method, computer program and apparatus for … · the present invention relates to motion tracking....

METHOD, COMPUTER PROGRAM AND APPARATUS FOR DETERMINING

MOTION INFORMATION

FIELD OF THE INVENTION

The present invention relates to motion

tracking. More particularly, the present invention

relates to a method, a computer program and an

apparatus for determining motion information of an

object from a video signal.

BACKGROUND OF THE INVENTION

Motion capture is a term that describes the

process of recording motion and translating the motion

onto to a digital model. Presently there are available

different kinds of commercial products which are based

on various technologies, e.g. optical systems and non-

optical systems. Some of the optical systems are based

on a usage of special optical markers the movements of

which are recorded on a video. To reproduce movement

the video is analyzed using various techniques.

Examples of the non-optical systems include e.g.

various kinds of inertial sensors. When using

intertial sensors the measurement information has to

be transmitted to a receiving entity either in a wired

or wireless manner.

The existing motion capture systems have

several drawbacks. Often the systems, e.g. optical

systems are complex, require much processing power and

need special equipment to work. Furthermore, if non-

optical systems are used, there is a need for a

special receiver receiving the transmission from the

wired or wireless transmitter.

Based on the above there is an obvious need

for a solution that would mitigate and/or alleviate

the above drawbacks.

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SUMMARY OF THE INVENTION

According to an aspect there is provided a

method for determining motion information of an object

from a video signal. The method comprises: receiving

the video signal, the video signal comprising a

plurality of frames representing motion; analysing the

video signal to determine at least one identifiable

object in the plurality of frames of the video signal;

and determining motion information of the object

orthogonal to the two dimensional planar motion of the

video signal by tracking changes in optical properties

of the at least one identifiable object in the

plurality of frames of the video signal.

According to another aspect of the invention

there is provided a computer program comprising

program code, which when executed on a processor

implement the method of any of claims 1 – 10.

According to another aspect of the invention

there is provided an apparatus for determining motion

information of an object from a video signal. The

apparatus comprises: a processor; means for receiving

the video signal; and a memory comprising a computer

program, which when executed by the processor is

configured to: receive the video signal, the video

signal comprising a plurality of frames representing

motion; analyse the video signal to determine at least

one identifiable object in the plurality of frames of

the video signal; and determine motion information of

the object orthogonal to the two dimensional planar

motion of the video signal by tracking changes in

optical properties of the at least one identifiable

object in the plurality of frames of the video signal.

According to yet another aspect of the

invention there is provided a system for determining

motion information of an object from a video signal.

The system comprises: a video camera; at least one

identifiable object attachable to a target; an

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apparatus comprising a processor; means for receiving

the video signal; and a memory comprising a computer

program, which when executed by the processor is

configured to: receive the video signal, the video

signal comprising a plurality of frames representing

motion; analyse the video signal to determine at least

one identifiable object in the plurality of frames of

the video signal; and determine motion information of

the object orthogonal to the two dimensional planar

motion of the video signal by tracking changes in

optical properties of the at least one identifiable

object in the plurality of frames of the video signal.

The advantages of the invention relate to

simplicity. With the invention it is possible to track

three-dimensional motion by using only one video

camera. Furthermore, since the motion information is

coded into a video signal, the decoding can be done

regardless of the location.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included

to provide a further understanding of the invention

and constitute a part of this specification,

illustrate embodiments of the invention and together

with the description help to explain the principles of

the invention. In the drawings:

Figure 1 discloses a flow diagram of a method

according to one embodiment of the invention,

Figure 2 discloses an initial arrangement

according to one embodiment of the invention,

Figures 3A and 3B disclose an embodiment for

decoding three-dimentional movement from a video

signal,

Figures 4A and 4B disclose another embodiment

for decoding three-dimentional movement from a video

signal,

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for decoding three-dimentional movement from a video

signal,

Figure 6 discloses an apparatus according to

one embodiment of the invention, and

Figure 7 disclosed a system according to one

embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the

embodiments of the present invention, examples of

which are illustrated in the accompanying drawings.

Figure 1 discloses a block diagram of

illustrating one embodiment of the invention. At step

100, a video signal is received. The video signal

comprises a plurality of frames. The signal itself may

consist any suitable frame rate, e.g. 24fps or 30fps

or higher or even less. Furthermore, the pixel size of

a single frame depends on a camera used to record the

video signal. At step 102 the video signal is analysed

to determine at least one identifiable object in the

plurality of frames of the video signal. The

identifiable object refers e.g. to a particular shape,

colour or optical element which is identifiable from a

frame of the video signal. At step 104 motion

information of the object orthogonal to the two

dimensional planar motion of the video signal is

determined by tracking changes in optical properties

of the at least one identifiable object in the

plurality of frames of the video signal. In general

this means that motion information of the object

orthogonal to the two dimensional planar motion of the

video signal can be determined from a two-dimensional

video signal. This makes possible e.g. to capture and

determine movement information of the object in each

three dimension based on a video signal from a single

camera.

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Figure 2 illustrates an initial arrangement

of the invention at hand. A video camera 24 is

recording movements 20 of at least one object. The

movements happen three-dimensionally, but the video

camera 24 captures only a two-dimensional motion plane

22 of the movements 24. Thus, the objective of the

invention is how to capture three-dimensional

movements from a video signal presenting only a two-

dimensional motion plane.

Figures 3A and 3B disclose an embodiment in

which motion information of an identifiable object 30

orthogonal to the two-dimentiosional planar motion

component of the object 30 is determined by tracking

changes in opticl properties of the objec 30t.

In the embodiment of Figures 3A and 3B, the

two-dimensional motion component of the object 30 is

determined from the video signal by using e.g. one or

more markers (not shown in Figures 3A and 3B). The

marker, e.g. a passive marker is coated e.g. with a

retroreflective material to reflect light back to a

camera. The two-dimensional motion can then be tracked

by tracking the position of the marker in the two-

dimentional planar video signal.

In Figures 3A and 3B represent consecutive

frames of the video signal, and motion information of

the object 30 orthogonal to the two-dimensional planar

motion component is calculated from changes in the

relative size of the at least one identifiable object

30 in the frames. In Figure 3A the object 30 is

represented with a black circle having position

coordinates x1, y1, z1. It is evident to a skilled

person that there might not be any fixed coordinate

system in use. A more important piece of information

is the difference in coordinates (positions) between

two consecutive frames. In Figure 3B the object 30 has

moved (x2, y2, z2) compared to the position in the

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previous frame (Figure 2A). In this embodiment only

the object 30 moves and the camera stays in place.

In Figure 3A the relative size of the object

30 in the video signal has a fist value. In Figure 3B

the relative size of the object 30 is bigger. Since

the camera stays in place, the change in the relative

size of the identifiable object 30 represents movement

of the object to a direction orthogonal to the two-

dimensional planar motion component determined e.g.

from the earlier mentioned marker. In short, the

bigger the object 30 (the black circle in this case)

is in a data frame, the closer it is to the camera.

Furthermore, the accuracy of determining of

motion in the direction orthogonal to the two-

dimensional planar motion component may also depend on

the total pixel size and the frame rate of the camera.

For example, an inexpensive web camera may have a

frame rate of 30 frames per second (fps) and a total

pixel size of 640x480. It is evident that if the

object moves fast, the movement is captured more

accurately with a higher fps value. Furthermore, the

size of a single pixel in a 640x480 web camera is much

bigger than e.g. in a better three megapixel camera

(e.g. 2048x1536 pixels). Thus, the accuracy of the

motion information of the object 30 orthogonal to the

two-dimensional planar motion component is more

accurate when the total pixel size and the frame rate

of the camera increases.

Furthermore, it was mentioned above that a

marker is separate from the light source. In another

embodiment, the marker and the light source comprise a

single element, i.e. the light source act also as a

marker.


of the invention at hand. In the embodiment of Figures

4A and 4B, motion of an object 40 in a direction

orthogonal to the two-dimensional planar motion

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component based on the optical properties of the

object 40.


two-dimensional motion component of the object 40 is

determined from the video signal by using e.g. one or

more markers 42. The marker 42, e.g. a passive marker

is coated e.g. with a retroreflective material to

reflect light back to a camera. The two-dimensional

motion can then be tracked by tracking the position of

the marker 42 in the two-dimentional planar video

signal.


object 40 is a light source. The ligth source is e.g.

a light emitting diode (LED). Depth information, i.e.

the third motion component of the object 40 is

determined from the signals of the light source in the

video signal. The object 40 (light source) is attached

to a target. The target is e.g. a hand, first, foot or

any other target the movement of which is to be

tracked. As said above, the movement of the target is

coded in a predetermined manner into signals of the

light source 40 so that it is possible to determine

the last motion component needed from the video

signal. The coding is based on e.g. a usage of at

least one accelerometer. The accelerometer itself may

be based on any possible and applicable technology.

The measurements of the accelerometer are coded into

light signals so that it is possible to decode the

previously encoded motion information afterwards. The

coding is executed so that both the quantity and

direction can be decoded from the signals of the light

source 40. Furthermore, the intensity of light may

also be used in the coding procedure, e.g. to indicate

whether the motion is away or toward the camera.

In short, a video camera is used to record

movements of a target. The target is e.g. a body part

of a human being, e.g. a fist. The body part is

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equipped with at least one accelerometer which

provides information about the moving body part. An

accelerometer tracks movements of the body part, e.g.

a fist. Measurements of the accelerometer are coded

into a light signal of at least one light source 40 in

a predetermined manner. It is evident that the target

may be equipped with multiple acceletometer in

different locations and thus also multiple light

sources 40 providing coded movement information of the

multiple accelerometers.

Since the video camera is used to record

movements of the target, it also tracks the light

source 40. In other words, the coded light signal of

the light source 40 appears on the video signal. The

video signal is then transmitted to a recipient via a

communication network, e.g. the Internet.

Alternatively, the video may be locally connected to a

receiving processing device. At the receiving end, a

data processing device, e.g. a computer is provided

with a software application which is arranged to

analyse the video signal to track two-dimensional

planar motion component of the object. The two-

dimensional planar motion component is determined e.g.

based on signals provided by the at least one passive

markers or by any other suitable technique. Several

techniques for tracking two-dimensional planar motion

of a target are known in the art, and therefore they

are not described here in more detail. In addition to

the two-dimensional planar motion component, the

software application determines motion in a direction


component from the signals of the light source, the

signals of the light source having been modulated

based on motion of the object, e.g. the fist already

mentioned above. Based on the two-dimensional planar

motion component and the modulated light signals, the

software application is able to determine movements

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three-dimensionally. The decoding algorithm used in

the software application to decode light signals from

the video signal is apparent to a skilled person. In

short, the software application combines the two-

dimensional information and motion information from

the light source into three-dimensional motion

information.

Furthermore, it was mentioned above that a

marker is separate from the light source. In another

embodiment, the marker and the light source comprise a

single element, i.e. the light source act also as a

marker.

A clear advantage of the solution disclosed

in Figures 4A and 4B is that three-dimensional motion

tracking can be achieved with only one camera and that

there are no special requirements for the camera

itself. Of course, it is evident that more accurate

cameras may provide more accurate video signal. A

further advantege is that decoding can be done

practically anywhere without special equipment, only

the software application is needed to decode the video

signal.


of the invention at hand. In the embodiment of Figures

5A and 5B, motion of an object in each three dimension

is determined based on the optical properties of the

object.


object is a set of three light sources: a red light

source 50, a green light source 52 and a blue light

source 54. Each of the light sources comprise e.g. a

light emitting diode (LED). The individual light

sources may be set so close to each other that they

appear as a single point of light to an ourside

observer. Instead of three led light sources it is

possible to use e.g. layered displays (light sources)

where the three RGB components are superimposed.

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The light sources 50, 52, 54 are attached to

a target. The target is e.g. a hand, foot or any other

target the movement of which is to be tracked. The

movement of the target is coded in a predetermined

manner into signals of the light sources 50, 52, 54 so

that it is possible to determine the last motion

component needed from the video signal.

The coding is based on e.g. a usage of at

least one accelerometer. The object may comprise a

built-in three-axis accelerometer for tracking motion.

In another embodiment, the accelerometer is an

external component from the object. The accelerometer

itself may be based on any possible and applicable

technology. The measurements of the accelerometer are

coded into light signals so that it is possible to

decode the previously encoded motion information

afterwards. In this embodiment, each axis (X, Y, Z) is

coded into a corresponding light source. For example,

the X-axis is coded into the red light source 50, the

Y-axis is coded into the green light source 52 and the

Z-axis is coded into the blue light source 54. The

coding is executed so that both the quantity and

direction can be decoded from the signals of the light

sources 50, 52, 54. Furthermore, the intensity of

light may also be used in the coding procedure, e.g.

to indicate whether the motion is away or toward the

camera. In another embodiment, intensities of the

three light sources may be used in the coding

procedure. The coding procedure may then e.g. use the

proportions of the intensities of the light sources in

the coding procedure.

In short, a video camera is used to record

movements of a target. The target is e.g. a body part

of a human being, e.g. a fist. The body part is

equipped with a three-axis accelerometer which

provides information about the moving body part. An

accelerometer tracks movements of the body part, e.g.

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a fist. Measurements of the accelerometer are coded

into light signals of three light sources 50, 52, 54

in a predetermined manner.

Since the video camera is used to record

movements of the target, it also tracks the light

sources 50, 52, 54. In other words, the coded light

signal of the light sources 50, 52, 54 appears on the

video signal. The video signal is then transmitted to

a recipient via a communication network, e.g. the

Internet. Alternatively, the video may be locally

connected to a receiving processing device. At the

receiving end, a data processing device, e.g. a

computer is provided with a software application which

is arranged to analyse the video signal to determine

motion in a first direction from signals of the red

light source, the signals of the red light source

having been modulated based on motion in the first

direction. Furthermore, the software application

determines motion in a second direction from signals

of the green light source, the signals of the green

light source having been modulated based on motion in

the second direction and motion in a third direction

from signals of the blue light source, the signals of

the blue light source having been modulated based on

motion in the third direction.

Based on the decoded three-dimensional motion

components, the software application is able to

determine movements three-dimensionally. The decoding

algorithm used in the software application to decode

light signals from the video signal itsels is apparent

to a skilled person. In short, the software

application decodes all the needed three-dimensional

motion information from the video signal, where the

video signal comprises RGB coded motion information.

A clear advantage of the solution disclosed

in Figures 5A and 5B is that three-dimensional motion

tracking can be achieved with only one camera and that

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there are no special requirements for the camera

itself. Of course, it is evident that more accurate

cameras may provide more accurate video signal. A

further advantege is that decoding can be done

practically anywhere without special equipment, only

the software application is needed to decode the video

signal.

In one embodiment of Figures 5A and 5B,

decoding motion information from the three light

sources is performed a bit differently. Motion is

first determined from signals of a first light source.

The signals of the first light source have previously

been modulated as a function of absolute sum of

acceleration. The second light source acts as static

reference signal. Direction of the motion is then

determined from signals of a third light source. Thus,

the three-dimentional motion is determined based on

the decoded signals from the first, second and third

light sources.

Figure 6 discloses an apparatus 60 according

to one embodiment of the invention. The apparatus 60

comprises a processor 64 to which is connected a

memory 62 and a video signal receiver 64. The video

signal receiver receives the video signal e.g. via a

local connection or via a data interface connection,

e.g. via a local area network interface of the

apparatus. Although Figure 6 discloses only one memory

62 conneted to the processor 64, the apparatus may

also include other memories. The memory 62 comprises a

softare application which is configured to implement

the motion decoding step disclosed in the description

of Figures 3-5.

The apparatus 60 may also include a receiver

configured to receive a radio transmission. The

processor 64 is then configured to determine motion in

a direction orthogonal to the two-dimensional planar

motion component by simultaneously recording motion

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data received by means of the radio transmission from

the object. The information received from the radio

transmission can be used to combine the planar motion

information from the video signal with the motion data

received by the radio transmission and to correct and

reference the motion information sent by the radio

transmission. The receiver may receive the same

information also via a wired interface. In the case

of radio transmission, the earlier disclosed

identifiable object may itself comprise a radio

transmitter tranmitting information provided by the

accelerometer. In another embodiment, the radio

transmitter may be a separate entity from the object.

Figure 7 discloses a system according to one

embodiment of the invention. The system comprises one

or more identifiable objects 70. The objects have been

described in more detail previously in the

description. The objects are a tracked with a video

camera 72. The video camera 70 has a connection to a

processing apparatus 74 decoding motion information

from the video signal. The connection may be wireless

or wired. Furthermore, The decoding process itself is

implemented e.g. with a software application running

in the processing apparatus. The processing apparatus

itself may be any possible device, e.g. a personal

computer, a laptop computer, a hand-held computer, a

mobile terminal, a mobile phone, a gaming console, a

personal digital assistant etc.

The solution disclosed in the invention can

be used e.g. in gaming applications and/or

apparatuses, various sports, computer vision

applications, telerehabilitation etc.

The exemplary embodiments can include, for

example, any suitable servers, workstations, PCs, lap-

top computers, personal digital assistants (PDAs), In-

ternet appliances, handheld devices, cellular tele-

phones, smart phones, wireless devices, other devices,

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and the like, capable of performing the processes of

the exemplary embodiments. The devices and subsystems

of the exemplary embodiments can communicate with each

other using any suitable protocol and can be imple-

mented using one or more programmed computer systems

or devices.

One or more interface mechanisms can be used

with the exemplary embodiments, including, for exam-

ple, Internet access, telecommunications in any suit-

able form (e.g., voice, modem, and the like), wireless

communications media, and the like. For example, em-

ployed communications networks or links can include

one or more wireless communications networks, cellular

communications networks, 3G communications networks,

Public Switched Telephone Network (PSTNs), Packet Data

Networks (PDNs), the Internet, intranets, a combina-

tion thereof, and the like.

It is to be understood that the exemplary em-

bodiments are for exemplary purposes, as many varia-

tions of the specific hardware used to implement the

exemplary embodiments are possible, as will be appre-

ciated by those skilled in the hardware and/or soft-

ware art(s). For example, the functionality of one or

more of the components of the exemplary embodiments

can be implemented via one or more hardware and/or

software devices.

The exemplary embodiments can store informa-

tion relating to various processes described herein.

This information can be stored in one or more memo-

ries, such as a hard disk, optical disk, magneto-

optical disk, RAM, and the like. One or more databases

can store the information used to implement the exem-

plary embodiments of the present inventions. The data-

bases can be organized using data structures (e.g.,

records, tables, arrays, fields, graphs, trees, lists,

and the like) included in one or more memories or sto-

rage devices listed herein. The processes described

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with respect to the exemplary embodiments can include

appropriate data structures for storing data collected

and/or generated by the processes of the devices and

subsystems of the exemplary embodiments in one or more

databases.

All or a portion of the exemplary embodiments

can be conveniently implemented using one or more gen-

eral purpose processors, microprocessors, digital sig-

nal processors, micro-controllers, and the like, pro-

grammed according to the teachings of the exemplary

embodiments of the present inventions, as will be ap-

preciated by those skilled in the computer and/or

software art(s). Appropriate software can be readily

prepared by programmers of ordinary skill based on the

teachings of the exemplary embodiments, as will be ap-

preciated by those skilled in the software art. In ad-

dition, the exemplary embodiments can be implemented

by the preparation of application-specific integrated

circuits or by interconnecting an appropriate network

of conventional component circuits, as will be appre-

ciated by those skilled in the electrical art(s).

Thus, the exemplary embodiments are not limited to any

specific combination of hardware and/or software.

Stored on any one or on a combination of com-

puter readable media, the exemplary embodiments of the

present inventions can include software for control-

ling the components of the exemplary embodiments, for

driving the components of the exemplary embodiments,

for enabling the components of the exemplary embodi-

ments to interact with a human user, and the like.

Such software can include, but is not limited to, de-

vice drivers, firmware, operating systems, development

tools, applications software, and the like. Such com-

puter readable media further can include the computer

program product of an embodiment of the present inven-

tions for performing all or a portion (if processing

is distributed) of the processing performed in imple-

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menting the inventions. Computer code devices of the

exemplary embodiments of the present inventions can

include any suitable interpretable or executable code

mechanism, including but not limited to scripts, in-

terpretable programs, dynamic link libraries (DLLs),

Java classes and applets, complete executable pro-

grams, Common Object Request Broker Architecture

(CORBA) objects, and the like. Moreover, parts of the

processing of the exemplary embodiments of the present

inventions can be distributed for better performance,

reliability, cost, and the like.

As stated above, the components of the exem-

plary embodiments can include computer readable medium

or memories for holding instructions programmed ac-

cording to the teachings of the present inventions and

for holding data structures, tables, records, and/or

other data described herein. Computer readable medium

can include any suitable medium that participates in

providing instructions to a processor for execution.

Such a medium can take many forms, including but not

limited to, non-volatile media, volatile media, trans-

mission media, and the like. Non-volatile media can

include, for example, optical or magnetic disks, mag-

neto-optical disks, and the like. Volatile media can

include dynamic memories, and the like. Transmission

media can include coaxial cables, copper wire, fiber

optics, and the like. Transmission media also can take

the form of acoustic, optical, electromagnetic waves,

and the like, such as those generated during radio

frequency (RF) communications, infrared (IR) data com-

munications, and the like. Common forms of computer-

readable media can include, for example, a floppy

disk, a flexible disk, hard disk, magnetic tape, any

other suitable magnetic medium, a CD-ROM, CDR, CD-RW,

DVD, DVD-ROM, DVD±RW, DVD±R, any other suitable opti-

cal medium, punch cards, paper tape, optical mark

sheets, any other suitable physical medium with pat-

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terns of holes or other optically recognizable indi-

cia, a RAM, a PROM, an EPROM, a FLASH-EPROM, any other

suitable memory chip or cartridge, a carrier wave or

any other suitable medium from which a computer can

read.

While the present inventions have been de-

scribed in connection with a number of exemplary em-

bodiments, and implementations, the present inventions

are not so limited, but rather cover various modifica-

tions, and equivalent arrangements, which fall within

the purview of prospective claims.

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CLAIMS:

1. A method for determining motion information

of an object from a video signal, the method

comprising:

receiving the video signal, the video signal

comprising a plurality of frames representing

motion;

analysing the video signal to determine at least one

identifiable object in the plurality of frames of

the video signal; and

determining motion information of the object

orthogonal to the two dimensional planar motion of

the video signal by tracking changes in optical

properties of the at least one identifiable object

in the plurality of frames of the video signal.

2. The method according to claim 1, further

comprising:

analysing the video signal to tracktwo-dimensional

planar motion component of the object,

and wherein the determining comprises:

determining relative size of the at least one

identifiable object in the frames of the video

signal; and

calculating motion information of the object


component from the changes in the relative size of

the at least one identifiable object in the frames

of the video signal.

3. The method according to claim 1, wherein the

at least one identifiable object comprises at least

one light source.


determining comprises:

analysing the video signal to track two-dimensional

planar motion component of the object,

wherein the identifiable object is a light source

and the determining comprises:

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determining motion in a direction orthogonal to the

two-dimensional planar motion component from

signals of the light source, the signals of the

light source having been modulated based on motion

of the object.


at least one identifiable object comprises a red light

source, a green light source and a blue light source,


determining motion in a first direction from signals

of the red light source, the signals of the red


of the object in the first direction;

determining motion in a second direction from

signals of the green light source, the signals of

the green light source having been modulated based

on motion of the object in the second direction;

and

determining motion in a third direction from signals

of the blue light source, the signals of the blue


of the object in the third direction.

6. The method according to any of claims 1 - 5,

wherein the at least one identifiable object comprises

three light sources, and wherein the determining

comprises:

determining motion from signals of a first light

source, the signals of the first light source

having been modulated as a function of absolute

sum of acceleration;

determining a static reference signal from signals

of a second light source;

determining direction of the motion from signals of

a third light source; and

determining the three-dimentional motion based on

the decoded signals from the first, second and

third light sources.

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further comprising:


two-dimensional planar motion component by

simultaneously recording motion data received by

means of radio transmission from the object.


comprising:

combining the planar motion information from the

video signal with the motion data received by the

radio transmission, and

correcting and referencing the motion information

sent by the radio transmission.


further comprising:




means of wire transmission from the tracked

object.


comprising:

combining the planar motion information from the

video signal with the motion data received by the

wire transmission, and

correcting and referencing the motion information

sent by the wire transmission.

11. A computer program comprising program code,

which when executed on a processor implement the

method of any of claims 1 – 10.

12. The computer program according to claim 8,

wherein the computer program is embodied on a

computer-readable medium.

13. An apparatus for determining motion

information of an object from a video signal, the

apparatus comprising:

a processor;

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means for receiving the video signal; and

a memory comprising a computer program, which when

executed by the processor is configured to:

receive the video signal, the video signal


motion;

analyse the video signal to determine at least one



determine motion information of the object





14. The apparatus according to claim 13, wherein

the processor is configured to:

analyse the video signal to tracktwo-dimensional

planar motion component of the object;

determine relative size of the at least one

identifiable object in the frames of the video

signal;

calculate motion information of the object


component from the changes in the relative size of

the at least one identifiable object in the frames

of the video signal.


the at least one identifiable object comprises at

least one light source.



analyse the video signal to track two-dimensional

planar motion component of the object; and

determine motion in a direction orthogonal to the

two-dimensional planar motion component from

signals of the light source, the signals of the

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of the object;

wherein the identifiable object is a light source



the at least one identifiable object comprises a red

light source, a green light source and a blue light

source, and wherein the processor is configured to:

determine motion in a first direction from signals

of the red light source, the signals of the red


of the object in the first direction;

determine motion in a second direction from signals

of the green light source, the signals of the

green light source having been modulated based on

motion of the object in the second direction; and

determine motion in a third direction from signals

of the blue light source, the signals of the blue


of the object in the third direction.

18. The apparatus according to claim 13 - 17,

wherein the at least one identifiable object comprises

three light sources, and wherein the processor is

configured to:

determine motion from signals of a first light

source, the signals of the first light source

having been modulated as a function of absolute

sum of acceleration;

determine a static reference signal from signals of

a second light source;

determine direction of the motion from signals of a

third light source; and

determine the three-dimentional motion based on the

decoded signals from the first, second and third

light sources.

19. The apparatus according to any of claims 13 -

18, further comprising:

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a receiver configured to receive a radio

transmission; wherein the processor is configured

to:




means of the radio transmission from the object.



combine the planar motion information from the video

signal with the motion data received by the radio

transmission; and

correct and reference the motion information sent by

the radio transmission.

21. The apparatus according to any of claims 13 -

18, further comprising:

a receiver configured to receive a wire

transmission;wherein the processor is configured

to:




means of wire transmission from the tracked

object.



combine the planar motion information from the video

signal with the motion data received by the wire

transmission; and

correct and reference the motion information sent by

the wire transmission.

23. A system for determining motion information

of an object from a video signal, the system

comprising:

a video camera;

at least one identifiable object attachable to a

target;

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an apparatus comprising a processor; means for

receiving the video signal; and a memory

comprising a computer program, which when executed

by the processor is configured to:

receive the video signal, the video signal


motion;

analyse the video signal to determine at least one



determine motion information of the object





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ABSTRACT

The invention provides a method

for determining motion information of an

object from a video signal. The method

comprises: receiving the video signal,

the video signal comprising a plurality

of frames representing motion; analysing

the video signal to determine at least

one identifiable object in the plurality

of frames of the video signal; and

determining motion information of the

object orthogonal to the two dimensional

planar motion of the video signal by

tracking changes in optical properties

of the at least one identifiable object

in the plurality of frames of the video

signal.

(FIG. 1)

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V I D E O S I G N A L

R E C E I V I N G T H E V I D E O S I G N A L , T H E V I D E OS I G N A L C O M P R I S I N G A P L U R A L I T Y O F F R A M E S

A N A L Y S I N G T H E V I D E O S I G N A L T O D E T E R M I N E A T L E A S T O N E I D E N T I F I A B L E O B J E C T

D E T E R M I N I N G M O T I O N I N F O R M A T I O N O F T H E O B J E C T O R T H O G O N A L T O T H E T W O D I M E N S I O N A LP L A N A R M O T I O N O F T H E V I D E O S I G N A L B Y T R A C K I N G C H A N G E S I N O P T I C A L P R O P E R T I E S O FT H E A T L E A S T O N E I D E N T I F I A B L E O B J E C T

1 0 0

1 0 2

1 0 4

F I G . 1

F I G . 2

2 0

2 2

2 4

F I G . 3 A

x , y , z1 1 1

F I G . 3 B

x , y , z2 2 2

3 0

3 0

F I G . 4 A

x , y1 1

F I G . 4 B

z 1

x , y2 2

z 2

4 04 2

4 04 2

F I G . 5 A

x , y1 1

F I G . 5 B

RBG

, z 1

x , y2 2

RBG

, z 2

5 0

5 2 5 4

5 0

5 2 5 4

V I D E OS I G N A LR E C E I V E R

P R O C E S S O R

M E M O R Y 6 2

6 4

6 6

6 0

F I G . 6

P R O C E S S I N GA P P A R A T U S

V I D E OC A M E R A

I D E N T I F I A B L EO B J E C T ( S )

7 0 7 2

7 4

F I G . 7

method, computer program and apparatus for … · the present invention relates to motion tracking....

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