 with individual objects arranged at different distances; and Figure 6 is a sketch explaining the evaluation of the range of individual objects by means of targets moveable in the background.

Referring to Figure 1, a system image computer 10 controls the whole system. To this computer, for instance, the address signals are applied which are derived from control handles (not shown). This computer controls background memories 13, 13'...via an interface 11 and memory managing unit 12 with an image of a background being stored in these memories. Cutouts from the background image may be selected by the signals of the control handles. Further a panel (not shown) is coupled to the computer by which certain stored targets may be called up and a course may be provided for the targets.

The background video information digitally stored in the background memory 13, 13' is applied to a monitor memory 16 and a first monitor control unit 17 via image busses 14, 14' under control of a control bus 15. Asecond monitor control unit 17' as well as further such units may be arranged according to the number of monitors so that at the same time a plurality of persons may be trained. The monitors not shown in Figure 1 are arranged in the field of view of the optics of a gunner or commander, whereby the screen just fits into the field of view of the viewing optics.

Besides the cutout from the background image stored in the monitor memory 16, an image of the target and an image of a reticle are stored in a target memory 18 and a sight memory 19. The sight memory 19 may also store the rotational position or any other information with respect to for instance a tank vehicle. A monitor managing unit 20 controls the memory assignment. Further on, a concentrating computer 22, connected via an interface 1 to the system image 10, takes over a subordinate assignment of the individual monitor control units 17, 17' etc, via a further control and data bus 15'.

After combining the contents of all three memory units 16, 18 and 19 in an image mixer 21, as well as after converting the digital image information into a analog video information over separate outputs Al and A2, the monitors are controlled which are assigned to the gunner respectively the commander. Through a control by means of the control handles it is possible to track the moveable target with the reticle whereby the cutout of the background image experiences a continuous change. The gunner or commander, therefore, get the impression of a battle situation very close to reality at his view of the monitor screen arranged in the field of view of his optics.

Figure 2 shows details of the system of Figure 1. A central TV clock generator 23 controls x and y address generators 24a and 24b. The address generators 24a and 24b for instance are formed by digital angle encoders coupled to the control handles and they select via an x-bus 14a and a y-bus 14b by means of the address a predetermined cutout from the background image. Further, the target and the sight are added to the background. According to an essential feature of the present system, each image point of the background and of the target is digitally encoded by a plurality of bits with respect to its grey level GH, Gz (5 bits), and with respect to its range EH, Ez (3 bits).Therefore, a decision logic 25 is able to determine whether with a present target (Gz > 0) this target is to be displayed in front of an individual object (house, bush, forest) in the background EH > EZ) or behind that individual object (EH > EZ). After combining of an accordingly selected image point with the reticle and after a following digital/analog conversion, display of the mixed image is presented on the monitor.

Figure 3 shows an extension of the system according to Figure 1 with the possibility of generating a target course. By means of a control handle 27 connected to the system image computer 10, an operator may select a scenery from the digital background memory 13 of the CSI system 28 which may be relevent for the training so that this scenery is displayed on the monitor 29. Furthermore, the operator may call up the display of a target (e.g. tank) by means of a panel 30. The targets may be stored for instance in a disk memory library 31 which contains a computer compatible representation of different targets in different attitudes. By means of a further input device 32, it is possible to input, besides the position x, y on the screen and the range E (i.e. size), the pitch, yaw, and roll agles N, G and R of the target in an arbitrary manner.After input of these values they are called up from the system image computer 10 by means of the panel 30. The target described by these values presents now a single cutout from the whole target course, for instance the start of the course. Then the operator may define in the same manner as many points on the target course as he wants and the system image computer 10 may be advised via the panel 30 of the velocity with which the target is moving on the defined course. At the display of the course on the monitor an interpolation takes place betwee all vaues x, y, E, N, G and R which have been inputter point by point. The display on the monitor then results in a continuous movement of the target image which is produced by the computer (CGI = Computer Generated Image). This leads to the impression of a true target motion.

With a standard monocular taking of the background picture for instance with a video camera, any range information with respect to the final digitally stored background image is missed. On the other hand, the target course contains range information and the target changes its size when moving on its course. In order to determine now the range of certain individual objects e.g. bush, forest, etc., in the background image, the following may be done: Figure 4 shows a target Z in the shape of a tank laterally displayed before a forest W. The scale of reproduction of the target Z, i.e. its range may be changed by means of the described input device 32 as long as its size is represented to the operator in a realistic relationship to the individual objects in the background image.It is known that the field of view of the optics for instance is given by an angle of 6 whereas the screen arranged in the field of view of the optics comprises a width of e.g. 107 mm. Then 1 mm in the width corresponds to 6/107 = 1 crossline of the graticule. If then the lateral side of the tank in Figure 4 appears under an angle of 6 crosslines and if, on the other hand, the length of the tank is for instance given with 6 m, then the distance to the tank must be 1000 m. In the shown position of the tank directly in front of the forest it is therefore possible to assign a range of 1000 m to the forest. In the same manner, the ranges of the bushes displayed in front of the forest may be determined.

The basis of the measuring principle described above will be explained with reference to Figure 6. It will be assumed that the screen of the monitor with respect to the operator 0 is arranged in such a way that its image width b5 just fills its viewing field a5 if the viewing optics. Thus an object having size g at a distance e is reproduced on the screen with the size g5 and is viewed from the operator 0 under the angle ag.

From Figure 6 the following relationship may be derived: gel, = tanag for e > > g the following is true: gle =ag (1) Further the following is true: g51b5 = areas (2) From equations (1) and (2) results: e= & a,g/g5 (3) As numerical example, it may be assumed that the screen has a width bs of 125 mm and that this width is filling the field of view of a5 = 6 (corresponds to 105 mrad). If one takes then as a target a tank in a lateral view having a length of g = 6 m and if this tank is reproduced on the screen with a length of g5 = 3.5 mm, then the range e may be computed as follows.

125mm 6m =2041m.

l05mrad 2041 m.

The range evaluated in this manner is assigned to the individual object in the background image adjacent to the tank. If for instance each image point is coded by 16 bits whereby 8 bits (256 levels) are provided for the different grey values, then the remaining 8 bits are available for 256 range levels. With a simulation of a visual field of view at tank sights and with a maximum battle distance of 3000 m, 256 range levels may be provided in the range between 500 and 3000 m, so that with the lowest significant bit a smallest range increment of 10 m is codeable.

As shown in Figure 5, all image points within the contour of an individual object B, Win the background image, have the same range information assigned. For this purpose known methods may be used with which for instance an image point on the contour of an object is unblanked and where by means of an input device (track ball) the unblanked image point on the contour of the individual object is displaced. By means of an appropriate computer program, the same range value may be assigned to all image points within the trace curve.

On the other hand, in a natural environment depressions are to be found in a landscape which may not be seen if the margin of the depression has no remarkable sharpness. A vehicle which is driving in such a depression then intersects an object which may be not observed by an operator. In order to simulate also such a situation it is possible to provide such a depression X for instance in meadow landscape. Also in this case a certain area may be traced round by an unblanked image point and a range information may be assigned to that area and the target then driving into this area may be partly or totally covered.

Claims

1. Apparatus for simulation of a field of view wherein a background image is displayed on a TV monitor and the image of a moveable target is cut-in in that background, and wherein the background and target images are digitally stored and are displayed after conversion into a video signal, characterized in that individual objects in the background image are provided with digital range information and that, image point by image point, the range information with respect to the individual object is compared with a digital range information of the target in order to determine, image point by image point, whether the target is covered by the individual object or is to be displayed in front of that individual object.

2. Apparatus according to Claim 1, characterized in that the range information with an individual object is produced by moving the target into the neighbourhood of the object and scaling the target with respect to the background image.

3. Apparatus according to Claim 2, characterized in that by unblanking of an image point on the contour of an individual object and by tracing of that object with the unblanked image point, the same range information is assigned to all image points within the object.

4. Apparatus according to Claim 3, characterized in that individual areas may be provided randomly in the background image in which areas the target is displayed partly or totally covered by the background.

5. Apparatus according to any previous claim, characterized in that, with respect to different points of the target course, besides the coordinates and a range information additionally pitch, yaw, and roll angles are provided by an operator and that through interpolation by means of a computer a target course with a realistic motion behaviour is produced.

6. Apparatus according to any previous claim, characterized in that each image point of the target and of the background comprises information coded by a plurality of bits with respect to the grey value and to the range.