GB2283144A

GB2283144A - Simulated projectile vision

Info

Publication number: GB2283144A
Application number: GB9320995A
Authority: GB
Inventors: William Alexander Courtney
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-10-12
Filing date: 1993-10-12
Publication date: 1995-04-26
Anticipated expiration: 2013-10-12
Also published as: GB9320995D0; GB2283144B

Abstract

In order to improve television coverage of sports which involve the flight of a projectile over long distances, such as golf or archery, a simulated view of the projectile's landing zone, as seen from the projectile, is produced in real time. Microwave radars or sonars 3, 4, 5 measure the distance to projectile 2 at two instants. From these the trajectory 1 of projectile 2 may be calculated, ignoring wind, spin and air resistance, and hence the estimated landing zone may be determined. This is then combined with either a real-time image produced from a camera located external to the projectile, or with a map or pre-recorded image of the landscape, to provide the simulated view. Thus the viewer will be shown a dramatic view of the game. <IMAGE>

Description

Simulated Projectile Vision This invention is a method and apparatus for producing real time animated images relating to sports events, for analytical and entertainment purposes.

The images relate to long distance movement of projectiles, for example golf balls, cricket balls or archers arrows. The invention may be used to generate images relating to any projectile which is only subject to external natural forces after being launched.

The invention involves apparatus which collects real time data relating to the trajectory of a projectile and then computes and displays an image of the anticipated landing zone.

The displayed image is a reconstructed selection of stored data relating to a representation of a surface which includes all likely landing points for the projectile.

Golf is an example of a sport which attracts considerable media interest but television viewers are denied the most dramatic view of the game, that seen by a hypothetical camera placed inside the golf ball. The method and apparatus to be described produce a simulation of this hypothetical image.

A multiplicity of radar antennae transmit and later detect microwave signals which are reflected by the golf ball. Triangulation techniques are then used to compute successive positions of the golf ball. The current displayed image is determined by combining a real time computation of the predicted landing point of the golf ball and a computation of the size and shape of the area of the landing zone which would be seen by a hypothetical camera placed inside the golf ball.

The image is updated at regular intervals in order to give the illusion of camera movement.

The formulae used to calculate the trajectory of the projectile can be those commonly used for calculations concerning the parabolic motion of a particle moving in a uniform gravitational field.

In reality factors such as projectile spin, wind and thermal currents will affect the shape of the true trajectory and must be allowed for in determining the actual landing point.

However by ignoring these complications and producing a visual display which is based on particle movement in still, non viscous air the viewer is offered a more dramatic, simulated golf ball view. This is a real time view which alters throughout the flight, as the data is up-dated. It captures the sensation of the wind etc which are affecting the flight of the projectile after it has left the tee.

The invention will be illustrated by reference to a specific application.

Figure 1 shows the still air trajectory, 1 of a golf ball, 2 which has been teed off towards the green. Three or more projectile detecting and ranging devices, 3, 4 and 5, are placed on or near the fairway and are used to detect the position in space of the golf ball, using the principles of triangulation.

If the position in space of the golf ball is determined at two instances of time early in the flight and the time interval between the instances is known then the still-air particle trajectory can be computed.

The detectors emit electromagnetic or acoustic radiation of a sufficiently short wavelength that they can detect reflections off the golf ball.

Preferably the detectors are microwave transmittinglreceiving antennae similar to those used for existing ranging radar systems. Radar ranging systems involving pulse return time and phase measurement are described in the prior art. Both are suitable for the current invention with pulse return time systems offering adequate prediction accuracy for entertainment purposes and phase measurement systems yielding high quality data for stroke playing analysis.

Each antenna is preferably tuned to transmit and detect a different frequency in order to eliminate ambiguity between the detected signals.

The number of antennae used and their height above ground are variables. The essential requirement is that at least three antennae are able to transmit and receive reflected signals from from the golf ball for any reasonably expected position in the air space in the vicinity of the fairway.

The positions of the antennae relative to the teeing off point and the hole may be established using standard surveying techniques, including the use of reflected radar signals from retro reflectors temporarily placed at the positions of the tee and hole prior to commencement of play.

The antennae are connected to the central data processing computer by means of cables, radio links or other known means for real time data transfer.

If information concerning the teeing off point is included in the calculation and the teeing off time is known by virtue of having a transmitting sensor in the tee then the particle trajectory can be computed at a very early stage in the flight. A number of sensors capable of registering the removal of the golf ball from the tee are known. These include pressure sensors, optical sensors and sensors based on change of electrical capacitance.

In figure 1, 6 is a straight line from the current position of the golf ball to the computed landing point. The length of this line is d. The line is inclined at an angle 8 to the horizontal. The position of the landing point, the length and direction of d and 0 can all be calculated by those with a knowledge the science of the motion of projectiles. is the assumed solid angle of view of the fictional camera mounted inside the golf ball. The shaded area 7, having area A' is the area around the landing point that can be seen for the given value of . The size and shape of this shaded area can be calculated from a knowledge of , û and d.

However, it can be seen by inspection of the diagram that at low angles of ü the area viewed takes the shape of an ellipse with the ratio of the major to minor axes of the ellipse being considerably greater than 1.0. The practical effect of this is that a television viewer will see a highly foreshortened and not very informative view of the landing zone.

The output display is a simulation dependent on a selection and manipulation of digital data.

This means that for area calculation purposes fictional, controllable values of 0 and (10/cit may be used. A method and apparatus for manipulating 0 and cO/cit is an optional feature of this invention.

The simplest embodiment of the invention ignores the foreshortening effect and produces an image for the viewer such as would be seen by a hypothetical camera at a distance d from the predicted landing point but vertically above the landing point. In this case the hypothetical camera sees a circular area of horizontal ground having area A.

Figure 2 shows a view of the landscape in the region between the tee and the green.

A representation of this landscape is stored as compressed digital data in a computer memory.

The representation may for example be a map, an aero photograph, an electronically recorded image of the landscape or be based on a real time image of the landscape, taken using a camera held high above the fairway. The stored data may be processed by being subjected to a slope shading technique in order to give an apparent three dimensional effect. The direction of shading may vary according to the time of day in order to replicate the direction of shading which would be produced by direct sun light, in order to enhance authenticity. Those with a knowledge of electronic image storage and enhancement techniques will be able to process landscape representational information originating in a number of formats into the required form of compressed digital data.

In figure 2, 1 is the fairway, 2 the green and 3 the tee. 4, 5 and 6 are the minimum number of antennae needed to give a unique set of coordinates in three dimensional space describing the successive positions of the golf ball.

4, 5 and 6 are positioned so that straight lines drawn between them and from them to the current position of the golf ball define the edges of a Tetrahedron.

x', y' are the horizontal cartesian coordinates of the calculated prediction for the landing point, 7 of the ball, measured from the tee. The circular area, 8 is the computed field of view of the hypothetical camera in the golf ball, with no allowance for foreshortening, at the current instant of time. The computed field of view decreases in area and increases in magnification during the flight, providing the sensation of movement.

A value for the length d defined above and the position x', y' determined by computation enables the area of the golf course that would be seen by the hypothetical camera to be identified and then displayed for viewing by an audience.

The televised image is preferably rectangular in shape, with the coordinates of the centre of the rectangle being x', y' and the corners of the rectangle being points on the circumference of a circle with area A If the spatial coordinates of the position of the golf ball at a given instant of time are determined as x1,y1,z1 and at a known time interval, bt later are determined as x2,y2,z2 then a prediction of the landing point coordinates x', y' can be made using standard ballistics formulae.

A pair of cross wires or other markers can be simulated on the display to indicate the computed landing point If there is a significant variation in vertical height between the tee and the green this can be allowed for in the landing point prediction by including prior information concerning the landscape in the calculation.

For example, figure 3a shows a vertical profile of a hilly landscape, 1 directly below the trajectory, 2.

Commonly, major golf courses have their relief shown on maps using contour lines.

Figure 3b shows the relief approximated to horizontal terraces with each terrace representing one contour interval. This relief interpretation can be expressed as a series of straight line equations. The predicted landing point can then be calculated by determining the point in space of the intersection of the trajectory equation with the landscape equations. Allowance for trees and other obstacles can be made in a simiiar manner.

If spin, wind or other factors cause on-going deviation from the previously predicted landing point this shows up as a movement of the marker relative to the background image of the green or fairway. This dynamic change adds visual impact and interest to the display seen by the television viewer.

It is essential that data concerning the projectile of interest is distinguishable from other airborne objects such as birds or helicopters. An number of methods of doing this are available. These include: Confining the solid angle of "vision" of the antennae to the region of space of interest.

2 Credible position checking: If the first calculation on the predicted shape of the trajectory has been made and is based on data from the teeing off point and one set of radar data then the position of the golf ball at the tirhe of collection of the second set of data can be predicted. If the the second set of data differs markedly from the prediction then the projectile is not (even to a first approximation) travelling in a parabolic path and the data can be discarded as invalid.

3 Signal strength checking: The golf ball has radar reflecting properties which clearly distinguish it at a given distance from the above spurious signal generators. A strength of signal measurement weighted for distance using the inverse square law can be made and reflected signals which fall outside an experimentally determined tolerance range can be ignored.

4 One or both of the above checking methods may be supplemented by including one or more further sets of radar data using hand held antennae. Suitable antennae only have a small solid angle of vision, allowing them to demarc a small solid angle of space. The extra data may be additive or subtractive. Additive data is obtained by using the hand held antennae to track the projectile after launching, subtractive data is obtained by pointing the hand held antennae at visible spurious radar reflectors.

Figure 4 is a schematic diagram summarising the key features of one embodiment of the apparatus and method which constitute this invention.

Launch Point Sensor: The launch point sensor sends a system start up signal to the radar antennae which then send out a regular sequence of ranging signals. The valid trajectory checking unit holds prior information concerning the coordinates of the launch point sensor.

Fixed Antennae: A minimum of three antennae transmit ranging signals and send reflected signal data from potentially valid projectiles to the projectile coordinate calculating unit and the signal intensity check unit.

Movable Subtractive Data Radar Antennae: These are operator controlled narrow beam ranging antennae pointed towards visually identified spurious radar reflectors which the operator judges have the potential to confuse the projectile ranging system. They send ranging signals relating to spurious reflectors to the valid data check unit.

Movable Additive Data Radar Antennae: These are operator controlled narrow beam ranging antennae pointed towards valid reflectors. They send confirming signals relating to the direction andlor range of a visually identified valid projectile to the valid data check unit.

Projectile Coordinate Calculating Unit: This processes positioning data from the fixed antennae and produces three dimensional coordinates for possible projectiles.

Valid Data Check Unit: This is an electronic gate which allows transmission of data to the next processing stage provided that the coordinates of the possible projectile are in agreement with the ranging and directional data from the additive data radar antennae but in disagreement with the ranging and direction data received from the subtractive data radar antennae.

Signal Intensity Check Unit: This is an electronic gate which allows transmission of data to the next processing stage provided that the intensity of the signal, corrected for distance from the receiving antenna is within allowed limits.

Valid Trajectory Check Unit: This takes two successive sets of coordinates from a potential projectile and predicts the position of the next set of coordinates using standard ballistics formulae. If the difference between the measured third set of coordinates and the predicted third set is less than a pre set amount (the error margin allows for projectile spin, drag, wind etc) then the trajectory information is allowed to pass to the end point prediction unit.

End Point Prediction Unit: This unit uses projectile trajectory information and combines it with landscape relief data in order to make a prediction of the projectile landing point.

Display Area Calculator: This combines data concerning the coordinates of the currently predicted landing point with a value for the distance from the current position of the projectile to the currently predicted landing point in order to identify the selection of data to be read from the landscape representation store. It takes into account operator chosen perspective and foreshortening requirements.

Reconstruction Processor: This reconstructs the selected digital data from the landscape representation data store in order to create a viewable image of the predicted landing zone.

Output: The output data may be used in a number of ways including real time television transmission, storage on video tape, temporary storage followed by television transmission at a slow frame rate etc.

Claims

1 A method and apparatus for simulating the view of the anticipated landing zone seen by a projectile based on a prediction of the end point of the trajectory combined with a related selection from an image of the possible landing zones produced by a camera or other image producing and recording device which is external to the projectile.

2 As for claim 1 but specifically including a digital processing apparatus and method for performing the necessary computations and selections.

3 A system for simulating the view of the anticipated landing zone seen by a projectile based on a prediction of the end point of the trajectory combined with a related selection from a plan or constructed image of the possible landing zones.

4 As for claim 1 or 2 but with the final image being a real time image, selected from a currently accurate image of the possible landing zones.

5 As for claim 1 or 2 but with the inclusion of an apparatus and method which allows displayed data to be a reconstructed selection from stored, compressed digital data relating to a range of potential images.

6 As for claim 3 but with the apparatus and method also allowing shading techniques to be applied to the displayed data in order to produce a three dimensional effect.

7 As for claim 4 but with the apparatus and method also allowing the direction of shading to be varied in order to give directionally correct shading for the direction of the sun at the time of day of the flight of the projectile.

8 As for the above claims but specifically including a plurality of electromagnetic or acoustic sensors which are able to detect the position in space of the projectile at successive, known intervals of time.

9 As for the above claims but specifically including a plurality of electromagnetic or acoustic sensors which are able to detect the velocity of the projectile at successive, known intervals of time.

10 As for the above claims but specifically including a projectile current position determining apparatus which is, at least, partly based on a pulse return time measuring radar system.

11 As for the above claims but including an error checking system which includes one or more radar antennae which are capable of being manoeuvered during the flight time of the projectile in order to identify unwanted radar reflecting bodies.

1 2 As for the above claims but including apparatus which monitors the intensity of the reflected radar signal and after allowing for the distance between the antennae and the reflecting body, rejects as spurious any signals which do not, to a pre-determined degree of approximation agree with the expected signal intensity.

1 3 A method and apparatus substantially as described or substantially as illustrated in the present application which is used for simulating the image or images that would be seen by a television camera or other imaging device placed inside a moving projectile moving under toe influence of a known force field, such as the force field produced by gravity.

11 As for the above claims but specifically including a projectile current position determining apparatus which is, at least, partly based on a phase measurement radar system.

1 2 As for the above claims but including one or more projectiles which have been coated with radar reflecting material in order to help differentiate the projectiles from spurious reflected radar signals.

1 3 As for any of the above claims but including a sensor at the beginning of the flight path which is able to transmit signals relating to the time andlor position of the beginning of the flight.

1 4 As for the above claims but for a set of apparatus which includes retro reflectors for determining the relationship in space between the antennae, the launch point of the projectile and other points of interest in space such as the relevant hole of a golf course.

1 5 As for the above claims but including a means for computing the predicted position of the projectile at successive intervals of time, comparing these predictions with actual position measurements and then rejecting as spurious any actual position point data which do not agree, to a pre-determined degree of approximation, with the theoretical model.

16 As for the above claims but including one or more radar antennae which are capable of being manoeuvered during the flight time of the projectile in order to provide additional position determining data during the flight of the projectile.

1 7 As for the above claims but including an error checking system which includes one or more radar antennae which are capable of being manoeuvered during the flight time of the projectile in order to identify unwanted radar reflecting bodies.

1 8 As for the above claims but including apparatus which monitors the intensity of the reflected radar signal and after allowing for the distance between the antennae and the reflecting body, rejects as spurious any signals which do not, to a pre-determined degree of approximation agree with the expected signal intensity.

1 9 As for the above claims but for which the projectile is a golf ball and the anticipated landing zones are areas within a golf course of current interest.

Amendments to the claims have been filed as follows 1 A method and apparatus for simulating the view of the anticipated landing zone seen by a projectile based on a prediction of the end point of the trajectory combined with a related selection from an image of the possible landing zones produced by a camera or other image producing and recording device which is external to the projectile and with the inclusion of an apparatus and method which allows displayed data to be a reconstructed selection from stored, compressed digital data relating to a range of potential images.

2 As for claim 7 but with the apparatus and method also allowing shading techniques to be applied to the displayed data in order to produce a three dimensional effect.

3 As for claim 2 but with the apparatus and method also allowing the direction of shading to be varied in order to give directionally correct shading for the direction of the sun at the time of day of the flight of the projectile.

4 As for the above clairns but specifically including a plurality of electromagnetic or acoustic sensors which are able to detect the velocity of the projectile at successive, known intervals of time.

5 As for the above claims but specifically including a projectile current position determining apparatus which is, at least, partly based on a pulse return time measuring radar system.

6 As for the above claims but specifically including a projectile current position determining apparatus which is, at least, partly based on a phase measurement radar system.

7 As for the above claims but including one or more projectiles which have been coated with radar reflecting material in order to help differentiate the projectiles from spurious reflected radar signals.

8 As for the above claims but for a set of apparatus which includes retro reflectors for determining the relationship in space between the antennae, the launch point of the projectile and other points of interest in space such as the relevant hole of a golf course.

9 As for the above claims but including a means for computing the predicted position of the projectile at successive intervals of time, comparing these predictions with actual position measurements and then rejecting as spurious any actual position point data which do not agree, to a pre-determined degree of approximation, with the theoretical model.

10 As for the above claims but including one or more radar antennae which are capable of being manoeuvered during the flight time of the projectile in order to provide additional position determining data during the flight of the projectile.