WO2021104368A1 - 用于磁力计空间定位的系统和方法 - Google Patents

用于磁力计空间定位的系统和方法 Download PDF

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Publication number
WO2021104368A1
WO2021104368A1 PCT/CN2020/131747 CN2020131747W WO2021104368A1 WO 2021104368 A1 WO2021104368 A1 WO 2021104368A1 CN 2020131747 W CN2020131747 W CN 2020131747W WO 2021104368 A1 WO2021104368 A1 WO 2021104368A1
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Prior art keywords
magnetometer
positioning mark
mark
positioning
spatial
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PCT/CN2020/131747
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English (en)
French (fr)
Inventor
王帆
卓彦
杨思嘉
Original Assignee
中科知影(北京)科技有限公司
中国科学院生物物理研究所
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Application filed by 中科知影(北京)科技有限公司, 中国科学院生物物理研究所 filed Critical 中科知影(北京)科技有限公司
Priority to EP20892441.5A priority Critical patent/EP4067817A4/en
Priority to US17/780,750 priority patent/US20220409328A1/en
Publication of WO2021104368A1 publication Critical patent/WO2021104368A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C11/00—Photogrammetry or videogrammetry, e.g. stereogrammetry; Photographic surveying
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/002—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/39—Markers, e.g. radio-opaque or breast lesions markers
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/242—Detecting biomagnetic fields, e.g. magnetic fields produced by bioelectric currents
    • A61B5/245—Detecting biomagnetic fields, e.g. magnetic fields produced by bioelectric currents specially adapted for magnetoencephalographic [MEG] signals
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/6802—Sensor mounted on worn items
    • A61B5/6803—Head-worn items, e.g. helmets, masks, headphones or goggles
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/39—Markers, e.g. radio-opaque or breast lesions markers
    • A61B2090/3983—Reference marker arrangements for use with image guided surgery

Definitions

  • the invention relates to a system and method for spatial positioning of a magnetometer.
  • EEG detection In the field of electroencephalography (EGG) detection, it is usually necessary to install EEG detectors, such as patch electrodes, around the patient's head. Usually use manual marking or use a camera array to locate the position of the detector.
  • EEG detectors such as patch electrodes
  • the magnetic detector in the existing MEG technology uses a superconducting quantum interference device (SQUID) as the core device with high sensitivity (about 1fT/Hz 1/2 ), but it needs to use liquid helium to Maintaining superconducting working conditions results in very expensive equipment and operating costs.
  • the new type of magnetic detector the Optical-Pumping Magnetometer (OPM) polarizes the atomic gas with a beam of light, and uses the magnetic effect of the atomic spin to achieve the measurement of the weak magnetic field. The measurement accuracy reaches or exceeds the SQUID magnetometer. It can reach the level, and can work at room temperature, without liquid helium cooling, small in size and light in weight, and low-cost mass production can be realized through semiconductor technology.
  • the magnetometer is usually inserted and worn on the patient's helmet to fix the position of the magnetometer.
  • the positioning method of the EEG system can only be used to detect similar patch electrodes, which are small in thickness and can be regarded as a point in space. Detector.
  • Magnetometers are usually large in size. It is difficult to obtain a complete image due to the mutual occlusion between the magnetometers when shooting with a camera array. Therefore, it is difficult to locate the position of the magnetometer, and it is difficult to obtain the spatial orientation information of the magnetometer.
  • An embodiment of the present invention provides a system for spatial positioning of a magnetometer.
  • the system includes: a magnetometer configured to obtain magnetic field data related to brain magnetism or biomagnetic fields of other parts; The head or other parts of the body are fixedly arranged, and include at least one mounting part with orientation, allowing the magnetometer to be arranged on the mounting part at a first depth along a specific direction, respectively; a first positioning mark, the first positioning mark Is a non-rotationally symmetrical pattern, the first positioning marks are respectively set in association with the magnetometer; a photogrammetry system, the photogrammetry system includes a photographing device configured to be at least two photographing positions in a plurality of photographing positions Point to take the first image data of the first positioning mark through one or more of the photographing devices; and a controller configured to receive the first image data photographed by the photographing device and based on the pre-obtained The system parameters and the first image data calculate the spatial position and spatial orientation of the first positioning mark, and then calculate the spatial position and spatial orientation
  • the embodiment of the present invention provides a method for spatial positioning of the magnetometer of the system as described above, the method comprising the following steps: receiving a subject in a photogrammetric system, the subject wearing a magnetometer holder, And at least one magnetometer is provided on the magnetometer support; at least two of the multiple shooting locations are photographed by one or more photographing devices, respectively, and the first positioning marks set in association with the magnetometer are photographed
  • the first image data of the first positioning mark is a non-rotationally symmetric pattern; the first image data taken by the photographing device is received by the controller, and the first positioning mark is recognized by the controller; and based on the system parameters and the first
  • the image data calculates the spatial position and spatial orientation of the first positioning mark, and further calculates the spatial position and spatial orientation of the magnetometer.
  • Fig. 1 shows a schematic diagram of the installation of a magnetometer bracket according to an embodiment of the present invention
  • Fig. 2 shows a diagram of a set of coding marks according to an embodiment of the present invention
  • Fig. 3 shows a coding mark diagram according to another embodiment of the present invention.
  • Figure 4 shows a coding mark diagram according to another embodiment of the present invention.
  • 5A and 5B show the principle diagrams of an encoding method of an encoding mark according to an embodiment of the present invention
  • Fig. 6 shows a schematic diagram of a system for spatial positioning of a magnetometer according to an embodiment of the present invention
  • FIG. 7 shows a schematic diagram of the photographing device of the system shown in FIG. 6;
  • FIG. 8 shows a schematic diagram of a system for spatial positioning of a magnetometer according to another embodiment of the present invention.
  • Figure 9 shows the principle diagram of the three-dimensional coordinate measurement based on the dual photographs of the dual photographing device
  • Figure 10 shows a schematic diagram of images of coded markers at different shooting locations
  • Fig. 11 shows a flowchart of a method for spatial positioning of a magnetometer according to an embodiment of the present invention.
  • An electromagnetic digital instrument such as Fastrack system (Polhemus, Colchester, United States), which calculates the position and orientation of a receiver along with the movement of a receiver in an electromagnetic field, and the detection accuracy can reach 3.6mm.
  • electromagnetic digital instruments are highly sensitive to the environment. Metal objects in the environment can change and distort the electromagnetic field, which affects the integrity of the electromagnetic field, and thus has a greater impact on the detection accuracy.
  • the electromagnetic digital meter system is expensive and costly.
  • Ultrasonic digital meter which measures the distance by measuring the travel time of the ultrasonic pulse from the generator to the receiver to calculate the three-dimensional space position.
  • the ultrasonic digital instrument is also highly sensitive to the environment.
  • the ultrasonic digital instrument also needs to measure one by one measurement point, which takes a long time.
  • Photogrammetry such as Geodesic photogrammetry system (Electrical Geodesics Inc, United States), which uses a photogrammetric network to measure the spatial position of an object, in which one is installed in each of the 11 nodes of the photogrammetric sensor network
  • the camera can take a single photo at the same time, and then use the software of the system to use the triangulation transformation of the position of each detector in the two-dimensional photo to generate three-dimensional space coordinates.
  • This method has fast measurement speed and subjects can move.
  • this method can only locate the three-dimensional position points of the circular/ring electrodes for EEG, but cannot mark the three-dimensional orientation of each detector.
  • the mark of each detection channel can only be determined by the relative position relationship between the detection channels.
  • the system is a visible light illumination system located in the preparation room, which can only be used for electrode position calibration during the test preparation stage, and cannot be used for continuous position tracking during the experiment.
  • the magnetic detector in the existing MEG technology uses a superconducting quantum interference device (SQUID) as the core device with high sensitivity (about 1fT/Hz 1/2 ), but it needs to use liquid helium to Maintaining superconducting working conditions results in very expensive equipment and operating costs.
  • SQUID superconducting quantum interference device
  • OPM Optical-Pumping Magnetometer
  • the magnetometer based on the SERF effect is single-axis or multi-axis vector detection
  • the spatial positioning of the detector mainly focuses on the position positioning, and the positioning of the detector orientation is lacking.
  • the present invention proposes a system and method for spatial positioning of a magnetometer. Specifically, the present invention proposes a photogrammetry system and method based on encoding marks.
  • the "spatial positioning” in the present invention refers to the spatial position and orientation.
  • the “spatial position” in the present invention refers to the three-dimensional coordinates of an object in space or a relationship with an object. One or all of the relative positions of.
  • the “spatial orientation” in the present invention refers to the object's longitudinal axis as its axis, the vector direction in space and the angle at which the object rotates along the longitudinal axis.
  • non-rotationally symmetric pattern in the present invention refers to a pattern that cannot overlap itself after rotating the pattern around any center point at any angle (less than 360 degrees) in a plane.
  • An embodiment of the present invention provides a system for spatial positioning of a magnetometer, including: a magnetometer, configured to obtain magnetic field data related to brain magnetism or biomagnetic fields of other parts; and a magnetometer holder relative to the subject's head Or other parts of the body are fixedly arranged, and include at least one mounting part with orientation, allowing the magnetometer to be arranged on the mounting part at a first depth along a specific direction, respectively; a first positioning mark, the first positioning mark is not A rotationally symmetric pattern, the first positioning marks are respectively set in association with the magnetometer; a photogrammetry system, the photogrammetry system includes a photographing device configured to pass through at least two of a plurality of photographing positions One or more of the photographing devices photographing the first image data of the first positioning mark; and a controller configured to receive the first image data photographed by the photographing device, and based on pre-obtained system parameters Calculate the spatial position and spatial orientation of the first positioning mark with the first image data, and then calculate the spatial position and spatial orientation
  • the first positioning mark is fixedly arranged on the outer surface (such as the end and/or side) of the magnetometer, on the extension structure rigidly connected to the magnetometer, or with the aid of the magnetometer bracket fixed in position relative to the magnetometer Structurally.
  • the first positioning mark is arranged on the outermost end surface of the magnetometer, because this position is the easiest to be photographed by the photographing system.
  • Fig. 1 shows a schematic diagram of the installation of a magnetometer bracket according to an embodiment of the present invention
  • Fig. 2 shows a diagram of a set of coded marks according to an embodiment of the present invention
  • Fig. 3 shows another embodiment according to the present invention
  • Fig. 4 shows a coding mark diagram according to another embodiment of the present invention
  • FIG. 5A and 5B show a schematic diagram of a coding method for coding marks according to an embodiment of the present invention
  • Fig. 6 shows A schematic diagram of a system for spatial positioning of a magnetometer according to an embodiment of the present invention.
  • FIG. 7 shows a schematic diagram of a photographing device of the system shown in FIG. 6.
  • the system includes a magnetometer 1, a magnetometer holder 2, a first positioning mark 3, and a photogrammetric system 4.
  • the magnetometer 1 is used to obtain information related to brain magnetism.
  • the magnetometer 1 can also be used to obtain information related to the biomagnetic field of other parts, depending on the position where the magnetometer 1 is set.
  • the magnetometer holder 2 is in the form of a helmet, which is fixedly arranged relative to the subject's head, and includes at least one mounting portion (not shown) having an orientation that allows the magnetometer 1 to be separately aligned along a specific The direction is set on the mounting part at a first depth.
  • the mounting part is a mounting hole
  • the magnetometer 1 is fixedly mounted on the magnetometer bracket 2. Therefore, once the installation is completed, the relative position between the magnetometer 1 and the mounting hole can be fixed and determined.
  • the detector 11 of the magnetometer 1 is a vector detector, and the detected magnetic field information is vector information, which is different from the traditional EEG detection that only detects the scalar signal of the electrode. Therefore, it is necessary to measure the magnetic field vector information detected by the detector 11.
  • the magnetometer support 2 may be rigid or flexible.
  • the magnetometer holder 2 is rigid, that is, once worn on the subject's head, the relative positions of different magnetometers 1 on the magnetometer holder 2 will not easily change.
  • the magnetometer holder 2 may be made of a non-magnetic material, such as photosensitive toughened resin or nano-ceramic material.
  • the first positioning mark 3 is a first coding mark, which is fixedly arranged with respect to each magnetometer in a unique relationship, and the first positioning mark is a plane or a three-dimensional structure, and has the non-deformability of rotation and scaling.
  • each first positioning mark 3 has coded information, and the coded information has a one-to-one correspondence with its fixed magnetometer 1.
  • the system may also include one or more second positioning marks 6, and the second positioning marks 6 are fixedly arranged on the subject's head or other parts of the body, or connected to the subject's head or other parts of the body. On the extended structure through rigid connections.
  • the first positioning mark 3 is fixedly arranged at the end of the detector 11 of the magnetometer 1. Specifically, the first positioning mark 3 is fixedly arranged on the surface of the end of the detector 11 of the magnetometer 1, and the second positioning mark 6 is fixedly arranged on the center of the eyebrows and in front of the left and right ears of the subject's head, so that the magnetometers can be marked separately.
  • the position of the detector 11 of 1 and the position of the subject's head are used to perform the subsequent registration of the body part anatomy point and the magnetometer bracket.
  • the first positioning mark 3 can also be fixed at other positions, such as on the side of the detector 11 of the magnetometer 1, on the extension structure rigidly connected to the magnetometer 1, or on the magnetometer bracket 2 fixed in position relative to the magnetometer 1.
  • the auxiliary structure it depends on the requirements of the actual application, and the present invention is not limited thereto. On the premise of ensuring that the coding marks do not obscure each other, try to arrange larger shapes and more number of coding marks to obtain better positioning accuracy.
  • the second positioning mark 6 may not be provided, and the above registration may be performed by scanning a three-dimensional image of the body part by MRI, and the registration may be realized by matching software.
  • the first positioning mark 3 can be a plane or a three-dimensional structure, and has the non-deformability of rotation and scaling, and the first positioning mark 3 is a non-rotationally symmetric and/or non-axisymmetric pattern, so as to maintain the geometric structure at different distances and angles. Stability and uniqueness.
  • the first positioning mark 3 is an artificial mark with digitally encoded information, and has unique identity information, which can be automatically identified through image processing and other methods. In this embodiment, the first positioning mark 3 has a planar structure.
  • the first positioning mark 3 may be at least one of a circular code mark (also referred to as a "Schneider code mark"), a dot-shaped code mark, a square code mark, or a digital code mark.
  • Figures 2 to 4 exemplarily show the first positioning mark 3 according to the present invention.
  • the first positioning mark 3 may be a circular code mark as shown by mark AD in FIG. 2, or may be a dot-shaped code mark as shown by mark EG in FIG. 3, or a square as shown by mark J in FIG. Code mark, or digital code mark as shown by mark K in Figure 4.
  • the first positioning mark 3 may also be other coding marks without obvious geometric features as shown in the mark H-I in FIG. 4. It should be noted that what is shown above is only exemplary, and those skilled in the art can propose other encoding mark shapes based on the enlightenment of the above examples.
  • the first positioning mark 3 adopts a circular coding mark.
  • the circular coded mark is mainly composed of the center positioning mark and the coded bits surrounding it. These coded bits can be strip-shaped or dot-shaped. The coded bits are distributed on concentric circles centered on the center of the positioning mark, and the coding capacity can be increased by increasing the number of concentric circles or increasing the number of coded bits on the same circle.
  • the circular coding mark needs to reserve a part of the area as the reading reference, for example, the lower left area of the circular coding mark shown by marks A-D in FIG. 2.
  • the circular coding mark adopts the principle of binary coding, that is, 0, 1 coding is adopted. Each coding mark has a unique number corresponding to it.
  • the center positioning mark is surrounded by a circle with a unique code.
  • the code circle is equally divided into n equal parts (called n-bit codes), and each equal part is called a code bit.
  • Each coded bit can be regarded as a binary bit, black represents 0, white represents 1, and each bit can be 0 or 1, as shown in Figure 5B.
  • the code represented is an 8-bit code, and each coded mark consists of a total of 8-bit binary numbers. According to the rotation invariance requirements of the code, each coded bit can be used as the first bit of the 8-bit binary number.
  • 8-bit encoding has a total of 8 binary numbers corresponding to it. Since each encoding mark can only have a unique numerical identity, the minimum value of its corresponding decimal number is used as the encoding number of the encoding mark.
  • fast Hough transform can be used to obtain the position of the circle center O and the radius R, with O as the center and 2.5R as the radius, read the gray value in the clockwise or counterclockwise direction and convert it into Binary encoding.
  • the 8 binary numbers corresponding to the code shown in FIG. 5B are: 00100101, 01001010, 10010100, 00101001, 01010010, 10100100, 01001001, 10010010, respectively.
  • the coding rule can take the maximum value, or the coding bits can be combined in a counterclockwise direction, and the value of n can also be selected according to the actual coding capacity.
  • the photogrammetric system 4 can not only identify the coded mark and calibrate the position of the magnetometer 1, but also calibrate the three-dimensional orientation of the magnetometer 1 through perspective projection transformation.
  • the first positioning mark 3 may include a reflective material or an excited light material to provide sufficient contrast under the illumination light source or the excitation light source of the photogrammetric system 4.
  • the reflective material is, for example, a glass microbead reflective material, a microprism reflective material, and the like.
  • the excited light materials are, for example, fluorescent materials, up-conversion luminescent materials, phosphorescent materials, rare earth luminescent materials, and the like.
  • the first positioning mark 3 may include an active luminescent material, such as a light emitting diode (LED).
  • LED light emitting diode
  • the material of the first positioning mark 3 can be selected accordingly according to the illumination light source or the excitation light source of the photogrammetric system 4. For example, when the photogrammetric system 4 uses an infrared illuminating light source, the material of the first positioning mark 3 includes a material that reflects infrared light, and when the photogrammetric system 4 uses an excitation light source, the material of the first positioning mark 3 includes a fluorescent material, and the photogrammetric system 4 does not When the lighting device is used, the material of the first positioning mark 3 may include an active luminescent material.
  • special illuminating light source such as infrared
  • the corresponding special reflective material to make the coded mark can realize continuous recording of the mark before and during recording under special conditions such as a dark environment.
  • the second positioning mark 6 may have the same graphic characteristics as the first positioning mark 3 and/or the same material as the first positioning mark 3.
  • the photogrammetric system 4 can receive the magnetometer holder 2 therebetween to take pictures of the magnetometer holder 2, the magnetometer 1 mounted on it, and the first positioning mark 3, and the photogrammetric system 4 includes a photographing device 41.
  • the photographing device 41 is configured to photograph the first image data of the first positioning mark 3 through one or more of the photographing devices 41 at at least two of the multiple photographing locations 43 and to obtain the first image data Send to the controller.
  • the photographing device 41 may also be configured to photograph the second image data of the second positioning mark 6 through one or more photographing devices 41 at at least two of the multiple photographing locations 43 and to obtain the first image data. Second, the image data is sent to the controller.
  • the photogrammetric system 4 includes a structural support system 42 for installing a photographing device 41.
  • the structural support system 42 may be a frame structure that constitutes a half-polygon or hemisphere, so that the structural support system 42 is in a hemisphere or other
  • a plurality of shooting locations 43 are provided in the surface of the shape, and each shooting location 43 fixes at least one shooting device 41, or at least one shooting device can be manually or automatically moved between different shooting locations, or between adjacent shooting locations. Fix at least one photographing device in between, so as to realize fast multi-angle photography including coding marks and head/body shape.
  • the structural support system 42 is provided with multiple shooting locations 43 on a surface similar to a hemispherical shape. Each shooting location 43 fixes a photographing device 41, and can also be fixed between adjacent shooting locations 43.
  • a photographing device 41' is provided in FIG. 6, the structural support system 42 for installing a photographing device 41.
  • the structural support system 42 may be a frame structure that constitutes a half-poly
  • the structural support system 42 may be in the shape of a frame, including a plurality of nodes and connecting pieces connecting two adjacent nodes, and a shooting position 43 is provided on each node.
  • the connecting piece can be fixedly or movably installed with a photographing device, or without a photographing device.
  • the photographing device 41 may be a camera or a video camera. As shown in FIG. 7, the photographing device 41 may include a lighting device 411 and a lens 412.
  • the structural support system 42 may further include a position adjustment device 44 configured to adjust the position of the photogrammetry system 4 or the structure support system 42, for example, adjust the position of the structure support device 42 relative to the magnetometer bracket 2. Therefore, the lens 412 of the photographing device 41 can be moved closer to or farther away from the object to be photographed as required. Or the position adjustment device 44 can make the entire photogrammetry system 4 away from or close to the subject, so that the photogrammetry system 4 can be set in a position where the subject can be photographed after the subject is ready, and after the shooting is finished Keep away from the subject so that the subject can leave.
  • the position adjusting device 44 may include a hinge so that the entire photogrammetry system 4 can be pivoted, or may include a track, so as to drive the entire photogrammetry system 4 up and down and/or move in other directions.
  • the photogrammetric system 4 may include a reference device (not shown) for calibrating the initial position of the structural support system 42.
  • the photogrammetry system 4 includes a calibration device (not shown) for calibrating the initial position and shooting angle of the photography device to provide system parameters, thereby further improving the calibration accuracy of the system.
  • the photographing device 41 and its lighting device 411 can provide sufficient contrast to the first positioning mark 3 to distinguish it from the background object.
  • a three-dimensional model based on the same coordinate system space including the three can be established, outside of the magnetometer 1.
  • additional coding marks (second positioning mark 6) can be added to improve the positioning accuracy of the model reference points.
  • the encoding feature and perspective feature of the encoding mark connected to the magnetometer 1 are further identified, and the spatial position and orientation information of each magnetometer 1 relative to the aforementioned three-dimensional model is selected.
  • the three-dimensional model and information can be further used for registration calculation with the contour obtained by MRI, etc., so as to obtain the position and orientation information of the magnetometer 1 in the coordinate system based on anatomical images and the subject's body The relative position and orientation of the internal structure.
  • the system according to an embodiment of the present invention may further include a controller (not shown).
  • the controller stores pre-obtained system parameters.
  • the system parameters may preferably include the focal length of the photographing device 41 and the shooting angle of the photographing device 41. , The spatial position coordinates of the photographing device 41, the geometric size parameters of the magnetometer and/or the coding information of the first positioning mark 3, etc.
  • the controller is configured to receive the first image data captured by the photographing device 41, and calculate the spatial position and spatial orientation of the first positioning mark 3 based on the system parameters and the first image data, and then calculate the spatial position and spatial orientation of the magnetometer 1.
  • the controller receives the second image data 6 and calculates the spatial positioning of the subject’s head or other parts of the body according to the system parameters and the second image data 6, so as to realize the location of the subject’s head or other body parts.
  • the controller may be a Micro Controller Unit (MCU), a Field Programmable Gate Array (FPGA), or a digital signal processor, CPU, desktop computer, workstation, etc., which are commonly used in the field with data receiving and processing capabilities. Controller.
  • MCU Micro Controller Unit
  • FPGA Field Programmable Gate Array
  • FIG. 8 shows a schematic diagram of a system for spatial positioning of a magnetometer according to another embodiment of the present invention. The system of this embodiment will be described below in conjunction with FIG. 8.
  • the structural support system is fixedly arranged in the shielding room 5.
  • the shielding room 5 can isolate the influence of the external magnetic field, electromagnetic field or other interference sources on it, so as to ensure that the magnetometer 1 is not interfered by the change of the external magnetic field during the measurement process.
  • the subject sits in the shielded room 5 wearing a rigid or flexible magnetometer stand 2.
  • the structural support system includes, for example, a support frame 42 fixedly arranged on the top of the shielding room 5 and a support frame 42' fixedly arranged on the side of the shielding room 5, and the photographing device 41 can be configured to move manually or automatically between different shooting positions, thereby Realize multi-angle adjustable shooting. Therefore, part or all of the camera devices of the system can continuously track the position of the first positioning mark 3 of the magnetometer 1 and/or the position of the second positioning mark 6 on the subject's body part during the recording process, so as to be able to track the possible magnetometer
  • the relative position/orientation changes, the relative position/orientation changes of the magnetometer and the subject, and the relative position/orientation changes of the magnetometer and the shielded room were continuously recorded.
  • This information can be used for the calculation of the pointing field of the magnetometer holder 2, the calibration of the magnetometer 11 and the subject's head position, and the reduction of background magnetic field signals.
  • the use of special illuminating light source (such as infrared) and the corresponding special reflective material to make the coded mark can realize continuous recording of the mark before and during recording under special conditions such as a dark environment.
  • the purpose of encoding mark decoding and recognition is to determine the digital information of the center positioning mark, that is, the point number information, so that the image point with the same name can be found in different images in subsequent calculations, and the image coordinate information and digital information of the center positioning mark can be used to achieve other Automatic matching of non-coding tags.
  • FIG. 9 shows a principle diagram of a three-dimensional coordinate measurement based on dual photographs of a dual photographing device as an example of the present invention. That is, the measurement shown in FIG. 9 is based on the first image data of two first positioning marks captured by two photographing devices at two of the multiple photographing positions, and is calculated by a collinear or coplanar equation. The image points in the photo are the three-dimensional coordinates of the first and/or second positioning marks. This measurement principle is widely used in the field of computer vision.
  • the first image data of the first positioning mark can also be captured by multiple photography devices at more than two photography sites based on this principle for calculation.
  • the image points in the photo are calculated by the collinear equation.
  • the image space coordinate system O-xyz of the left camera device coincides with the object coordinate system
  • the image plane coordinate system is O 1 -X 1 Y 1
  • the effective focal length is f 1
  • the image space coordinate system of the right camera device O r -x r y r z r
  • the image plane coordinate system is O r -X r Y r
  • the effective focal length is f r .
  • the three-dimensional coordinates of the space point to be measured can be obtained by combining the above four equations.
  • Fig. 10 shows a schematic diagram of images of coded marks at different shooting locations. An example method of calculating the spatial orientation of the encoding mark is described below according to FIG. 10.
  • the first positioning marks 31, 32, 33 are images captured by photographing devices 41, 41', 41" from different angles.
  • the affine parameters of the first and/or second positioning marks can be calculated by an affine transformation method.
  • both the first and second positioning marks are coded marks.
  • projection imaging will be generated on the imaging plane. If the imaging plane is not parallel to the plane where the encoding mark is located, the projection imaging will be deformed, as shown in the first positioning mark 31 and the first positioning mark 33 in Figure 10
  • standardization is to reconstruct the elliptical image after projection deformation into a standard circular image, such as the first positioning mark 32 in FIG. 10.
  • the standardization of the circular coding mark area is to use the five ellipse parameters obtained by ellipse fitting to perform affine transformation within a certain range around the identified positioning mark, and reconstruct the ellipse mark image after projection deformation into a radius through affine transformation. Is the circular image of r.
  • the standardization of the coding marker area is the key to subsequent coding recognition, and the standardization is completed by the following formula:
  • x', y' are the pixel coordinates within a certain range of the center of the ellipse; x 0 , y 0 are the center coordinates of the standardized circle; P 1 , P 2 are the long and short semi-axes of the ellipse; x, y are the standardized pixel coordinates ; R is the radius of the standardized positioning mark, and ⁇ is the angle between the coding mark plane and the imaging plane.
  • the first positioning mark 32 of FIG. 10 shows a normalized image.
  • the decoding of the coded mark is to convert the different coded bit distribution of the coded band into a binary digital code, thereby determining a specific magnetometer number, and since the lens orientation (imaging plane orientation) of the photographing device 41 is known (calibrated),
  • the above-mentioned angle ⁇ (affine parameter), the orientation of the lens of the photographing device 41 and the angle between the major axis of the ellipse and the viewing frame of the photographing device can calculate the orientation of the encoding mark plane (shooting angle), that is, the end face of the magnetometer Orientation, by comparing the rotation angle between the imaged image and the standardized image, that is, the angle between the position of the encoded strip in the image after the image is standardized and the position of the strip in the reference reference image, the angle at which the magnetometer rotates along its longitudinal axis can be calculated , And then calculate the three-axis spatial orientation of the magnetometer.
  • the basic steps for calculating the spatial position and spatial orientation of the magnetometer based on the coded mark include:
  • Extract the outline of the coded marker is an ellipse.
  • the image feature extraction algorithm such as the ellipse fitting method or the gray-weighted centroid method
  • the image coordinates of the ellipse center are determined, and the ellipse target image that meets the feature points of the coding mark is extracted from the image.
  • image segmentation algorithms such as Canny operator
  • the contour information representing different regions is extracted from the image, and then the size, shape, gray level change and position distribution of the coded marker are combined to extract the ellipse that meets the conditions contour.
  • the unique identity of the magnetometer is determined according to the information on the coding mark, so that each magnetometer is classified and numbered.
  • the number of the coded marks is used to establish the corresponding matching relationship between the coded marks in the multiple images taken by one or more photographing devices.
  • the image matching algorithm based on coded markers can use the relaxed marking method matching algorithm, which needs to determine the similarity and compatibility of the corresponding coded markers. Similarity and compatibility calculation methods are commonly used algorithms in this field.
  • mismatches are eliminated. Eliminating mismatching can be based on the following criteria: similarity criteria, ambiguity criteria, or distance constraint error criteria.
  • the spatial position of each coding mark can be calculated based on the collinear equation or the coplanar equation, and the spatial orientation of each coding mark can be calculated based on the affine transformation (ellipse fitting) and the rotation angle. And since the geometry and size parameters of the magnetometer and the insertion position (that is, the position relative to the encoding mark) are known, the spatial position and spatial orientation of the magnetometer can be calculated.
  • the above steps can omit the steps of identifying and decoding the encoding mark, and the calculation methods for the remaining spatial positions and spatial orientations are similar.
  • Fig. 11 shows a flowchart of a method for spatial positioning of a magnetometer according to an embodiment of the present invention.
  • the method uses the system for magnetometer spatial positioning according to the foregoing embodiment, and the method includes the following steps:
  • step S101 the subject's head or other parts of the body wear the magnetometer holder 2 and receive it in the photogrammetry system 4.
  • the magnetometer holder 2 can be inserted into the magnetometer 1 in advance, or after the subject has finished wearing the magnetometer 1, the magnetometer 1 can be inserted into the mounting part of the magnetometer holder 2 at the first insertion depth along the insertion direction or other alternatives.
  • the installation part to install in place.
  • the magnetometer holder 2 is a helmet
  • the subject can wear the helmet and insert the magnetometer 1 into the mounting part on the helmet and insert it at a predetermined distance from the subject's scalp.
  • the predetermined distance is zero.
  • the position adjustment device 44 can be adjusted so that the subject wearing the helmet is located in the camera measurement system 4.
  • step S102 the first image data of the first positioning mark 3 is photographed at at least two of the multiple photographing positions 43 by one or more photographing devices 41.
  • This step can be performed only once, or performed in real time during the detection process of the magnetometer 1.
  • step S103 is performed only once, the obtained image data is a static image.
  • step S103 is performed in real time, continuous recording and tracking in the detection process can be realized.
  • step S103 the controller receives the first image data captured by the photographing device 41, and recognizes the first positioning mark through the controller.
  • the identification and decoding methods of the coded mark are as described above, and will not be repeated here. Since different first positioning marks have different encoding information, after identifying a certain first positioning mark, the magnetometer 1 corresponding to the first positioning mark can be identified, and then the identification and decoding of different magnetometers 1 can be completed .
  • step S104 the spatial position and spatial orientation of the first positioning mark are calculated based on the system parameters and the first image data, and then the spatial position and spatial orientation of the magnetometer are calculated.
  • the three-dimensional projection algorithm can be used to calculate the three-dimensional coordinates of the first positioning mark 3 and the plane orientation of the coding mark.
  • calculate the rotation orientation of the first positioning mark based on the recognition result, so that the spatial position and spatial orientation of the first positioning mark can be calculated, and then the spatial position and three-axis direction of the magnetometer can be calculated, and at the same time based on the received magnetometer
  • the magnetic field data calculates three-dimensional magnetic field vector information.
  • the method further includes calibrating and/or inputting system parameters.
  • the calibration system parameters mainly include calibrating the focal length, spatial position, and shooting angle of the camera 41, and inputting the encoding information of the first positioning mark 3 and the geometrical size parameters of the magnetometer.
  • the calibration system parameters further include inputting code information of the second positioning mark 6. Calibration and/or input of system parameters may be performed before each subject receives a measurement, or may be performed, for example, at a certain time interval, such as during the daily, weekly, or monthly regular maintenance of the system.
  • the encoded information of the first positioning mark 3 and the second positioning mark 6 includes the original information of the first positioning mark 3 and the second positioning mark 6 fixedly arranged on the end surface of the detector 11 of the magnetometer 1 or on the head of the subject.
  • An image which is an orthographic projection image without distortion and rotation, that is, the image taken from the front.
  • the calibration photographing device 41 is implemented by a calibration board, which is a commonly used device for calibration of a multi-camera industrial photogrammetric system.
  • the method further includes photographing the second image data of the second positioning mark 6 through one or more photographing devices 41 at at least two photographing positions among the plurality of photographing positions 43.
  • the second positioning mark 6 may have the same graphic characteristics as the first positioning mark 3 and/or the same material as the first positioning mark 3. Therefore, the identification and decoding method of the second positioning mark 6 is the same as that of the first positioning mark 3.
  • the controller receives the second image data and calculates the spatial positioning of the subject's head or other parts of the body according to the system parameters and the second image data, so as to realize the anatomical points and magnetic force of the subject's head or other parts of the body The registration of the meter bracket.
  • the method further includes fixing the structural support system 42 in the shielding room 5 and accommodating the subject in the shielding room 5.
  • the method further includes continuously receiving image data from the photogrammetry system through the controller during the magnetometer measurement process to perform real-time calculation, recording, or tracking of the position/orientation change of the magnetometer.
  • the data continuously received during the measurement of the magnetometer can be used for real-time calculation, recording or tracking of the possible position/orientation changes of the magnetometer during the recording process caused by the flexible magnetometer support, so as to establish more accurate three-dimensional dynamic process information of the magnetic field.
  • it can also be used for background noise reduction, motion artifact correction and a series of other post-processing operations.
  • the system and method for spatial positioning of magnetometers based on coded mark photogrammetry proposed by the present invention has the advantage that only one set of systems is required to calibrate any number of magnetometer positions, orientations, and relative human anatomy at the same time. To learn the positional relationship of the characteristics, there is no need to add an active calibration device to each detector, which eliminates the risk of electromagnetic interference caused by the calibration device to the magnetometer and greatly saves costs.
  • the system of the present invention based on coded mark photogrammetry is a passive and passive system compared to an active measurement device based on a built-in gyroscope or an electromagnetic digital meter, and there is no need to consider the electromagnetic interference that may be caused to the magnetometer.
  • the manufacturing cost is lower, and the replacement of the magnetometer or measuring device is quicker and easier. It has higher spatial resolution, angular resolution and lower calibration error, and can continuously record under the working state of the magnetometer.
  • the multi-camera-based photogrammetric optical system measuring device has a fast calibration speed, only a few seconds or less, and the efficiency is much higher than manual measurement, external electromagnetic digital instrument or ultrasonic digital instrument, etc. Passive calibration technology.
  • the system and method provided by the present invention have higher spatial/orientation measurement accuracy, and can automatically identify each magnetometer according to the encoding mark Corresponding to the channel number, the relative spatial position of the magnetometer is automatically recognized. There is no need to arrange the magnetometer according to the specific position correspondence relationship, which reduces the possibility of misoperation, and the efficiency of installation and replacement of the magnetometer is also greatly improved.

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Abstract

一种用于磁力计(1)空间定位的系统和方法，系统包括：磁力计(1)、磁力计支架(2)、第一定位标记(3)、摄影测量系统(4)以及控制器，磁力计支架(2)相对于受试者的头部或身体其他部位固定设置，并且包括具有取向的至少一个安装部，允许磁力计(1)分别沿特定方向以第一深度设置于安装部；第一定位标记(3)为非旋转对称图案；摄影测量系统(4)包括摄影装置(41)，配置为在多个拍摄位点中的至少两个拍摄位点通过一个或多个摄影装置(41)拍摄第一定位标记(3)的第一图像数据；控制器配置为接收摄影装置(41)拍摄的第一图像数据，并且基于预先获得的系统参数和第一图像数据计算第一定位标记(3)的空间位置，进而计算磁力计(1)的空间位置和空间取向。

Description

用于磁力计空间定位的系统和方法
本申请要求于2019年11月28日递交的中国专利申请第201911190087.2号的优先权，在此全文引用上述中国专利申请公开的内容以作为本申请的一部分。
技术领域
本发明涉及一种用于磁力计空间定位的系统和方法。
背景技术
在脑电图(electroencephalography，EGG)检测领域，通常需要在患者的头部周围安装探测脑电探测器，例如贴片电极。通常使用人工标记或使用照相机阵列实现来定位探测器的位置。
现有的MEG技术中的磁探测器，以超导量子干涉器件(superconducting quantum interference device，SQUID)为核心器件，灵敏度较高(约为1fT/Hz 1/2)，但其需要使用液氦来维持超导工作条件，导致设备成本和运行成本十分昂贵。而新型的磁探测器，即光泵磁力计(Optical-Pumping Magnetometer，OPM)通过光束极化原子气体，利用原子自旋的磁效应实现对微弱磁场的测量，测量精度达到甚至超过SQUID磁强计可以达到的水平，并且可以在室温环境下工作，无需液氦冷却，体积小重量轻，可通过半导体工艺实现低成本的大批量生产。
此外，在实际OPM应用中，磁力计通常插入佩戴在患者头盔，以固定磁力计的位置。为了进一步测得三维磁场矢量信息，需要获得磁力计的插入深度以及取向信息，然而，脑电系统的定位方法只能用于检测类似贴片电极这种厚度很小、空间上可以视为一个点的探测器。磁力计的尺寸通常较大，使用照相机阵列拍摄会由于磁力计之间的相互遮挡而无法获得完整的图像，因而难以定位磁力计的位置，也难以获得磁力计的空间取向信息。
发明内容
本发明的实施例提供一种用于磁力计空间定位的系统，该系统包括：磁力计，配置为获得与脑磁或其他部位生物磁场有关的磁场数据；磁力计支架，相 对于受试者的头部或身体其他部位固定设置，并且包括具有取向的至少一个安装部，允许所述磁力计分别沿特定方向以第一深度设置于所述安装部；第一定位标记，所述第一定位标记为非旋转对称图案，所述第一定位标记分别与所述磁力计相关联设置；摄影测量系统，所述摄影测量系统包括摄影装置，配置为在多个拍摄位点中的至少两个拍摄位点通过一个或多个所述摄影装置拍摄所述第一定位标记的第一图像数据；以及控制器，所述控制器配置为接收所述摄影装置拍摄的第一图像数据，并且基于预先获得的系统参数和所述第一图像数据计算所述第一定位标记的空间位置和空间取向，进而计算所述磁力计的空间位置和空间取向。
本发明的实施例提供一种用于如上所述的系统的磁力计空间定位的方法，该方法包括以下步骤：在摄影测量系统内接收受试者，所述受试者佩戴有磁力计支架，且所述磁力计支架上设置有至少一个磁力计；在多个拍摄位点中的至少两个拍摄位点通过一个或多个摄影装置拍摄分别与所述磁力计相关联设置的第一定位标记的第一图像数据，所述第一定位标记为非旋转对称图案；通过控制器接收摄影装置拍摄的第一图像数据，并通过控制器识别第一定位标记；以及基于系统参数和所述第一图像数据计算所述第一定位标记的空间位置和空间取向，进而计算所述磁力计的空间位置和空间取向。
附图说明
为了更清楚地说明本发明实施例的技术方案，下文中将对本发明实施例的附图进行简单介绍。其中，附图仅仅用于展示本发明的一些实施例，而非将本发明的全部实施例限制于此。
图1示出了根据本发明一实施例的磁力计支架的安装示意图；
图2示出了根据本发明一实施例的一组编码标记的图；
图3示出了根据本发明另一实施例的编码标记图；
图4示出了根据本发明又一实施例的编码标记图；
图5A和图5B示出了根据本发明一实施例的编码标记的编码方法原理图；
图6示出了根据本发明一实施例的用于磁力计空间定位的系统的示意图；
图7示出了图6所示的系统的摄影装置的示意图；
图8示出了根据本发明又一实施例的用于磁力计空间定位的系统的示意图；
图9示出了基于双摄影装置双相片的三维坐标测量原理图；
图10示出了不同拍摄位点的编码标记的图像的示意图；
图11示出了根据本发明一实施例的用于磁力计空间定位的方法的流程图。
具体实施方式
为了使得本发明的技术方案的目的、技术方案和优点更加清楚，下文中将结合本发明具体实施例的附图，对本发明实施例的技术方案进行清楚、完整地描述。附图中相同的附图标记代表相同的部件。需要说明的是，所描述的实施例是本发明的一部分实施例，而不是全部的实施例。基于所描述的本发明的实施例，本领域普通技术人员在无需创造性劳动的前提下所获得的所有其他实施例，都属于本发明保护的范围。
除非另作定义，此处使用的技术术语或者科学术语应当为本发明所属领域内具有一般技能的人士所理解的通常意义。本发明专利申请说明书以及权利要求书中使用的“第一”、“第二”以及类似的词语并不表示任何顺序、数量或者重要性，而只是用来区分不同的组成部分。同样，“一个”或者“一”等类似词语也不必然表示数量限制。“包括”或者“包含”等类似的词语意指出现该词前面的元件或物件涵盖出现在该词后面列举的元件或者物件和等同，而不排除其他元件或者物件。“连接”或者“相连”等类似的词语并非限定于物理的或者机械的连接，而是可以包括电性的连接，不管是直接的还是间接的。“上”、“下”、“左”、“右”等仅用于表示相对位置关系，当被描述对象的绝对位置改变后，则该相对位置关系也可能相应地改变。
在脑电图(electroencephalography，EGG)或脑磁图(magnetoencephalography，MEG)检测领域，通常需要在受试者的头部周围安装探测脑电或脑磁的探测器。然而，由于探测器的安装位置通常在受试者头皮表面，难以探测到大脑内的信号，因而信号难与解剖学空间相关联，也难以定位脑磁源。为了解决这一问题，研究者提出了探测器空间定位与磁共振成像(MRI)结合以同时获取受试者脑部解剖学构造和探测器空间方位，这种方案需要探测器空间数据与MRI的配准(co-registration)。
在脑电中，常见的探测器空间定位方法主要有以下四种：
1、人工直接测量，即用卡尺测量每个探测器和固定标记之间的位置，并计算每个探测器的笛卡尔坐标。这种方法不需要特定材料和设备、成本低，但 需要大量时间和人工进行测量，同时由于不可忽视的人为误差，测量精度很低。
2、电磁数字仪，例如Fastrack system(Polhemus，Colchester，United States)，其随着一接收器在电磁场中的移动来计算接收器的位置和取向，探测精度可达3.6mm。然而，电磁数字仪对环境敏感度较高，环境中的金属物体会使电磁场发生改变和扭曲，影响电磁场的完整性，从而对探测精度产生较大影响。同时，电磁数字仪系统昂贵，成本高。
3、超声数字仪，其通过测量超声脉冲从发生器到接收器之间行进的时间来测量距离，以计算三维空间位置。然而，受到环境温度和湿度的影响，超声数字仪同样对环境敏感度较高。此外，与电磁数字仪类似，超声数字仪也需要对逐个测量点进行测量，耗时较长。
4、摄影测量系统(photogrammetry)，例如Geodesic photogrammetry system(Electrical Geodesics Inc，United States)，其使用摄影测量网络来测量物体的空间位置，其中摄影测量传感器网络的11个节点中的每个安装有一个照相机，可以同时拍摄单张照片，再利用系统的软件来将二维照片中的每个探测器的位置利用三角变换生成三维空间坐标。该方法测量速度快、受试者可移动。但该方法只能定位脑电图用圆形/环形电极的三维空间位置点，而无法对每个探测器的三维空间朝向进行标记。此外，每个探测通道的标记只能通过探测通道之间的相对位置关系确定，如果发生变更电极位置或更换电极时，需要人工对照片中的探测器进行标记，容易导致操作错误。该系统为位于准备室内的，可见光照明系统，仅能用于测试准备阶段进行电极位置标定，无法在实验过程中进行连续位置跟踪。
现有的MEG技术中的磁探测器，以超导量子干涉器件(superconducting quantum interference device，SQUID)为核心器件，灵敏度较高(约为1fT/Hz 1/2)，但其需要使用液氦来维持超导工作条件，导致设备成本和运行成本十分昂贵。而新型的磁探测器，即光泵磁力计(Optical-Pumping Magnetometer，OPM)通过光束极化原子气体，利用原子自旋的磁效应实现对微弱磁场的测量，基于无自旋交换弛豫效应(SERF)的光泵磁力计测量精度达到甚至超过SQUID磁强计可以达到的水平，并且可以在室温环境下工作，无需液氦冷却，体积小重量轻，可通过半导体工艺实现低成本的大批量生产。
此外，由于基于SERF效应的磁力计为单轴或多轴矢量探测，在MEG检测领域中，为了进一步测得三维磁场矢量信息并进行准确的溯源定位，需要获 得探测器(磁力计)的空间位置和空间三维方向信息，而现有技术，尤其是脑电技术中，对于探测器的空间定位主要集中于位置定位，缺少对探测器取向的定位。基于此，本发明提出一种用于磁力计空间定位的系统和方法，具体地，本发明提出一种基于编码标记的摄影测量系统和方法。
需要说明的是，本发明所述的“空间定位”指的是空间位置和空间取向，进一步地，本发明所述的“空间位置”指的是物体在空间中的三维坐标或与某一物体的相对位置中的一个或全部。本发明所述的“空间取向”指的是物体以其纵向轴线为轴，在空间中的矢量方向以及物体沿该纵向轴线旋转的角度。
需要说明的是，本发明所述的“非旋转对称图案”指的是在平面内，将图案绕着任意中心点旋转任意角度(小于360度)之后均不能与自身重合的图案。
本发明的实施例提供一种用于磁力计空间定位的系统，包括：磁力计，配置为获得与脑磁或其他部位生物磁场有关的磁场数据；磁力计支架，相对于受试者的头部或身体其他部位固定设置，并且包括具有取向的至少一个安装部，允许所述磁力计分别沿特定方向以第一深度设置于所述安装部；第一定位标记，所述第一定位标记为非旋转对称图案，所述第一定位标记分别与所述磁力计相关联设置；摄影测量系统，所述摄影测量系统包括摄影装置，配置为在多个拍摄位点中的至少两个拍摄位点通过一个或多个所述摄影装置拍摄所述第一定位标记的第一图像数据；以及控制器，所述控制器配置为接收所述摄影装置拍摄的第一图像数据，并且基于预先获得的系统参数和所述第一图像数据计算所述第一定位标记的空间位置和空间取向，进而计算所述磁力计的空间位置和空间取向。
示例性地，第一定位标记固定设置在磁力计的磁力计外表面(例如末端和/或侧面)上、与磁力计刚性连接的延伸结构上或与磁力计相对位置固定的磁力计支架的辅助结构上。优选地是，所述第一定位标记设置在磁力计的最外侧端面上，因为这个位置最容易被拍摄系统拍摄。图1示出了根据本发明一实施例的磁力计支架的安装示意图，图2示出了根据本发明一实施例的一组编码标记的图，图3示出了根据本发明另一实施例的编码标记图，图4示出了根据本发明又一实施例的编码标记图，图5A和图5B示出了根据本发明一实施例的编码标记的编码方法原理图，图6示出了根据本发明一实施例的用于磁力计空间定位的系统的示意图，图7示出了图6所示的系统的摄影装置的示意图。
该系统包括磁力计1、磁力计支架2、第一定位标记3和摄影测量系统4。 磁力计1用于获得与脑磁有关的信息。此外，磁力计1也可以用于获得与其他部位生物磁场有关的信息，取决于磁力计1所设置的位置。如图1所示，例如，磁力计支架2是头盔形式，其相对于受试者的头部固定设置，并且包括具有取向的至少一个安装部(未示出)，允许磁力计1分别沿特定方向以第一深度设置于所述安装部。
示例性的，安装部为安装孔，磁力计1固定安装在磁力计支架2上，因此一旦完成安装，磁力计1与安装孔之间的相对位置就可以固定并确定。
需要说明的是，磁力计1的探测器11为矢量探测器，探测的磁场信息为矢量信息，这与传统的脑电探测仅探测电极标量信号不同。因此，需要测量探测器11探测到的磁场矢量信息。
可选地，磁力计支架2可以为刚性或柔性。在本实施例中，磁力计支架2为刚性的，即一旦佩戴在受试者头部，磁力计支架2上的不同磁力计1之间的相对位置不会轻易发生改变。磁力计支架2可以由非磁性材料制成，例如光敏增韧树脂或纳米陶瓷材料。
优选地，第一定位标记3为第一编码标记，以唯一的关系分别相对于每个磁力计固定设置，所述第一定位标记为平面或立体结构，具备旋转、缩放的不变形性，以实现在不同距离和角度下保持几何结构稳定性和唯一性。即，每个第一定位标记3具有编码信息，并且该编码信息与其固定设置的磁力计1一一对应。
示例性地，该系统还可以包括一个或多个第二定位标记6，第二定位标记6固定设置在受试者的头部或身体其他部位，或与受试者的头部或身体其他部位通过刚性连接的延展结构上。
在本实施例中，第一定位标记3固定设置于磁力计1的探测器11末端。具体地，第一定位标记3固定设置于磁力计1的探测器11末端的表面上，第二定位标记6固定设置于受试者头部的眉心和左右耳前，由此可以分别标记磁力计1的探测器11的位置和受试者头部所在的位置，以便进行后续的身体部位解剖学位点与磁力计支架的配准。
替代地，第一定位标记3也可以固定设置在其他位置，例如磁力计1的探测器11侧面、与磁力计1刚性连接的延伸结构上或与磁力计1相对位置固定的磁力计支架2的辅助结构上，取决于实际应用的要求，本发明并不以此为限。在保证编码标记不互相遮挡的前提下，尽量布置形状更大、数量更多的编码标 记以获得更好的定位精度。
替代地，也可以不设置第二定位标记6，以上配准可以通过MRI扫描身体部位的三维图像，并通过匹配软件实现配准。
第一定位标记3可以为平面或立体结构，具备旋转、缩放的不变形性，并且第一定位标记3为非旋转对称和/或非轴对称图案，以实现在不同距离和角度下保持几何结构稳定性和唯一性。第一定位标记3是一种自身带有数字编码信息的人工标记，具有唯一的身份信息，可以通过图像处理等方法对其进行自动识别。本实施例中，第一定位标记3为平面结构。
第一定位标记3可以为环形编码标记(又称为“Schneider编码标记”)、点状编码标记、方块编码标记或数字编码标记中的至少一种。图2至图4示例性地示出了本发明所述的第一定位标记3。例如，第一定位标记3可以是如图2中标记A-D所示的环形编码标记，或者可以是如图3中标记E-G所示的点状编码标记，或者如图4中标记J所示的方块编码标记，或者如图4中标记K所示的数字编码标记。此外，第一定位标记3还可以是如图4中标记H-I所示的没有明显几何特征的其他编码标记。需要说明的是，以上示出的仅是示例性的，本领域的技术人员可以基于上述示例的启示提出其他编码标记的形状。本实施例中，第一定位标记3采用环形编码标记。
下面将结合图5A和图5B描述环形编码标记的编码原理。如图2中标记A-D所示，环形编码标记主要由中心定位标记和围绕其周围的编码位组成，这些编码位可以是带状的，也可以是点状的。编码位分布在以定位标记中心为圆心的同心圆上，而且可以通过增加同心圆的数量或增加同一圆周上编码位的个数来提高编码容量。环形编码标记需要保留一部分区域作为读码基准，例如图2中标记A-D所示的环形编码标记的左下区域。环形编码标记采用二进制编码原理，即采用0、1编码。每个编码标记都有唯一的一个数字与之对应。
如图5A所示，中心定位标记被有着唯一编码的圆环包围着，编码圆环被等角度地分成n等分(称为n位编码)，每一等分称为编码位(code bit)，每一编码位可以看作是一个二进制位，黑色表示0，白色表示1，每一位均可以是0或1，如图5B中所示。其中，所表示的是8位编码，则每一个编码标记共有8位二进制数组成，根据编码的旋转不变性要求，每一个编码位均可以作为8位二进制数的第一位，对每一特定标记，8位编码共有8个二进制数与之对应，由于每个编码标记只能有唯一的数值身份，将其所对应的十进制数的最小值作 为该编码标记的编码数。
为了确定编码信息的读码起始位置，可以采用快速Hough变换得到圆心O的位置和半径R，以O为中心、2.5R为半径，沿顺时针或逆时针方向读取灰度值并转化成二进制编码。
现按照顺时针方向来组合编码位，则图5B所示的编码所对应的8个二进制数分别为:00100101、01001010、10010100、00101001、01010010，10100100、01001001、10010010。在这8个二进制数中，00100101所对应的十进制数最小(00100101 2＝37 10)，因此，该编码标记所对应的编码数就是37。本发明并不以此为限，编码规则可以取最大值，也可以按照逆时针方向来组合编码位，n的取值也可以根据实际编码容量来进行选择。可以选择合适的编码标记，使其足够容纳256通道以上的编码容量，同时具有合理的精密定位基准标记。通过这一套编码标记系统，摄影测量系统4在识别编码标记，标定磁力计1位置的同时，还可通过透视投影变换对磁力计1的空间三维朝向进行标定。
此外，第一定位标记3可以包含反光材料或受激发光材料，以提供在摄影测量系统4的照明光源或激发光源下的足够的对比度。反光材料例如为玻璃微珠反光材料、微棱镜反光材料等。受激发光材料例如为荧光材料、上转换发光材料、磷光材料、稀土发光材料等。
可选地，第一定位标记3可以包含主动发光材料，例如发光二极管(LED)。
第一定位标记3的材料可以根据摄影测量系统4的照明光源或激发光源而相应地进行选择。例如，摄影测量系统4采用红外照明光源时，第一定位标记3的材料包括反射红外光材料，摄影测量系统4采用激发光源时，第一定位标记3的材料包括荧光材料，摄影测量系统4不使用照明装置时，第一定位标记3的材料可以包括主动发光材料。使用特殊的照明光源(如红外线)和对应的特异反射性材料制作的编码标记，可以在要求黑暗环境等特殊条件下，实现对标记的记录前及记录中连续记录。
示例性地，第二定位标记6可以具有与第一定位标记3相同的图形特性和/或与第一定位标记3的材料相同。
如图6所示，摄影测量系统4可以在其间接收磁力计支架2以便对磁力计支架2、安装在其上的磁力计1和第一定位标记3进行拍摄，摄影测量系统4包括摄影装置41，摄影装置41配置为在多个拍摄位点43中的至少两个拍摄位点通过一个或多个所述摄影装置41拍摄第一定位标记3的第一图像数据并将 获得的第一图像数据发送给控制器。
示例性地，摄影装置41还可以配置为在多个拍摄位点43中的至少两个拍摄位点通过一个或多个摄影装置41拍摄第二定位标记6的第二图像数据并将获得的第二图像数据发送给控制器。
摄影测量系统4包括用于安装摄影装置41的结构支撑系统42，如图6所述，该结构支撑系统42可以为构成半个多边形或半球形的框架结构，使得结构支撑系统42在半球或其他形状表面内设置有多个拍摄位点43，每个拍摄位点43固定至少一个摄影装置41，或至少一个摄影装置能够在不同拍摄位点之间手动或自动移动，或相邻拍摄位点之间固定至少一个摄影装置，从而实现对包括编码标记和头部/身体外形在内的快速多角度拍摄。本实施例中，结构支撑系统42在类似半球形状的表面内设置有多个拍摄位点43，每个拍摄位点43固定一个摄影装置41，并且在相邻拍摄位点43之间还可以固定一个摄影装置41′。
示例性地，如图6所示，结构支撑系统42可以为框架状，包括多个节点和连接相邻两个节点的连接件，拍摄位点43设置在每个节点上。连接件可以固定或活动安装有摄影装置，或者不安装摄影装置。
摄影装置41可以是照相机或摄像机。如图7所示，摄影装置41可以包括照明装置411和镜头412。
可选地，结构支撑系统42还可以包括位置调节装置44，位置调节装置44构造为调节摄影测量系统4或结构支撑系统42的位置，例如，调节结构支撑装置42相对于磁力计支架2的位置，可以使摄影装置41的镜头412根据需要靠近或远离被拍摄物体。或者该位置调节装置44可以使得整个摄影测量系统4远离或接近受试者，以便在受试者准备好后将摄影测量系统4设置在能够对受试者进行拍摄的位置，以及在拍摄结束后远离受试者，以便于受试者离开。该位置调节装置44可以包括铰链，以便使得整个摄影测量系统4可以枢转，或者可以包括轨道，以便驱动整个摄影测量系统4升降和/或沿其他方向移动。
可选地，摄影测量系统4可以包括基准装置(未示出)，用于标定结构支撑系统42的初始位置。
可选地，摄影测量系统4包括标定装置(未示出)，用于标定所述摄影装置的初始位置和拍摄角度，以提供系统参数，从而进一步提高系统的标定精度。
摄影装置41及其照明装置411对第一定位标记3能提供足够的对比度以 区分其与背景物体。通过对于受试者头面部或其他部位外型轮廓、磁力计支架2及磁力计1在不同角度进行拍摄，从而建立包含三者在内的基于同一坐标系空间的三维模型，在磁力计1以外的部位如受试者头部的特定解剖学位点，或与这些位点相连接的固定结构上，可增加额外的编码标记(第二定位标记6)以提高模型基准点定位精度。基于这一模型，进一步通过识别与磁力计1相连的编码标记的编码特征及透视特征，取其每一个磁力计1相对于前述三维模型的空间位置及取向信息。此后可进一步通过该三维模型与信息，通过将其与MRI等获得的外形轮廓进行配准计算，从而获得磁力计1在基于解剖学影像的坐标系统中的位置与朝向信息和与受试者身体内部结构的相对位置及朝向关系。
此外，根据本发明一实施例的系统还可以包括控制器(未示出)，控制器存储有预先获得的系统参数，该系统参数优选地可以包括摄影装置41的焦距、摄影装置41的拍摄角度、摄影装置41的空间位置坐标、磁力计的几何尺寸参数和/或第一定位标记3的编码信息等，但是，这不是限制性的，这些参数也可以在每次测量时由操作者输入。控制器配置为接收摄影装置41拍摄的第一图像数据，并且基于系统参数和第一图像数据计算第一定位标记3的空间位置和空间取向，进而计算磁力计1的空间位置和空间取向。
示例性地，控制器接收第二图像数据6并且根据系统参数和第二图像数据6计算受试者的头部或身体其他部位的空间定位，以实现受试者的头部或身体其他部位的解剖学位点与磁力计支架2的配准。
示例性地，控制器可以是微控制单元(Micro Controller Unit,MCU)、现场可编程门阵列(FPGA)或数字信号处理器、CPU、台式电脑、工作站等本领域常见的具有数据接收和处理能力的控制器。
图8示出了根据本发明又一实施例的用于磁力计空间定位的系统的示意图，下面将结合图8来描述该实施例的系统。
以下仅就本实施例与图6所示出的实施例之间的不同之处进行说明，而其相似或相同之处则在此不再赘述。
在本实施例中，结构支撑系统固定设置在屏蔽室5内。屏蔽室5可以隔绝外界磁场，电磁场或其他干扰源对其中的影响，从而确保测量过程中磁力计1不受到外界磁场变化的干扰。受试者佩戴刚性或柔性的磁力计支架2坐在屏蔽室5内。
结构支撑系统例如包括固定设置在屏蔽室5顶部的支撑架42和固定设置在屏蔽室5侧面的支撑架42′，并且摄影装置41可以构造为在不同拍摄位点之间手动或自动移动，从而实现多角度可调的拍摄。因此，该系统的部分或全部摄影装置可以在记录过程中持续追踪磁力计1的第一定位标记3及/或受试者身体部位上的第二定位标记6的位置，从而对可能的磁力计间相对位置/朝向变化，磁力计与被试相对位置/朝向变化及磁力计与屏蔽室相对位置/朝向变化进行连续记录。
这些信息可以用于磁力计支架2的指向场计算，磁力计11与受试者头部位置校准及背景磁场信号消减等一系列用途。使用特殊的照明光源(如红外线)和对应的特异反射性材料制作的编码标记，可以在要求黑暗环境等特殊条件下，实现对标记的记录前及记录中连续记录。
编码标记解码识别的目的是确定中心定位标记的数字信息，即点的编号信息，使后续计算中能够在不同图像中找到同名像点，并根据中心定位标记的像坐标信息和数字信息来实现其他非编码标记的自动匹配。
图9示出了作为本发明的一个示例的基于双摄影装置双相片的三维坐标测量原理图。即，图9所示的测量是基于在多个拍摄位点中的两个拍摄位点通过两个摄影装置拍摄的两个第一定位标记的第一图像数据，通过共线或共面方程计算相片中的像点，即第一和/或第二定位标记的三维坐标。该测量原理在计算机视觉领域被广泛采用。
可选地，也可以基于该原理在多于两个摄影位点通过多个摄影装置拍摄第一定位标记的第一图像数据进行计算。
在本实施例中，通过共线方程计算相片中的像点，即第一和/或第二定位标记的三维坐标。如图9所示，设左摄影装置像空间坐标系O-xyz与物方坐标系重合，像平面坐标系为O 1-X 1Y 1，有效焦距为f 1，右摄影装置像空间坐标系O r-x ry rz r，像平面坐标系为O r-X rY r，有效焦距为f r。设物方点P在O-xyz中的坐标为(X,Y,Z)，其在左相片中对应的像点p在O-xyz中的坐标为(x,y,-f 1)，P在右相片中对应的像点pr在O r-X rY r中的坐标为(x r,y r,-f r)。通过共线或共面方程(数字近景工业摄影测量的常用方程)可以得到：
Figure PCTCN2020131747-appb-000001
Figure PCTCN2020131747-appb-000002
Figure PCTCN2020131747-appb-000003
Figure PCTCN2020131747-appb-000004
其中，
Figure PCTCN2020131747-appb-000005
分别为O-xyz坐标系与O r-X rY r坐标系之间的旋转矩阵和平移矩阵。
当知道摄影装置参数(包括焦距)、待测空间点在左右相片中的像坐标、旋转矩阵R和平移矩阵T，联立以上四式就可以得到待测空间点的三维坐标。
图10示出了不同拍摄位点的编码标记的图像的示意图。下面根据图10描述计算编码标记的空间取向的一个示例方法。如图10所示，第一定位标记31，32，33是由摄影装置41，41′，41″从不同角度拍摄获取的图像。
例如，可以通过仿射变换法计算第一和/或第二定位标记的仿射参数。在本实施例中，第一和第二定位标记均采用编码标记。编码标记经过相机镜头成像之后会在成像平面产生投影成像，如果成像平面不是平行于编码标记所在的平面，则投影成像会产生变形，如图10的第一定位标记31和第一定位标记33所示，标准化是把经过投影变形后的椭圆图像重构为标准的圆形图像，例如图10中的第一定位标记32。环形编码标记区的标准化是利用椭圆拟合所求的5个椭圆参数对识别出的定位标记周围一定范围内进行仿射变换，通过仿射变换使经投影变形后的椭圆标记图像重构为半径为r的圆形图像。编码标记区的标准化是后续编码识别的关键，标准化通过下式来完成：
Figure PCTCN2020131747-appb-000006
式中，x′、y′为椭圆中心一定范围内像素坐标；x 0、y 0为标准化圆形的中心坐标；P 1、P 2为椭圆的长短半轴；x、y为标准化后像素坐标；r为标准化后定位标记的半径，θ为编码标记平面与成像平面之间的角度。图10的第一定位标记32示出了标准化后的图像。
编码标记的解码是把编码带不同编码位分布转化为二进制数字编码，由此确定特定的磁力计编号，并且由于摄影装置41的镜头取向(成像平面取向) 是已知的(经过标定)，通过上述角度θ(仿射参数)、摄影装置41的镜头的取向以及椭圆长轴与摄影装置的取景框之间的夹角可以计算出编码标记平面的取向(拍摄角度)，即，磁力计端面的取向，通过对比成像图像与标准化图像之间的旋转角度，即该标记中图像标准化后编码条带位置与基准参照图像中条带位置的夹角，可以计算出磁力计沿其纵向轴线旋转的角度，进而计算出磁力计的三轴空间取向。
综上所述，基于编码标记计算磁力计的空间位置和空间取向的基本步骤包括：
提取编码标记轮廓。一般来说，编码标记图案经过摄影装置拍摄成像后，其中心定位标记为椭圆。根据图像特征提取算法，例如椭圆拟合法或者灰度加权质心法确定椭圆中心的图像坐标，并从图像中提取满足编码标记特征点的椭圆目标图像。接下来采用图像分割算法(例如Canny算子)进行图像分割，并在图像中提取代表不同区域的轮廓信息，然后接合编码标记的尺寸、形状、灰度变化及位置分布等特征提取满足条件的椭圆轮廓。
编码标记的解码，解码步骤在前述实施例的描述中已经具体叙述，在此不再赘述。
根据编码标记上的信息确定磁力计的唯一身份，从而对每个磁力计进行分类和编号。
利用编码标记的编号建立一个或多个摄影装置拍摄的多幅图像中编码标记间的对应匹配关系。基于编码标记的图像匹配算法可以采用松弛标记法匹配算法，该算法需要确定对应编码标记的相似性和相容性。相似性和相容性的计算方法是本领域的常用算法。
完成初始匹配后，剔除误匹配。剔除误匹配可以基于以下几个准则：相似性准则、模糊度准则或距离约束误差准则。
识别完成后，基于共线方程或共面方程可以计算每个编码标记的空间位置，基于仿射变换(椭圆拟合)和旋转角度可以计算出每个编码标记的空间取向。并且由于磁力计的几何形状尺寸参数和插入位置(即相对于编码标记的位置)是已知的，进而可以计算出磁力计的空间位置和空间取向。
在其他实施例中，当第一定位标记为不具有编码信息的非旋转对称标记时，上述步骤可以省略对于编码标记的识别和解码步骤，其余空间位置和空间取向的计算方法类似。
图11示出了根据本发明一实施例的用于磁力计空间定位的方法的流程图。该方法使用根据前述实施例的用于磁力计空间定位的系统，该方法包括以下步骤：
S101.在摄影测量系统4内接收受试者，所述受试者佩戴有磁力计支架2，且磁力计支架2上设置有至少一个磁力计1；
S102.在多个拍摄位点43中的至少两个拍摄位点通过一个或多个摄影装置41拍摄分别与磁力计1相关联设置的第一定位标记3的第一图像数据，第一定位标记3为非旋转对称图案；
S103.通过控制器接收摄影装置41拍摄的第一图像数据，并通过控制器识别第一定位标记3；以及
S104.基于系统参数和第一图像数据计算第一定位标记3的空间位置和空间取向，进而计算磁力计1的空间位置和空间取向。
在步骤S101中，受试者的头部或身体其他部位佩戴好磁力计支架2，并接收在摄影测量系统4内。磁力计支架2可以提前插入安装有磁力计1，或者在受试者佩戴完成后再插入磁力计1，磁力计1沿插入方向以第一插入深度插入磁力计支架2的安装部或其他替代性安装部中，以安装到位。在磁力计支架2为头盔的情况下，受试者可以佩戴上头盔并将磁力计1插入头盔上的安装部内并插入到距离受试者的头皮的预定距离处。可选的，该预定距离为零。然后，可调整位置调节装置44，使得佩戴有头盔的受试者位于摄像测量系统4中。
在步骤S102中，通过一个或多个摄影装置41在多个拍摄位点43中的至少两个拍摄位点拍摄第一定位标记3的第一图像数据。该步骤可以只进行一次，或者在磁力计1检测过程中实时进行。当只进行一次步骤S103时，获得的图像数据为静态图像。当实时进行步骤S103时，可以实现检测过程中的连续记录和追踪。
在步骤S103中，控制器接收摄影装置41拍摄的第一图像数据，并通过控制器识别第一定位标记。编码标记的识别和解码方法如前所述，在此不再赘述。由于不同的第一定位标记具有不同的编码信息，识别出某一第一定位标记之后即可识别出该第一定位标记所对应的磁力计1，进而可以完成对不同磁力计1的识别和解码。
在步骤S104中，基于系统参数和第一图像数据计算所述第一定位标记的空间位置和空间取向，进而计算磁力计的空间位置和空间取向。具体地，对识 别出的第一定位标记3，基于摄影装置41的初始位置和拍摄角度，采用三维投影算法可以计算出该第一定位标记3所处的三维坐标及编码标记所处平面取向，并基于识别结果计算该第一定位标记的旋转取向，从而可以计算出该第一定位标记的空间位置和空间取向，进而计算磁力计的空间位置和三轴方向，同时基于接收的该磁力计的磁场数据计算三维磁场矢量信息。
可选地，该方法还包括标定和/或输入系统参数，标定系统参数主要包括标定摄影装置41的焦距、空间位置和拍摄角度，以及输入第一定位标记3编码信息和磁力计的几何尺寸参数。示例性地，当该系统包括第二定位标记6时，标定系统参数还包括输入第二定位标记6的编码信息。标定和/或输入系统参数可以在每次受试者接收测量之前进行，也可以例如按一定时间间隔进行，例如在系统每日、每周或每月的日常定期维护时进行。第一定位标记3和第二定位标记6的编码信息包括固定设置例如在磁力计1的探测器11末端表面上或受试者头部上的第一定位标记3和第二定位标记6的原始图像，该图像为未经变形和旋转的正投影图像，即正面拍摄时的图像。
具体地，标定摄影装置41采用标定板实现，标定板是多相机工业摄影测量系统标定常用的装置。
可选地，该方法还包括在多个拍摄位点43中的至少两个拍摄位点通过一个或多个摄影装置41拍摄第二定位标记6的第二图像数据。第二定位标记6可以具有与第一定位标记3相同的图形特性和/或与第一定位标记3的材料相同。因此，对于第二定位标记6的识别与解码方法与第一定位标记3相同。通过控制器接收第二图像数据并且根据系统参数和第二图像数据计算受试者的头部或身体其他部位的空间定位，以实现受试者的头部或身体其他部位的解剖学位点与磁力计支架的配准。
可选地，该方法还包括在屏蔽室5内固定设置结构支撑系统42，并将受试者容纳在屏蔽室5内。
可选地，该方法还包括在磁力计测量过程中通过控制器持续接收来自摄影测量系统的图像数据以对磁力计的位置/取向变化进行实时计算、记录或追踪。磁力计测量过程中持续接收的数据可用于对柔性磁力计支架导致的磁力计在记录过程中可能的位置/取向变化进行实时计算、记录或追踪，以建立更准确的磁场动态三维过程信息。此外，也可用于背景降噪，运动伪影修正等一系列其他后处理操作。
综上所述，本发明提出的基于编码标记摄影测量、用于磁力计空间定位的系统和方法，优点在于，仅需一套系统在即可同时标定任意数量的磁力计位置，指向和相对人体解剖学特征的位置关系，无需在每个探测器上加入主动标定装置，去除了标定装置可能对磁力计造成电磁干扰的风险并大幅节省了成本。
此外，本发明的基于编码标记摄影测量的系统，相比基于内置陀螺仪或者电磁数字仪的主动测量装置，为被动无源系统，无需考虑对磁力计可能造成的电磁干扰，每个磁力计的制造成本更低，更换磁力计或测量装置更快捷简便，拥有更高的空间分辨率和角分辨率以及更低的标定误差，可在磁力计工作状态下进行持续记录。相比于其他被动标定方式，基于多摄像头的摄影测量光学系统测量装置，标定速度快，仅需几秒钟或更低，效率远高于手动测量，外置电磁数字仪或超声数字仪等其他被动标定技术。
相比于深度摄像头，手持/多机位结构光等无标记光学被动标定方法，本发明提供的系统和方法具备更高的空间/取向测量精度，且可根据编码标记自动识别每个磁力计的对应通道编号，自动识别磁力计的空间相对位置，无需按特定位置对应关系排布磁力计，减少了误操作可能性，在安装和更换磁力计时的效率也有很大提升。
上文中参照优选的实施例详细描述了本发明所提出的用于磁力计空间定位的系统和方法的示范性实施方式，然而本领域技术人员可理解的是，在不背离本发明理念的前提下，可以对上述具体实施例做出多种变型和改型，例如，尽管上面详细描述了一种通过定位标记来计算磁力计的空间位置和取向的算法，但是，本发明并不局限于此，而是可以采用任何有利的算法或者简化方法，只要该算法可以达到所需的计算精度即可。另外，也可以对本发明各个方面提出的各种技术特征、结构进行多种组合，而不超出本发明的保护范围，本发明的保护范围由所附的权利要求确定。

Claims (32)

  1. 一种用于磁力计空间定位的系统，包括：
    磁力计，配置为获得与脑磁或其他部位生物磁场有关的磁场数据；
    磁力计支架，相对于受试者的头部或身体其他部位固定设置，并且包括具有取向的至少一个安装部，允许所述磁力计分别沿特定方向以第一深度设置于所述安装部；
    第一定位标记，所述第一定位标记为非旋转对称图案，所述第一定位标记分别与所述磁力计相关联设置；
    摄影测量系统，所述摄影测量系统包括摄影装置，配置为在多个拍摄位点中的至少两个拍摄位点通过一个或多个所述摄影装置拍摄所述第一定位标记的第一图像数据；以及
    控制器，所述控制器配置为接收所述摄影装置拍摄的第一图像数据，并且基于预先获得的系统参数和所述第一图像数据计算所述第一定位标记的空间位置和空间取向，进而计算所述磁力计的空间位置和空间取向。
  2. 根据权利要求1所述的系统，其中，所述系统参数包括所述摄影装置的焦距、所述摄影装置的拍摄角度、所述摄影装置的空间位置坐标、所述第一定位标记的编码信息和/或所述磁力计的几何尺寸参数。
  3. 根据权利要求2所述的系统，其中，所述第一定位标记固定设置在所述磁力计的外表面上、与所述磁力计刚性连接的延伸结构上或者与所述磁力计相对位置固定的所述磁力计支架的辅助结构上。
  4. 根据权利要求3所述的系统，其中，所述第一定位标记为第一编码标记，以唯一的关系分别相对于每个磁力计固定设置，所述第一定位标记为平面或立体结构，具备旋转、缩放的不变形性，以实现在不同距离和角度下保持几何结构稳定性和唯一性。
  5. 根据权利要求4所述的系统，其中，所述第一定位标记为环形编码标记、点状编码标记、方块编码标记或数字编码标记中的至少一种。
  6. 根据权利要求4所述的系统，其中，所述第一定位标记包含反光材料或受激发光材料，以提供在照明光源或激发光源下的足够的对比度。
  7. 根据权利要求4所述的系统，其中，所述第一定位标记包含主动发光材料。
  8. 根据权利要求1-7中任一项所述的系统，还包括：
    一个或多个第二定位标记，所述第二定位标记为非旋转对称图案，固定设置在受试者的头部或身体其他部位，或与受试者的头部或身体其他部位通过刚性连接的延展结构上，其中，
    所述摄影装置配置为在多个拍摄位点中的至少两个拍摄位点通过一个或多个所述摄影装置拍摄所述第二定位标记的第二图像数据，所述控制器接收所述第二图像数据并且根据所述系统参数和所述第二图像数据计算受试者的头部或身体其他部位的空间定位，以实现受试者的头部或身体其他部位的解剖学位点与所述磁力计支架的配准。
  9. 根据权利要求8所述的系统，其中，所述第二定位标记为第二编码标记，以唯一的关系分别相对于受试者的头部或身体其他部位固定设置。
  10. 根据权利要求9所述的系统，其中，所述第二定位标记具有与所述第一定位标记相同的图形特性和/或与所述第一定位标记的材料相同。
  11. 根据权利要求2所述的系统，其中，所述摄影测量系统还包括：
    标定装置，用于标定所述摄影装置的初始位置和拍摄角度。
  12. 根据权利要求1所述的系统，其中，所述摄影测量系统还包括：
    结构支撑系统，其在半球或其他形状表面内设置有多个拍摄位点，每个拍摄位点固定至少一个摄影装置，和/或至少一个摄影装置能够在不同拍摄位点之间手动或自动移动，和/或相邻拍摄位点之间固定至少一个摄影装置。
  13. 根据权利要求12所述的系统，其中，所述结构支撑系统包括位置调节装置，该位置调节装置构造为移动或调整所述摄影测量系统的位置。
  14. 根据权利要求12所述的系统，其中，所述结构支撑系统固定设置在屏蔽室内。
  15. 根据权利要求14所示的系统，其中，所述控制器配置为在所述磁力计测量过程中持续接收来自摄影测量系统的图像数据以对磁力计的位置和/或取向变化进行实时计算、记录或追踪。
  16. 根据权利要求12所述的系统，其中，所述摄影测量系统还包括基准装置，用于标定所述结构支撑系统的初始位置。
  17. 根据权利要求1所述的系统，其中，所述摄影装置为照相机或摄像机。
  18. 根据权利要求1所述的系统，其中，所述磁力计支架为刚性或柔性。
  19. 根据权利要求1至18中任一项所述的系统，其中，所述磁力计支架 为头盔。
  20. 根据权利要求2-19中任一项所述的系统，其中，所述控制器被构造成通过共线或共面方程分别计算所述第一定位标记的三维坐标，以及根据所计算的第一定位标记的三维坐标和所述磁力计的几何参数计算每个磁力计的空间位置。
  21. 根据权利要求20所述的系统，其中，所述控制器被构造成：
    通过仿射变换法计算所述第一定位标记的仿射参数；
    通过所述仿射参数、所述系统参数和所述第一图像数据计算所述第一定位标记所处平面的空间取向；
    通过对比所述第一图像数据和基准参照图像的旋转角度，计算所述第一定位标记在其所处平面内的旋转角度，从而计算所述第一定位标记的空间取向；以及
    根据磁力计的几何参数和第一定位标记的空间取向计算磁力计的空间取向。
  22. 一种磁力计空间定位的方法，包括以下步骤：
    在摄影测量系统内接收受试者，所述受试者佩戴有磁力计支架，且所述磁力计支架上设置有至少一个磁力计；
    在多个拍摄位点中的至少两个拍摄位点通过一个或多个摄影装置拍摄分别与所述磁力计相关联设置的第一定位标记的第一图像数据，所述第一定位标记为非旋转对称图案；
    通过控制器接收摄影装置拍摄的第一图像数据，并通过控制器识别第一定位标记；以及
    基于系统参数和所述第一图像数据计算所述第一定位标记的空间位置和空间取向，进而计算所述磁力计的空间位置和空间取向。
  23. 根据权利要求22所述的方法，其中，计算所述第一定位标记的空间位置包括通过共线或共面方程分别计算所述第一定位标记的三维坐标；以及
    计算所述磁力计的空间位置包括根据所述磁力计的几何参数和所述第一定位标记的三维坐标计算所述磁力计的空间位置。
  24. 根据权利要求22所述的方法，其中，计算所述第一定位标记的空间取向包括：
    通过仿射变换法计算所述第一定位标记的仿射参数；
    通过所述仿射参数、所述系统参数和所述第一图像数据计算所述第一定位标记所处平面的空间取向；
    通过对比所述第一图像数据和基准参照图像的旋转角度，计算所述第一定位标记在其所处平面内的旋转角度，从而计算所述第一定位标记的空间取向；以及
    根据磁力计的几何参数和第一定位标记的空间取向来计算所述磁力计的空间取向。
  25. 根据权利要求22所述的方法，其中，所述第一定位标记固定设置在所述磁力计的外表面上、与所述磁力计刚性连接的延伸结构上或者与所述磁力计相对位置固定的所述磁力计支架的辅助结构上。
  26. 根据权利要求25所述的方法，其中，所述第一定位标记为第一编码标记，以唯一的关系分别相对于每个磁力计固定设置，所述第一定位标记为平面或立体结构，具备旋转、缩放的不变形性，以实现在不同距离和角度下保持几何结构稳定性和唯一性。
  27. 根据权利要求22所述的方法，还包括：
    在多个拍摄位点中的至少两个拍摄位点通过一个或多个所述摄影装置拍摄第二定位标记的第二图像数据；
    通过控制器接收所述第二图像数据并且根据所述系统参数和所述第二图像数据计算受试者的头部或身体其他部位的空间定位，以实现受试者的头部或身体其他部位的解剖学位点与磁力计支架的配准。
  28. 根据权利要求27所述的方法，其中，所述第二定位标记为第二编码标记，以唯一的关系分别相对于受试者的头部或身体其他部位固定设置，所述第二定位标记具有与所述第一定位标记相同的图形特性和/或与所述第一定位标记的材料相同，并且计算所述第二定位标记的空间位置和空间取向的方法与所述第一定位标记的计算方法相同。
  29. 根据权利要求22所述的方法，还包括：
    在磁力计控制器持续接收来自拍摄测量系统的图像数据以对磁力计的位置和/或取向变化进行实时计算、记录或追踪。
  30. 根据权利要求22所述的方法，其中，所述标定系统参数包括标定所述摄影装置的拍摄角度、所述摄影装置的空间位置坐标、所述第一定位标记的编码信息和/或所述磁力计的几何尺寸参数。
  31. 根据权利要求22所述的方法，还包括：
    标定和/或输入系统参数，其中，所述系统参数包括所述摄影装置的焦距、所述摄影装置的拍摄角度、所述摄影装置的空间位置坐标、所述第一定位标记的编码信息和/或所述磁力计的几何尺寸参数。
  32. 根据权利要求31所述的方法，其中，所述标定和/或输入系统参数按一定时间间隔进行，或在每次对受试者进行测试之前进行。
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