KR20210023431A - Position tracking system using a plurality of cameras and method for position tracking using the same - Google Patents

Abstract

In a position tracking system using multiple cameras and a position tracking method using the same, the position tracking system capable of improving the convenience of position tracking includes a marker, multiple cameras, and a reference camera. The marker is a target for tracking, and a predetermined marker pattern is formed. The cameras are located at different positions, and each of the cameras includes a front unit facing the marker and a photographing unit fixed to the front unit to photograph the marker. The reference camera includes one pair of first and second reference cameras fixed in position and disposed so as to face the front units of the cameras, and a connection unit connecting the first and second reference cameras.

Description

Location tracking system using multiple cameras and location tracking method using the same {POSITION TRACKING SYSTEM USING A PLURALITY OF CAMERAS AND METHOD FOR POSITION TRACKING USING THE SAME}

The present invention relates to a location tracking system and a location tracking method using the same, and more particularly, in tracking the location of a marker using a plurality of cameras, even if the location of some of the cameras is changed, the initial location is automatically determined. The present invention relates to a location tracking system using a plurality of cameras, which can be calculated and eliminates the use of a separate calibration tool, and a location tracking method using the same.

Techniques for tracking positions of various kinds of objects that are stationary or moving have been developed in various ways, especially with an increase in demand related to monitoring the movement of surgical instruments in a medical field in recent years.

In general, in order to track the location of a moving object, a technique of attaching a traceable marker to the object and tracking it in real time using a camera is applied.

However, in the case of an operation site, there is a limitation in that it is difficult to track using a single camera in a situation where various surgical tools or surgical equipment are arranged, so it is common to use a plurality of cameras to track an object to which a marker is attached. Accordingly, in order to accurately track the location of the marker, it is necessary to acquire information on the initial location of each of the plurality of cameras.

In this case, if the positions of the plurality of cameras are always fixed, it is sufficient to use information on the initial setting positions of each of the plurality of cameras, but the position of each of the cameras changes as the actual marker is moved or the marker changes. can do.

When the positions of each of the cameras are changed as described above, the positions of each of the cameras must be reset. In the conventional case, a separate dedicated calibration tool has been used for such position reset. However, in the case of using such a separate dedicated calibration tool, there are various problems such as an increase in time and cost, as well as a need to stop operations such as surgery for repositioning.

Korean Patent Registration No. 10-0757261

Accordingly, the technical problem of the present invention is conceived in this respect, and an object of the present invention is to track the position of a marker using a plurality of cameras, even if the position of some of the cameras is changed, the initial position automatically changed. To provide a location tracking system using a plurality of cameras that can be calculated, thereby enabling more efficient initial location calculation and improving the convenience of tracking the location of a marker.

In addition, another object of the present invention is to provide a location tracking method using the location tracking system.

A location tracking system according to an embodiment for realizing the object of the present invention described above includes a marker, a plurality of cameras, and a reference camera. The marker becomes an object of tracking, and a predetermined marker pattern is formed. The cameras are positioned at different positions, and each includes a front portion facing the marker and a photographing portion fixed to the front portion to photograph the marker. The reference camera has a fixed position and includes a pair of first and second reference cameras arranged to face front portions of the cameras, and a connection part connecting the first and second reference cameras.

In one embodiment, each of the cameras may further include a plurality of light emitting units arranged on the front surface.

In an embodiment, when calculating the initial position of each of the cameras, the light-emitting units may emit light only to preset light-emitting units to form a unique pattern.

In one embodiment, a unique pattern formed by the light emitting units may be different for each camera.

In an exemplary embodiment, at least three light-emitting units having different spacing distances among the light-emitting units may emit light to form the unique pattern.

In one embodiment, all of the light emitting units may emit light when tracking the position of the marker.

In one embodiment, each of the cameras may further include an identification pattern arranged in a plurality of preset unique patterns on the front surface.

In an embodiment, the identification pattern is an infrared reflection pattern, and the reference camera may identify the infrared reflection pattern.

In an embodiment, the reference camera calculates a relative position of each of the cameras by photographing the front portions of the cameras, and determines an initial position of each of the cameras based on the position of the reference camera and the calculated relative position. Can be calculated.

In a location tracking method according to an embodiment for realizing the object of the present invention, calculating initial positions of the plurality of cameras using the location tracking system, and the marker based on the initial positions of the cameras. And tracking the location of.

In an embodiment, the calculating of the initial position may be performed whenever the position of at least one of the cameras is changed.

In one embodiment, the calculating of the initial position comprises the steps of generating a preset unique pattern for each of the cameras, the reference camera, identifying each of the cameras, and determining the position of the reference camera. It may include calculating a relative position of each of the cameras, and calculating an initial position of each of the cameras based on the position of the reference camera.

In one embodiment, in the step of generating the preset unique pattern, each of the cameras may form a unique pattern by emitting only preset light emitting units among a plurality of light emitting units arranged on the front surface.

In one embodiment, the tracking of the position of the marker comprises: providing light to the marker by emitting light from all of the plurality of light emitting units arranged in the reference camera and the plurality of light emitting units arranged in each of the cameras. , And calculating the position of the marker by each of the reference camera and the cameras.

In an embodiment, in the step of calculating the position of the marker, the reference camera may identify the marker and the cameras based on information on the marker pattern of the marker and calculate the position of the marker.

According to embodiments of the present invention, in tracking a marker using a plurality of cameras, each camera is identified by using a reference camera that is fixed in position and arranged to face the cameras, and By calculating the position, it is possible to derive the position of each camera based on the initial reference position of the reference camera, so that the position of each of the plurality of cameras can be easily derived without using a separate calibration tool for calculating the initial position. can do.

That is, when at least one of the cameras changes position, to calculate the initial position of the changed cameras, the changed position of the cameras is updated only by photographing the cameras through the reference camera without using the calibration tool. Since it can be derived, it is possible to reduce the preparation time for location tracking and improve the user's convenience in the situation of location tracking in which the location of the cameras is frequently changed due to the size of a marker or an obstacle.

In particular, by utilizing a structure in which a plurality of light-emitting parts are arranged on the front part of cameras generally used in a location tracking system, only a part of the light-emitting parts are selectively emit light to form a unique pattern, and such a unique pattern By setting differently for each camera, the reference camera can easily identify each camera and easily derive a relative position between the cameras based on photographing information for a unique pattern.

In contrast, by further forming an identification pattern that forms a separate pattern on the front side of the cameras, the reference camera can easily identify each camera and, based on the shooting information for the unique pattern, each camera It becomes possible to easily derive the relative position between them.

On the other hand, in the location tracking of the marker, since the location information of each camera and the reference camera is derived, if only the relative location information between the marker and the camera that photographs it is derived, the location information of the marker is Since it can be directly derived, it is very easy to track the location of the marker.

In particular, when tracking a marker in an environment such as an operating room, it may be difficult to accurately photograph the marker due to obstacles such as surgical tools, equipment, or surgical personnel, but the cameras are arranged to face the cameras as well as the cameras. Since the reference camera is also capable of photographing the marker to derive the location information of the marker, it is possible to photograph the marker from more various angles, thereby minimizing the influence of interference on the obstacle. .

1 is a schematic diagram showing a location tracking system using a plurality of cameras according to an embodiment of the present invention.
2 is a front view illustrating the camera of FIG. 1.
3A and 3B are front views illustrating examples of light emission patterns for calculating an initial position in the camera of FIG. 2.
4 is a schematic diagram showing a position tracking state of a marker using the cameras of FIG. 1.
5 is a schematic diagram showing a state in which cameras located opposite to the marker in the reference camera are identified in the position tracking of the marker of FIG. 4.
6 is a schematic diagram showing a location tracking system using a plurality of cameras according to another embodiment of the present invention.
7 is a flowchart illustrating a location tracking method using the location tracking system of FIG. 1.
8 is a flowchart illustrating a step of calculating an initial position of a camera in FIG. 7, and FIG. 9 is a flowchart illustrating a step of tracking a position of a marker in FIG. 7.

The present invention will be described in detail in the text, since various modifications can be made and various forms can be obtained. However, this is not intended to limit the present invention to a specific form disclosed, it should be understood to include all changes, equivalents, or substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals have been used for similar elements. Terms such as first and second may be used to describe various elements, but the elements should not be limited by the terms.

In the present application, terms such as "comprise" or "consist of" are intended to designate the presence of features, numbers, steps, actions, elements, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance the possibility of the presence or addition.

Unless otherwise defined, all terms used herein including technical or scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Does not.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

1 is a schematic diagram showing a location tracking system using a plurality of cameras according to an embodiment of the present invention.

Referring to FIG. 1, the position tracking system 10 according to the present embodiment is a system for tracking the position of the marker 500 of FIG. 5 to be described later, and includes a reference camera 100 and a plurality of cameras 200 and 300. , 400).

The reference camera 100 is positioned toward a direction in which all of the plurality of cameras 200, 300, 400 can be viewed, that is, all of the plurality of cameras 200, 300, 400 can be photographed. .

In this case, the position of the reference camera 100 is in a fixed state, and the posture or direction of the reference camera 100 is also in a fixed state.

That is, since the position of the reference camera 100 is fixed, information on the initial position of the reference camera 100, that is, information on the initial coordinate and initial direction of the reference camera 100 is not shown. It is stored in the control unit or the database unit.

The reference camera 100 includes a pair of first and second reference cameras 110 and 120 and a connection unit 130.

The first and second reference cameras 110 and 120 are connected through the connection part 130, and in FIG. 1, the connection part 130 is shown in the shape of a connection frame, but the connection part 130 is The structure of connecting the first and second reference cameras 110 and 120 to each other is not limited.

In this way, since the first and second reference cameras 110 and 120 are relatively connected through the connection unit 130, the reference camera 100 is integrally formed so that its position and posture are initially set positions. And does not change in posture.

That is, the first and second reference cameras 110 and 120 and the connection part 130 may be integrally fixed to one position and posture of defects, and each of the elements is relatively not moved with respect to the other elements. Does not.

Accordingly, if initial position coordinate information of the reference camera 100 is set based on the center of the connection unit 130 as shown, for example, as an XYZ coordinate axis in FIG. 1, the first and Coordinate information for an arbitrary position of each of the second reference cameras 110 and 120 is also set, and the initial position coordinate information set in this way is not changed.

Meanwhile, the first reference camera 110 includes a photographing unit 111, and the second reference camera 120 also includes a photographing unit 121, and accordingly, the first and second reference cameras ( Information on the location and direction of the photographing units 111 and 121 of 110 and 120 is stored in the control unit or the database unit, and is not changed in an initial setting state.

In addition, each of the first and second reference cameras (110, 120) is the same as each of the plurality of cameras (200, 300, 400) to be described later, except that they are connected through the connection unit 130. It may be a camera having a structure and shape.

Thus, although not shown in FIG. 1, each of the first and second reference cameras 110 and 120 includes a plurality of light emitting units arranged on the front side of each of the plurality of cameras to be described later. , 121) may be arranged adjacent to each other.

Further, the first and second reference cameras 110 and 120 are arranged so that a pair of them face the same direction, and may be so-called stereo cameras, so that the plurality of cameras 200, 300, 400 ) It is possible to obtain a stereoscopic image for each.

The plurality of cameras 200, 300, 400 are disposed in a specific space, for example, an operation space, etc. to photograph the marker 500, and in FIG. 1, it is illustrated that three cameras are disposed. The number of cameras is not limited.

In particular, in the case of a specific space such as an operation space, when the marker 500 moves, the marker 500 may be covered by a specific structure of the specific space, for example, a surgical tool, a surgical device, or an operator. , By arranging a plurality of cameras 200, 300, 400 at different locations on the specific space as described above, even if it is difficult to track the marker 500 by any one camera, through another camera Since the marker 500 can be tracked, it is possible to continuously track the marker when the marker 500 is moved.

Meanwhile, as described above, when the plurality of cameras 200, 300, and 400 are arranged at arbitrary positions in the specific space, the reference camera 100 is arranged to face the front portions of the plurality of cameras. Through this, the reference camera 100 may acquire location information of each of the plurality of cameras.

Since each of the plurality of cameras 200, 300, and 400 has the same structure and shape, referring to FIG. 2, the camera 200, or the first camera, as a representative, is more specific with respect to the structure and shape. It will be described in detail.

2 is a front view illustrating the camera of FIG. 1.

That is, referring to FIGS. 1 and 2, the camera 200 includes a body portion 201 on which a front portion 202 is formed, a photographing portion 210, and a light emitting portion 220.

The body portion 201 is formed in various shapes such as a block shape, the front portion 202 is formed on the front surface of the body portion 201, and the front portion 202 is the reference camera ( 100).

The photographing unit 210 is located in the center of the front portion 202, and the photographing unit 210 performs photographing of the marker 500.

The light emitting parts 220 are arranged on the front part 202 at regular intervals around the photographing part 210. In this case, FIG. 2 shows that the light-emitting units 220 are arranged in a rectangular shape along the periphery of the photographing unit 210 in one row, but the number of rows in which the light-emitting units 220 are arranged, or the shape in which the light-emitting units 220 are arranged It is obvious that can be changed in various ways.

Each of the light-emitting units 220 may be, for example, a light source such as an LED, and may be individually driven and individually turned on/off.

Meanwhile, as described above, each of the first and second reference cameras 110 and 120 may also include a light emitting unit in which LED light sources are uniformly arranged on the front surface, similarly to the camera 200.

In this embodiment, the initial position of the reference camera 100 is set, and the position of the reference camera 100 does not change.

However, the positions of the plurality of cameras 200, 300, and 400 may change as the position of the marker 500 changes, and thus, the positions of the cameras are not only the initial positions, but also the positions of the respective cameras. Whenever is changed, information on its location must be obtained.

In particular, in the case of this embodiment, a separate calibration tool for measuring the initial position and the changed position of the cameras is omitted, and the initial position and changed position information of the cameras are obtained using the reference camera 100. It is characterized.

That is, in a state in which initial position information of the reference camera 100 is obtained, the position of each of the plurality of cameras 200, 300, 400 from the reference camera 100, that is, with respect to the reference camera 100 When information on the relative positions of the cameras 200, 300, and 400 is obtained, position information of each of the cameras 200, 300, and 400 can be derived.

In this embodiment, in order to obtain information on the relative position of each of the cameras 200, 300, 400, first, after the reference camera 100 identifies each of the cameras, Acquire location information.

Accordingly, each of the cameras 200, 300, and 400 turns on a part of the light-emitting unit 220 with a respective light-emitting pattern that is distinct from other cameras, so that a corresponding camera can be identified.

That is, in the reference camera 100, based on the pattern information pre-allocated for each of the cameras 200, 300, 400, based on the pattern emitted from each of the cameras, which camera corresponds to First, identify them.

In this way, when the identification of each camera is terminated, in the reference camera 100, a pre-allocated pattern emitted from each of the cameras 200, 300, 400, that is, the light emission in the ON state among the light emitting units Based on the light emitting units, distance information to each of the cameras 200, 300, and 400 is obtained.

In this case, since the reference camera 100 includes first and second reference cameras 110 and 120 which are a pair of stereo cameras, the reference camera ( 100) to an arbitrary camera (ie, 3D coordinate information of xyz) can be obtained.

As described above, when the reference camera 100 identifies each camera and acquires location information to each camera, the initial setting position information of the reference camera 100 and the reference camera 100 Based on the relative position information between the respective cameras, position information of each of the cameras, that is, absolute position information of the reference coordinate system is obtained.

Meanwhile, an example of a light emission pattern of each of the cameras for the reference camera 100 to identify each of the cameras or to obtain relative position information to each of the cameras will be described as follows.

3A and 3B are front views illustrating examples of light emission patterns for calculating an initial position in the camera of FIG. 2.

That is, as shown in FIG. 3A, among the light emitting units 210 of the camera 200, only the first to third light emitting units 221, 222, and 223 are selectively emitted (ON), and the other light emitting units are It can be turned off.

In this case, the distance between the first light emitting part 221 and the second light emitting part 222 is'a', and the distance between the first light emitting part 221 and the third light emitting part 223 is'b'. , The distance between the second light-emitting part 222 and the third light-emitting part 223 may be'c', and in this case, a, b, and c may all be set differently.

As described above, by selectively emitting only three light emitting units having different separation distances, the reference camera 100 can identify the camera 200 and obtain distance information to the camera 200. I can.

That is, the reference camera 100 may acquire a relative coordinate with the camera 200 by recognizing three points having different separation distances.

The reference camera 100 may derive a plane consisting of three points, and obtain information on a posture of a corresponding camera based on the derived plane. In addition, the center coordinate information of the camera may be obtained based on the positions of the three points of light emission, that is, position information of the light emitting units in the camera and the positions of the light emitting units among the light emitting units. Thus, it is possible to obtain relative position information from the reference camera to the camera based on the information on the attitude of the camera and the center coordinate information.

In this case, as shown in FIG. 3B, in the case of different cameras 300, the previously selected light emitting portions 321, 322, and 323 have a separation distance between each of the light emitting portions a', b', respectively. The light emission (ON) may be performed to become ,c'. As such, the different cameras 200 and 300 have different light emitting units in different patterns, so that the reference camera 200 may use different cameras. Can be identified.

Meanwhile, the camera 300 of FIG. 3B also emits three light emitting units, so that the reference camera 100 recognizes three points and obtains relative position information to the camera.

In the above, it has been described that three light-emitting units are emitted and position information is obtained by recognizing three points, but three or more light-emitting units may be emitted. Accordingly, by recognizing three or more points and obtaining location information, , It may be possible to obtain more accurate location information.

As described above, in this embodiment, since position information of each of the cameras 200, 300, and 400 can be obtained using the reference camera 100, the position of each of the cameras is changed. In this case, it is possible to immediately derive the positions of the changed cameras without using a calibration tool every time.

Hereinafter, after deriving the positions of the cameras, a description will be given of tracking the marker 500 using the reference camera 100 and the cameras 200, 300, and 400.

4 is a schematic diagram showing a position tracking state of a marker using the cameras of FIG. 1.

4, since the reference camera 100 is disposed to face the cameras 200, 300, 400, the marker 500 is, as shown, the reference camera 100 and the cameras It is located between (200, 300, 400).

In addition, even when the marker 500 is moved, each of the cameras 200, 300, and 400 is individually moved, so that the marker 500 is moved to the reference camera 100 and the cameras 200. , 300, 400).

In addition, in the present embodiment, the cameras tracking the marker 500, in addition to the cameras 200, 300, 400, the reference camera 100 also performs tracking.

Thus, since the marker 500 can be photographed not only in one direction but also in the other direction to perform location tracking, the identification of the marker 500 is improved, and the marker 500 is identified by interference. You can minimize the situation that does not work.

That is, in the tracking of the marker 500, each of the first and second reference cameras 110 and 120 of the reference camera 100 is the same as each of the plurality of cameras 200, 300, 400 Performs a function. In this case, since the position information of the first and second reference cameras 110 and 120 as well as the position information of the plurality of cameras 200, 300 and 400 are all derived, the marker 500 Location tracking is enabled.

Position tracking of the marker 500 includes a marker pattern 510 imprinted or formed on the surface of the marker 500, and the photographing units 111 and 121 of the reference camera 100 and the cameras 200 It is performed by identifying the photographing units 210, 310, and 410 of 300 and 400.

That is, when at least one of the reference camera 100 and the cameras 200, 300, 400 identifies the marker pattern 510, although not shown, the marker Distance and direction information from the camera that identifies the pattern 510 to the marker pattern 510 can be derived, and by simultaneously using the position information of the camera that has identified the previously stored marker pattern 510, the marker Position information of the pattern 510, that is, position information of the marker 500 (here, the position information is obtained by obtaining coordinate information of the marker 500 with respect to a reference coordinate system.

As described above, by using the reference camera 100 and the cameras 200, 300, 400, it is possible to easily obtain the location information of the moved marker 500.

Meanwhile, in the case of tracking the position of the marker 500 as described above, the plurality of cameras 200, 300 and 400 emit light of all the light emitting units 220, 320, and 420 arranged in each of the cameras. By (ON), infrared reflection is induced with respect to the marker 500.

For example, the marker pattern 510 of the marker 500 is identified by infrared reflection, and all of the light emitting units 220, 320, 420 of the cameras 200, 300, 400 Infrared LED light is provided to the marker pattern 510, and the marker pattern 510 is obtained by using the infrared reflected light from the marker pattern 510.

In this case, the first and second cameras 110 and 120 of the reference camera 100 also emit all of the light emitting units to provide infrared LED light as the marker pattern 510, and the marker pattern 510 The marker pattern 510 may be obtained using infrared reflected light reflected from ).

However, as described above, when tracking the location of the marker 500, all the light emitting units of the cameras 200, 300, and 400 disposed to face the reference camera 100 emit light, and the arrangement At the position of, the reference camera 100 receives light provided from the cameras 200, 300, and 400 at the same time as the marker 500.

Accordingly, when the reference camera 100 identifies a marker, a problem in which it is difficult to identify the marker may occur due to light provided from the cameras. That is, since the reflected light reflected from the marker pattern 510 and the light provided from the cameras are not distinguished from each other, some of the cameras may be mistaken as a marker and an error in deriving the distance to the marker may occur.

Likewise, the cameras 200, 300, and 400 may also generate an identification error for the marker 500 due to the reference camera 100.

FIG. 5 is a schematic diagram showing a state in which cameras located opposite to the marker in the reference camera are identified in the position tracking of the marker of FIG. 4.

5, as described above, as all of the light emitting units 220, 320, 420 arranged on the front portions 202, 302, and 402 of the cameras 200, 300, 400 emit light, the reference camera ( At 100), an error in identification of light reflected from the marker pattern 510 may occur due to the light emitted from the light emitting units 220, 320, 420.

Accordingly, in this embodiment, information on the marker pattern 510 imprinted or formed on the surface of the marker 500, that is, information on the shape and arrangement of the marker pattern 510 is transmitted to the reference camera 100. By providing, it is possible to identify whether the pattern photographed by the reference camera 100 corresponds to the marker pattern 510 or is caused by light emitted from the cameras 200, 300, and 400.

Likewise, the same applies to the case where the cameras 200, 300, 400 cannot identify the marker pattern 510 by the light source emitted from the reference camera 100, and thus the marker pattern 510 is applied to the marker pattern 510. Information about the marker pattern 510, that is, information about the shape and arrangement of the marker pattern 510 is provided to the cameras 200, 300, 400, and the pattern photographed by the cameras 200, 300, 400 is the marker pattern. It is possible to identify whether it corresponds to 510 or is caused by light emitted from the reference camera 100.

Thus, in the present embodiment, through more accurate identification of the marker pattern 510, the accuracy in obtaining the location information of the marker 500 may be further improved.

6 is a schematic diagram showing a location tracking system using a plurality of cameras according to another embodiment of the present invention.

The location tracking system 20 in this embodiment is the location tracking system described with reference to FIGS. 1 to 5, except that an identification pattern having a predetermined pattern is formed on the front side of each of the cameras. Same as 10). Accordingly, the same reference numerals are used for the same components, and redundant descriptions thereof are omitted.

Referring to FIG. 6, in this embodiment, identification patterns 250, 350, 450 are formed on the front surfaces 202, 302, and 402 of the cameras 200, 300, and 400 to have a predetermined pattern. Can be attached or formed.

In this case, the identification patterns 250, 350, and 450 may be a reflection pattern reflected by light emitted from the reference camera 100, that is, an infrared reflection pattern. Accordingly, in order to identify the cameras, the reference camera 100 must provide light to the cameras 200, 300, and 400 through a light emitting unit arranged on the front side.

In addition, the identification patterns 250, 350, and 450 are formed in a three-point pattern, as described above with reference to FIGS. 1 and 2, and the separation distances between the dots must be formed differently.

Furthermore, the identification patterns formed in each of the cameras have different arrangements, and the arrangement information of the identification patterns having different arrangements should be previously stored. Thus, the reference camera 100 may recognize the identification pattern and immediately identify the cameras.

On the other hand, for tracking of the marker 500 by the cameras 200, 300, 400, front portions 202, 302, 402 of the cameras 200, 300, 400 are not shown, The light-emitting units may be arranged, and the marker 500 may be tracked as described above through light emission of the light-emitting units.

In contrast, the identification pattern (250, 350, 450) may be composed of the light emitting unit itself, so that each of the cameras (200, 300, 400) are formed by arranging three light emitting units in an identification pattern on the front side. It could be.

Thus, when the cameras 200, 300, and 400 track the marker 500, only the three light emitting units emit light to perform tracking on the marker 500.

In addition, if the identification patterns 250, 350, and 450 are formed of the light emitting unit itself, when the reference camera 100 identifies the cameras, the identification pattern 250 does not emit additional light. , 350, 450), it is possible to perform identification of the cameras.

Hereinafter, a location tracking method using the location tracking system 10 described with reference to FIGS. 1 to 5 will be sequentially described, and the location tracking method using the location tracking system 20 described with reference to FIG. 6 The case may be applied in the same manner based on the features of the configuration described in FIG. 6.

7 is a flowchart illustrating a location tracking method using the location tracking system of FIG. 1. FIG. 8 is a flowchart illustrating a step of calculating an initial position of a camera in FIG. 7, and FIG. 9 is a flowchart illustrating a step of tracking a position of a marker in FIG. 7.

First, referring to FIG. 7, in the location tracking method, initial positions of the cameras 200, 300, and 400 are calculated (step S10), and location information of the calculated cameras 200, 300 and 400 Wow, based on the previously stored position information of the reference camera 100, the position of the marker 500 is tracked (step S20).

More specifically, referring to FIG. 8, in the initial position calculation step (step S10) of the camera, in a state in which position information on the reference camera 100 is previously stored, all light emitting units of the reference camera 100 are turned off. In this state, each of the cameras 200, 300, and 400 emits light (ON) some of the light emitting units in a unique pattern, that is, a preset pattern (step S11).

In this case, the number of light-emitting units emitted from each of the cameras 200, 300, and 400 may be three having different separation distances, as described above, and the pattern is set differently for each camera.

Thereafter, referring to FIG. 8, the reference camera 100 identifies each of the cameras 200, 300, and 400, and the cameras 200, 300, and 400) Each relative position is calculated (step S12).

The reference camera 100 identifies each of the cameras based on a unique pattern emitted from each of the cameras 200, 300, and 400, and includes the reference camera 100 including a pair of stereo cameras. By using the three-point light emitting unit to obtain information on the plane formed by each camera and the location of the camera, the relative position of each of the cameras 200, 300, 400, that is, each of the reference cameras Relative coordinate information up to the cameras is obtained.

Thereafter, referring to FIG. 8, an initial position of each of the cameras 200, 300, and 400 is calculated based on the position of the reference camera 100 (step S13 ).

Since the initial position of the reference camera 100 is previously stored, the previously stored position information from the reference coordinate system to the reference camera 100 and the cameras 200, 300, 400 from the reference camera 100 Based on the relative position information to each, a position to each of the cameras 200, 300, and 400 from the reference coordinate system may be calculated.

The calculation of this calculation may be performed through a separate control unit or an operation unit.

As described above, after the calculation of the initial position of the camera is finished (step S10), the position of the marker 500 is tracked (step S20).

That is, referring to FIG. 9, in the step of tracking the position of the marker 500 (step S20), each of the cameras 200, 300, and 400 provides light to the marker 500 (step S21).

The cameras 200, 300, and 400 emit light (ON) all the light emitting units to provide light to the marker 500, and in this case, the provided light may be LED infrared light.

In this case, in addition to the cameras 200, 300, and 400, the first and second cameras 110 and 120 of the reference camera 100 may also provide the same LED infrared light to the marker 500. .

Thereafter, referring to FIG. 9, each of the reference camera 100 and the cameras 200, 300, and 400 calculates the position of the marker 500 (step S22).

That is, by confirming that the light provided to the marker 500 is reflected by the marker pattern 510, the reference camera 100 and the cameras 200, 300, 400 are You can calculate the location.

In this case, the reference camera 100 and the cameras 200, 300, 400 acquire position information to the marker 500, that is, position information from the reference camera or cameras to the marker. It is possible to derive the location information from the reference coordinates to the marker based on the location information from the reference coordinates to the reference camera or cameras through a control unit or an operation unit.

According to the embodiments of the present invention as described above, in tracking a marker using a plurality of cameras, each camera is identified by using a reference camera that has a fixed position and is arranged to face the cameras, By calculating the relative position between the cameras, it is possible to derive the positions of each camera based on the initial reference position of the reference camera, so that the position of each of the plurality of cameras can be determined without using a separate calibration tool for calculating the initial position. It can be easily derived.

That is, when at least one of the cameras changes position, to calculate the initial position of the changed cameras, the changed position of the cameras is updated only by photographing the cameras through the reference camera without using the calibration tool. Since it can be derived, it is possible to reduce the preparation time for location tracking and improve the user's convenience in the situation of location tracking in which the location of the cameras is frequently changed due to the size of a marker or an obstacle.

In particular, by utilizing a structure in which a plurality of light-emitting parts are arranged on the front part of cameras generally used in a location tracking system, only a part of the light-emitting parts are selectively emit light to form a unique pattern, and such a unique pattern By setting differently for each camera, the reference camera can easily identify each camera and easily derive a relative position between the cameras based on photographing information for a unique pattern.

In contrast, by further forming an identification pattern that forms a separate pattern on the front side of the cameras, the reference camera can easily identify each camera and, based on the shooting information for the unique pattern, each camera It becomes possible to easily derive the relative position between them.

On the other hand, in the location tracking of the marker, since the location information of each camera and the reference camera is derived, if only the relative location information between the marker and the camera that photographs it is derived, the location information of the marker is Since it can be directly derived, it is very easy to track the location of the marker.

In particular, when tracking a marker in an environment such as an operating room, it may be difficult to accurately photograph the marker due to obstacles such as surgical tools, equipment, or surgical personnel, but the cameras are arranged to face the cameras as well as the cameras. Since the reference camera is also capable of photographing the marker to derive the location information of the marker, it is possible to photograph the marker from more various angles, thereby minimizing the influence of interference on the obstacle. .

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the present invention described in the following claims. You will understand that you can.

10, 20: location tracking system
100: reference camera 110: first reference camera
120: second reference camera 130: connection
200: first camera 300: second camera
400: third camera 202, 302, 402: front part
210, 310, 410: photographing unit 220, 320, 420: light emitting unit
250, 350, 450: identification pattern 500: marker
510: marker pattern

Claims (15)

A marker to be tracked and having a predetermined marker pattern formed thereon;
A plurality of cameras positioned at different positions, each including a front portion facing the marker and a photographing portion fixed to the front portion to photograph the marker; And
Position tracking system including a reference camera that has a fixed position and includes a pair of first and second reference cameras arranged to face the front side of the cameras and a connection unit connecting the first and second reference cameras . The method of claim 1, wherein each of the cameras,
Position tracking system, characterized in that it further comprises a plurality of light emitting units arranged on the front portion. The method of claim 2, wherein the light emitting units,
When calculating the initial position of each of the cameras, the position tracking system, characterized in that to form a unique pattern by emitting only the preset light emitting portions. The method of claim 3,
The position tracking system, characterized in that the unique pattern formed by the light emitting units is different for each camera. The method of claim 3,
A position tracking system, characterized in that at least three of the light-emitting parts, each of which have different spacing distances, emit light to form the unique pattern. The method of claim 2, wherein the light emitting units,
When tracking the position of the marker, the position tracking system, characterized in that the light emission. The method of claim 1, wherein each of the cameras,
Position tracking system, characterized in that it further comprises an identification pattern arranged in a plurality of preset unique patterns on the front portion. The method of claim 7,
The identification pattern is an infrared reflection pattern, and the reference camera identifies the infrared reflection pattern. The method of claim 1, wherein the reference camera,
And calculating a relative position of each of the cameras by photographing front portions of the cameras, and calculating an initial position of each of the cameras based on the position of the reference camera and the calculated relative position. Calculating initial positions of the plurality of cameras using the position tracking system of claim 1; And
And tracking the position of the marker based on the initial positions of the cameras. The method of claim 10, wherein calculating the initial position comprises:
The location tracking method, characterized in that it is performed whenever the location of at least one of the cameras is changed. The method of claim 10, wherein calculating the initial position comprises:
Generating a preset unique pattern for each of the cameras;
Identifying, by the reference camera, each of the cameras, and calculating a relative position of each of the cameras with respect to the position of the reference camera; And
And calculating an initial position of each of the cameras based on the position of the reference camera. The method of claim 12, wherein in the step of generating the preset unique pattern,
Each of the cameras forms a unique pattern by emitting only preset light emitting units among a plurality of light emitting units arranged on the front surface. The method of claim 10, wherein tracking the location of the marker,
Providing light to the marker by emitting light from all of the plurality of light emitting units arranged in the reference camera and the plurality of light emitting units arranged in each of the cameras; And
And calculating the position of the marker by each of the reference camera and the cameras. The method of claim 14, wherein in the step of calculating the position of the marker,
The reference camera, based on the information on the marker pattern of the marker, to identify the marker and the cameras, the position tracking method, characterized in that to calculate the position of the marker.

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