JP2007187524A - Magnetic mapping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire in a short time, magnetic data necessary for using HMT in a magnetic system. <P>SOLUTION: A device includes a magnetic source 2; a support 16; a magnetometric sensor 3 mounted on the support, for measuring magnetic data in a magnetic field; a group 18 of at least three markers mounted on the outer surface of the support, whose positions to the magnetometric sensor are fixed; a pair of cameras 12, 14 for performing simultaneous stereoscopic view of the three markers; a magnetometric sensor position calculation part 21 for determining each position coordinate of the three markers based on each position on an image of the three markers reflected simultaneously on each image photographed by the pair of cameras, and calculating the position coordinate of the magnetometric sensor based on each determined position coordinate of the three markers; and a magnetic mapping part 22 for accumulating magnetic mapping data acquired by correlating the position coordinate with magnetic data based on the calculated position coordinate of the magnetometric sensor and the magnetic data measured in photographing the camera image. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a magnetic mapping apparatus for measuring a magnetic distribution in a space using a magnetic head motion tracker (hereinafter referred to as HMT).
This apparatus, for example, generates an alternating magnetic field in a space, and based on magnetic data detected by a magnetic sensor attached to a head mounted display (head mounted display (HMD)), the head mounted display It is used in connection with a magnetic HMT that measures the orientation and angle of the magnetic field.

The HMT is used as a device for measuring a head position and an angle of a user of a head mounted display device in a virtual reality (VR) of a game machine or an actual aircraft.
For example, in the VR technology, the VR space is experienced by visually recognizing an image that changes according to the movement of the head of the person wearing the head-mounted display device. In this case, the HMT is used to measure the position and orientation (angle) of the head of the wearer and change the display image of the head-mounted display device in accordance with the measurement result.

  In addition, in order to avoid losing sight of the rescue target that was discovered in the rescue operation by the rescue flying boat, the aiming image displayed by the head-mounted display device is locked when the rescue target corresponds, and thereafter Measures the position and angle of the head, calculates the positional relationship with the locked rescue target, and displays it so that the display device wearer does not lose sight of the rescue target. In this case, when calculating the positional relationship with the rescue target, in addition to the latitude, longitude, altitude, and attitude of the aircraft, the position and angle of the head of the person wearing the head-mounted display device are calculated. It is necessary to measure, and HMT is used.

  A head motion tracker (HMT) attached to a head-mounted display device uses a magnetic source to generate a magnetic field in the surrounding space, and measures magnetism with a magnetic sensor fixed to the head-mounted display device. A magnetic measurement system is disclosed that detects the current position and current angle of a magnetic sensor from the measured magnetic data, and consequently the current position and current angle of the head-mounted device (see Patent Document 1).

  FIG. 8 is a diagram schematically showing the configuration of a magnetic HMT. The HMT 100 is fixed to a magnetic source 101 that generates an alternating magnetic field using a three-axis coil, a head-mounted display device 103 that an HMT user sitting on a seat 102 attaches to the head, and a head-mounted display device 103. The magnetic sensor 104 includes a control unit 105 that controls the magnetic source 101 and the magnetic sensor 104 and has a function of calculating the position and angle of the magnetic sensor 104 based on magnetic data measured by the magnetic sensor 104. The In the HMT 100, an alternating magnetic field generated by the magnetic source 101 causes a magnetic change (magnetic data having a magnitude and a direction) unique to each position at each point in the space. By using the magnetic sensor 104 to measure the magnetism at the current position of the magnetic sensor 104 and comparing it with the magnetic data of each point in space, the positional relationship and angular relationship of the magnetic sensor 104 are calculated.

In the AC magnetic HMT, an origin and a coordinate system as a reference for a position and a reference direction as a reference for a direction are determined in advance. Specifically, the XYZ coordinate system is defined with the position of the magnetic source as the origin, and the X-axis direction is defined as the reference direction.
Based on the output of the magnetic sensor, the positional coordinate information of X, Y, and Z, which is the positional movement amount from the coordinate origin to the magnetic sensor, and the azimuth direction (rotation with respect to the X axis) which is the angular movement amount with respect to the reference direction of the magnetic sensor ), Angle information in the elevation direction (rotation with respect to the Y-axis), roll direction (rotation with respect to the Z-axis), and a head-mounted display device having a magnetic sensor fixed thereto, The position and angle with respect to the measurement origin and reference direction are obtained.

The magnetic data distribution in space can be obtained almost accurately by theoretical calculation based on electromagnetism theory (calculation based on Biosaval's law, etc.) in an ideal state where only the magnetic source and magnetic sensor that are magnetic field sources exist. it can.
However, when there is a conductive material such as metal around the magnetic source or sensor, the distribution of magnetic data is not simple, and the AC magnetic field is generated by the magnetic field induced by the eddy current generated in the conductive material. Magnetostriction will occur in the inside. In particular, in the case of a game machine or an aircraft, it is necessary to provide a metal seat because of the structure, and it is difficult to eliminate the conductive material from the periphery of the HMT, so magnetostriction due to the effect of the conductive material inevitably occurs. End up.

  Therefore, in order to remove the influence of the conductive substance, the magnetic data distribution (further, position error data and angle error data) at each measurement position is collected in advance using a magnetic mapping device. The magnetic mapping device moves the magnetic sensor to measurement positions (for example, measurement positions arranged in a grid) separated by a fixed interval by a moving device (moving stage) for moving the magnetic sensor, and magnetic data at each measurement position. Is obtained, and error data of the position and angle of each measurement point is acquired based on the output.

  As described above, the magnetic method can be used without any limitation as long as a magnetic field is generated in the space in which the magnetic sensor moves, but the magnetic data (position error data, angle error data) of the space in which the magnetic sensor is moved. Must be measured in advance by a magnetic mapping device.

  On the other hand, what optically measures the position and angle of a head-mounted display device is disclosed. That is, by attaching a marker composed of a position-specifying illuminator or reflector to the head-mounted display device, and performing stereo viewing using a camera, the marker position is optically read, thereby allowing the head-mounted display device to What measures a position and an angle is disclosed. For example, by attaching a reflector to a head-mounted display device, irradiating light from a light source, photographing the reflected light with a camera, and measuring the position and angle of the marker using the image data Have been disclosed (see Patent Document 2).

The optical measurement method is excellent in that it does not require magnetic mapping and is not affected by metal, etc., but it may cause misunderstanding of disturbance light and markers in a space with a lot of disturbance light. is there.
In addition, it is necessary to prevent a blind spot where the marker is not reflected on the camera. For example, a considerable number of markers that can be distinguished from each other (for example, a method using a plurality of markers with different emission wavelengths). Or a method for identifying individual markers from the positional information between the markers as described in Japanese Patent Application No. 2005-106458, which is a prior application of the same applicant), and is arranged in all directions on the outer surface of the head-mounted display device It is necessary to devise such that the markers appearing on the camera are always present. Therefore, when the number of markers increases, the electrical wiring of the head-mounted display device becomes complicated, and the weight becomes heavier than that of the magnetic system.

Furthermore, in the optical measurement method, in order to be able to reflect the entire space in which the marker moves, it is necessary to install a camera that optically reads the marker at a position slightly away from the user. When used in a seat or the like, it may be difficult to secure a space for camera installation other than during maintenance on the ground.
For this reason, the magnetic measurement method HMT and the optical measurement method HMT are separately used according to the place of use and purpose of use.
JP 2002-81904 A JP-T 9-506194

  As described above, the magnetic method and the optical method are separately used because they have advantages and disadvantages compared to the other, and in applications where the optical method cannot be used, the magnetic data measurement work of the surrounding space by the magnetic mapping device is performed. In addition, a magnetic HMT is used.

  By the way, in the case of adopting the magnetic system HMT, the magnetic data collection by the conventional magnetic mapping device is performed by moving the magnetic sensor at regular intervals by a motor-driven moving device (moving stage), thereby obtaining magnetic data at each point. Is actually measured. This measurement needs to be performed over the entire space in which the magnetic sensor (head) moves. Usually, more than 5000 measurement points are provided, and measurement is performed at each position. If the magnetic sensor is moved to each of the measurement points and the position is accurately determined, the magnetic sensor is stopped and the operation of acquiring data at each position is repeated. Therefore, this work requires a lot of time. For example, if measurement is performed by moving measurement points every 2 seconds, at least 10000 seconds (2 hours 47 minutes) are required to perform measurement at 5000 points or more. Even if magnetic mapping is performed, if the metal distribution in the measurement target region changes, the magnetic mapping must be performed again, and the same time is required each time.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic mapping apparatus capable of acquiring magnetic data (error data) necessary for using a magnetic HMT in a short time.

  The magnetic mapping apparatus of the present invention made to solve the above problems includes a magnetic source that generates a magnetic field similar to that when using a head motion tracker (HMT), a support, a support attached to the support, A magnetic sensor for measuring magnetic data, at least three marker groups attached to the outer surface of the support and fixed in position relative to the magnetic sensor, a pair of cameras for simultaneously viewing the three markers in stereo, and the pair of cameras The position coordinates of these three markers are determined based on the positions on the images of the three markers that are simultaneously captured in each image captured by the camera, and the position coordinates of the magnetic sensor are calculated based on the determined position coordinates of the three markers. Based on the magnetic sensor position calculation unit, the calculated position coordinates of the magnetic sensor, and the magnetic data measured when the camera image was taken. So that and a magnetic mapping unit for storing the mapping data.

Here, the shape of the support is not particularly limited as long as the magnetic sensor and the marker group can be fixed and the positional relationship between them can be made constant.
According to the present invention, the magnetic source generates the same magnetic field in the surrounding space as when the magnetic system HMT is actually used. In this state, the support to which the magnetic sensor and the marker group are attached is moved in a space where a magnetic field is generated. The support may be moved manually by the user, or a moving device may be used automatically. The movement may be performed randomly in an arbitrary direction, and it is not necessary to set the coordinates of the measurement point in advance and stop at the coordinate position. The movement range moves the entire space where the magnetic sensor may move when the HMT is used.

Each pair of cameras captures a moving support body one after another, and three common markers from a group of markers attached to the surface of the support body are photographed simultaneously by two cameras. The three common markers are projected on the two camera images taken at the same time. That is, the three markers are set to be viewed in stereo.
Since the object can uniquely determine the position and angle of the object at that time by determining the positions of the three points on the object, the magnetic sensor position angle calculation unit The angle information between each camera and the marker is obtained based on the position projected on the camera, and the position coordinates of the three markers at each time point are obtained by triangulation using the distance information between the cameras. By obtaining the position coordinates of each of the three markers, the position and angle of the support can be uniquely determined. By determining the position and angle of the support, the time point of the magnetic sensor fixed to the support is determined. The position coordinates can be uniquely determined.

In this manner, the position coordinates of the magnetic sensor at a certain time are obtained by optical measurement, and at the same time, magnetic data by the magnetic sensor at that time is collected. By repeating this operation, magnetic mapping data in which the position coordinates of the magnetic sensor and magnetic data for many points are associated is obtained. Since the measurement of position coordinates by optical measurement can be performed about 60 times per second, even when measuring 5000 points, it can be measured in about several minutes. The magnetic mapping unit accumulates the collected magnetic mapping data. The accumulated magnetic mapping data is used to create measurement error data.

  According to the above invention, there is no need to determine measurement points in advance and store them in the magnetic mapping apparatus, and the measurement preparation work can be simplified. Further, by obtaining the position coordinates of the magnetic sensor by optical measurement, even when there are a large number of measurement points, it is not necessary to stop and measure each measurement point, thereby greatly reducing the measurement time required for magnetic mapping.

(Means and effects for solving other problems)
In the above invention, a head-mounted support may be used as the support. As the head-mounted support body, specifically, a helmet dedicated to magnetic mapping can be used. For example, a head-mounted display device (HMD) actually used as an HMT may be provided with a marker.
By using a head-mounted support as the support, it is possible to imitate the movement of the head when actually using the HMT. Since mapping data can be collected, data in accordance with the actual situation can be obtained.

When a head-mounted support is used as the support, the marker group is scattered over the entire outer surface of the head-mounted support so that at least three markers are photographed by a pair of cameras from any direction. It may be arranged.
Thereby, even when the head-mounted support is extremely inclined, the three markers can be reliably viewed in stereo. In addition, the degree of freedom regarding the location of the pair of cameras can be increased.

In the above invention, the marker group may be configured such that individual markers are identified based on the positional relationship between the markers attached to the support.
According to this, since it is not necessary for the marker itself to have identification information for distinguishing from other markers, it is not necessary to manage the correspondence between the identification information and the marker arrangement, and the identification information is included. Inexpensive markers can be used.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and it goes without saying that various aspects are included without departing from the spirit of the present invention.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a magnetic mapping device according to an embodiment of the present invention, and FIG. 2 is a top view of a helmet that is a part of the magnetic mapping device. The magnetic mapping apparatus 1 includes a magnetic source 2 that generates an alternating magnetic field, a magnetic sensor 3 that detects magnetic data, a pair of cameras 12 and 14 that perform stereo vision, a helmet 16, and three LEDs 18 that are used as markers. (18a to 18c) and a control calculation unit 20 for controlling and calculating the magnetic source 2, the magnetic sensor 3, the camera 12, the camera 14, and the LED 18. When the functions executed by the control calculation unit 20 are described as functional blocks for convenience, a magnetic sensor position calculation unit 21 that calculates the position of the magnetic sensor 3 and a magnetic mapping unit 22 that accumulates magnetic mapping data are included.

The magnetic mapping apparatus 1 is set so as to form the same magnetic field as the HMT 100 described in FIG. For example, the magnetic source 2 uses the magnetic source 101 in FIG. 8 as it is, and the seat 4 uses the seat 102 in FIG. 8 as it is. As a result, the magnetic environment of the HMT 100 and the magnetic mapping device 1 is the same.
The magnetic sensor 3 has a pickup coil, and measures the magnitude and direction of magnetism at the current position as magnetic data.

The pair of cameras 12 and 14 are installed at a distance d (d is known from measurement) with a distance d so that the helmet 16 can be viewed in stereo from above the helmet 16. Assume that you are seeking.
Three LEDs 18 a to 18 c are fixed to the helmet 16 together with the magnetic sensor 3, and the helmet 16 itself becomes a support body that keeps the positional relationship between them constant. By obtaining the positional relationship (distance information) between the magnetic sensor 3 and the LEDs 18a to 18c on the helmet 16 in advance, if the positional coordinates of the three LEDs are obtained, the positional coordinates of the magnetic sensor 3 can be obtained. it can. The three LEDs 18a to 18c are attached at positions above the helmet so that when the helmet user performs a normal movement, the images are always reflected on the cameras 12 and 14 installed above.

  As the three LEDs 18a to 18c, those having different emission wavelengths (light emission colors) are used so that each of them can be distinguished from other adjacent LEDs. By attaching the LEDs so that at least two of the distance between the LEDs 18a and 18b, the distance between the LEDs 18b and 18c, and the distance between the LEDs 18c and 18a are different from each other (that is, three LEDs form an equilateral triangle). If the position coordinates of each LED are obtained by the calculation described later, the distance between the LEDs can be obtained and each LED can be specified. The identification information such as the emission wavelength may not be given to itself.

  The control unit 20 is configured by a computer including a CPU and a memory, and performs a control operation and a calculation operation of the magnetic mapping apparatus by executing a program stored in the memory.

The magnetic sensor position calculation unit 21, which is one of the functional blocks included in the control unit 20, is based on the positions on the images of the three LEDs that are simultaneously displayed in the pair of images taken by the pair of cameras 12 and 14. The position coordinates of the three LEDs are obtained by triangulation, and the calculation for calculating the position coordinates of the magnetic sensor 3 is performed based on the obtained position coordinates of the three LEDs. FIG. 3 is a diagram for explaining calculation of position coordinates by triangulation.
The coordinates of the LED 18x (18x is 18a, 18b, 18c) can be uniquely calculated if the direction angle αx from the camera 12 to the LED 18x, the direction angle βx from the camera 14 to the LED 18x, and the inter-camera distance d are known. The direction angle αx can be determined by the shooting direction of the camera 12 and the position of the LED 18x on the image projected by the camera 12. Similarly, the direction angle βx is projected by the shooting direction of the camera 14 and the camera 14. And the position of the LED 18x on the image. Further, since the inter-camera distance d is known, the position coordinates of the LED 18x can be calculated from αx, βx, d.

  By calculating the position coordinates of the three LEDs 18a, 18b, and 18c by the above calculation, the distance between the LEDs can be obtained by simple calculation. ) Is not attached, the LEDs 18a, 18b, and 18c are specified from the positional relationship information (difference in distance) between the LEDs.

  When the positions of the three LEDs 18a to 18c are specified and the coordinates are determined, the position and orientation of the helmet 16 at that time are uniquely determined. Since the position of the magnetic sensor 3 on the helmet 16 is fixed, the magnetic sensor position calculation unit 21 also uniquely identifies the position coordinates of the magnetic sensor 3 based on the position coordinates of the LEDs 18a, 18b, and 18c. .

  The magnetic mapping unit 22 performs control for associating the position coordinates with the magnetic data on the basis of the calculated position coordinates of the magnetic sensor 3 and the magnetic data measured at the time of capturing the camera image, and storing them in a memory (not shown). Do.

Next, the measurement operation by the magnetic mapping apparatus will be described.
The magnetic source 11 generates a magnetic field similar to that used when the head motion tracker (HMT) is used (S101).
Subsequently, the helmet 16 is moved in the magnetic field to collect magnetic data at a certain point in time, and at the same time, the position coordinates of the three LEDs 18a to 18c at that point are calculated (S102).
Subsequently, the position coordinates of the magnetic sensors are calculated based on the calculated position coordinates of the three LEDs 18a to 18c and the known positional relationship on the helmet 16 between the magnetic sensor 3 and the LEDs 18a to 18c (S103). ).

Subsequently, magnetic mapping data in which the position coordinates (calculated position coordinates) of the magnetic sensor 3 at the time when the magnetic data is collected is associated with the magnetic data is created and stored in a memory (not shown) (S104). .
Subsequently, the position coordinate of the magnetic sensor 3 is changed by the movement of the helmet 16 (S105).
Then, it is determined whether or not to continue the magnetic measurement with the new position coordinates. When the measurement is continued, the process returns to S102 and the same processing is repeated. When the measurement of the necessary area has already been completed, the process is terminated (S106).

  By the above measurement operation, while measuring magnetic data by the magnetic sensor, the position coordinates of the magnetic sensor 3 when the magnetic data is collected by an optical method are obtained, and magnetic mapping data is created from them. , So as to greatly reduce the measurement time.

(Embodiment 2)
In the first embodiment, the three LEDs 18a to 18c are attached as markers to the upper part of the helmet 16, and the pair of cameras 12 and 14 provided above them are used for stereo viewing. In this case, there is no problem in the movement range of the head in a normal operation, but when the helmet 16 is extremely tilted, any LED may be out of the field of view of any camera. When performing magnetic mapping, the cameras 12 and 14 may not be attached above the helmet 16 for some reason.
Therefore, no matter how the helmet is tilted or rotated, it is possible to reliably display the three markers on a pair of cameras at the same time. It is desirable to be able to see.

  Therefore, in this embodiment, as shown in FIG. 5, at least 4 or more LED18 is attached to the helmet 16a as a marker group. The appropriate number of LEDs to be attached varies depending on the size and shape of the helmet 16a and the installation positions of the pair of cameras 12 and 14, but in short, on the pair of images taken by the pair of cameras 12 and 14, three common The LED 18 should be studded to the extent that it is reliably included. For example, in FIG. 5, three LEDs 18a to 18c are simultaneously included in each camera image.

Each LED 18 needs to be distinguishable from other neighboring LEDs 18 in some way. In the present embodiment, as in the case of the first embodiment, the identification information is emitted at a different emission wavelength (emission color) for each LED.
As a result, the coordinates of the three LEDs 18a to 18c are obtained by performing the calculation for obtaining the position coordinates similar to those of the first embodiment using the three LEDs 18a to 18c that are commonly displayed in the pair of camera images at each time point. Furthermore, the position coordinates of the magnetic sensor 3 can be obtained, and magnetic mapping data can be obtained by associating with the magnetic data measured by the magnetic sensor 3.

(Embodiment 3)
In the second embodiment, each LED used includes identification information (for example, a difference in emission wavelength). However, when attaching each LED 18 to the helmet 16a, by making the distance between adjacent LEDs different from each other (by attaching the three LEDs so as not to form an equilateral triangle), identification information (for example, emission wavelength) Even if the difference between the LEDs is not included, the LED displayed on the camera image is identified by the method described below, and the position coordinates of each LED are obtained by using the calculation used in the first embodiment. Can do.

  If the LED itself does not contain identification information, first, as shown in FIG. 5, search for three LEDs that fall within the field of view of the two cameras 12 and 14 (however, the three positional relationships do not become equilateral triangles). It is turned on as a marker for use, and the other LED groups 18 are turned off. For convenience, it is assumed that these three LEDs are a set of LEDs 18a, 18b, and 18c.

  It is confirmed that three LEDs that are lit are reflected in the images A and B of the two cameras 12 and 14, respectively. FIG. 6 shows an image example at this time. Among the many LEDs, only three LEDs are lit. At this stage, it is known that the three LED images shown in the images A and B are each one of the LEDs 18a, 18b, and 18c, but each of the LED images is any of the three. It is not specified.

Therefore, an association for recognizing a common LED set (search marker set) between the images A and B is performed by prediction based on epipolar geometry. FIG. 7 is a diagram for explaining prediction based on epipolar geometry.
With the shooting direction of the camera 12 and the shooting direction of the camera 14 determined, the image A of the camera 12 has an LED 18x that is one of the LEDs 18a, 18b, and 18c that are lit (LED 18y and LED 18z are not shown). Is projected. At this time, assuming that there is a virtual straight line L connecting the camera 12 and the LED 18x, and this is projected by the camera 14, the virtual straight line LB is projected on the image B of the camera 14. The position of the virtual straight line LB on the image B is uniquely determined based on the position where the LED 18x appears in the image A and the relationship between the shooting direction of the camera 12 and the shooting direction of the camera 14. The image of the LED 18x exists at any position on the virtual straight line LB. Therefore, if there is an LED image that is displayed on the image B and is on the virtual straight line LB, it can be specified that it is an image of the LED 18x. Similarly, by specifying the image of the other two LEDs 18y and the image of the LED 18z, it is possible to associate a set of three LEDs 18x, LED 18y, and LED 18z displayed in the image A and the image B.

Subsequently, the position coordinates of the three search markers LED 18x, LED 18y, and LED 18z are calculated, and the three-dimensional positions of these three LEDs are specified. At this time, the position coordinate specifying method by triangulation described earlier with reference to FIG. 3 is used.
That is, when obtaining the position coordinates of the LED 18x, the direction angle αx can be determined by the shooting direction of the camera 12 and the position of the LED 18x in the image A, and the direction angle βx is determined by the shooting direction of the camera 14 and the LED 18x in the image B. It can be determined by the position of. Since the inter-camera distance d is known, the position coordinates of the LED 18x are calculated from αx, βx, d. Similarly, position coordinates are calculated for the LEDs 18y and 18z.

  Subsequently, the distance between the three search markers LED 18x, LED 18y, and LED 18z is calculated. Since the position coordinates of each of these three LEDs are calculated, the distance dx between the LED 18x and the LED 18y, the distance dy between the LED 18y and the LED 18z, and the distance dz between the LED 18z and the LED 18x can be obtained by simple calculation.

  Subsequently, the search markers for identifying whether the three search markers LED 18x, LED 18y, and LED 18z are the LEDs 18a, 18b, and 18c, respectively, are identified. The search marker is identified by comparing the distances dx, dy, dz between the LEDs 18x, LED 18y, LED 18z with the distances a, b, c between the LEDs 18a, 18b, 18c, which are known in advance. If the distances a, b, and c between the LEDs 18a, 18b, and 18c are all equal (that is, the positional relationship of the LEDs 18a, 18b, and 18c is an equilateral triangle), the search marker cannot be identified by the distance, but the LED 3 is turned on. Since one LED that does not have a regular triangular positional relationship is selected, identification is possible.

  Subsequently, when the three LEDs are identified and the LEDs 18a, 18b, and 18c are identified, the position and orientation of the helmet 16a can be identified from the position coordinates for these three LEDs. By specifying the position and orientation of the helmet, the position coordinates of the magnetic sensor 3 fixed to the helmet 16a can also be specified.

  According to the above procedure, the position coordinates of the magnetic sensor 3 can be obtained even when the LED itself does not contain identification information. Therefore, by performing the same processing as in the first and second embodiments, the magnetic Mapping can be performed.

  The present invention can be used when magnetic mapping is performed for a space using a magnetic HMT.

The block block diagram which shows the structure of the magnetic mapping apparatus which is one Embodiment of this invention. The figure which looked at the helmet in the magnetic mapping device of Drawing 1 from the upper part. The figure explaining calculation of the position coordinate of LED (marker) by triangulation. The flowchart explaining the process sequence by the magnetic mapping apparatus which is one Embodiment of this invention. The figure explaining the helmet and camera position used in other embodiment of this invention. The figure explaining the example of an image projected on a camera. The figure explaining the prediction based on epipolar geometry. The figure which shows the structure of HMT of a magnetic system.

Explanation of symbols

1: Magnetic mapping device 2: Magnetic source 3: Magnetic sensor 12, 14: Camera 16: Helmet 18: LED (marker)
20: Control calculation unit 21: Magnetic sensor position calculation unit 22: Magnetic mapping unit

Claims (4)

A magnetic source that generates a magnetic field similar to that used when using a head motion tracker, a support, a magnetic sensor that is attached to the support and measures magnetic data in the magnetic field, and is attached to the outer surface of the support. Based on at least three marker groups whose positions are fixed, a pair of cameras for simultaneously viewing the three markers in stereo, and positions on the images of the three markers simultaneously shown in the images taken by the pair of cameras The magnetic sensor position calculation unit that calculates the position coordinates of the three sensors and calculates the position coordinates of the magnetic sensor based on the determined position coordinates of the three markers, and the calculated position coordinates of the magnetic sensor and the photographing of the camera image Magnetic mapping data that stores magnetic mapping data that correlates position coordinates and magnetic data based on magnetic data measured at times Magnetic mapping apparatus being characterized in that a grayed section. The magnetic mapping apparatus according to claim 1, wherein a head-mounted support is used as the support. The marker group is arranged by being scattered all over the outer surface of the head-mounted support body so that at least three markers are photographed by a pair of cameras from any direction. Magnetic mapping device. 2. The magnetic mapping apparatus according to claim 1, wherein each marker is identified based on a positional relationship between the markers attached to the support.

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