Point set matching method and device for body surface positioning band

Abstract

The invention provides a point set matching method and device for a body surface positioning band. The method is applied to the field of medical surgical robot positioning. The method comprises the following steps: acquiring a preoperative body surface positioning point image and an intraoperative body surface positioning point image; respectively identifying the plurality of positioning points to obtain a source point set and a target point set; performing plane fitting on the source point set and the target point set to obtain a source point set fitting plane and a target point set fitting plane; respectively acquiring two normal vectors of the two fitting planes, and determining the same normal vector as a positive direction in the fitting planes of the source point set and the target point set; determining sequence information of a plurality of positioning points in the source point set and sequence information of corresponding angles; determining sequence information of a plurality of positioning points in the target point set and sequence information of corresponding angles; and determining the sequence information of one matched positioning point from the sequence information according to the sequence information of each group of angles in the target point set and the sequence information of the angles in the source point set. According to the invention, the accuracy of symmetric point set matching is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of positioning of medical surgical robots, and in particular to a point set matching method and device for a body surface positioning belt. Background Art

[0002] In the field of engineering, point set (or point cloud) registration technology plays a vital role. Its core goal is to find a transformation matrix that can accurately overlap the source point set with the target point set. The essence of this process is to accurately establish a one-to-one correspondence between two sets of point sets, namely point set matching. Point set matching algorithm, as a mathematical tool for this task, is committed to exploring the optimal point set matching solution through precise calculation and analysis to ensure high accuracy and reliability of registration.

[0003] Point set matching algorithms are widely used in many fields, especially in the surface positioning belt of medical surgical robots. In medical practice, a surface positioning belt composed of reflective small balls with positioning marks is often used. It is named according to the number of small balls. If there are n small balls, it is called an n-point positioning belt. Before the operation, the positioning belt is attached to the patient's body for CT scanning. The CT coordinates of n small balls can be extracted from the CT image as the source point set; during the operation, the NDI infrared navigation and positioning system is responsible for capturing the world coordinates of these small balls to form the target point set. In order to accurately perform the operation, the two sets of point set coordinates need to be matched. However, the traditional point set matching algorithm has obvious shortcomings in dealing with certain specific situations. For example, when dealing with a point set with axial symmetry, the traditional algorithm often leads to matching failure due to the inability to accurately distinguish symmetrical points, thus affecting the accuracy and safety of the operation. Summary of the invention

[0004] In view of this, the present invention provides a point set matching method and device for a body surface positioning belt, comprising:

[0005] Acquire a preoperative body surface positioning point image and an intraoperative body surface positioning point image of a body surface positioning band attached to the surface of the human body;

[0006] Respectively identifying a plurality of positioning points in the preoperative body surface positioning point image and the intraoperative body surface positioning point image to obtain a source point set and a target point set;

[0007] Performing plane fitting on the source point set and the target point set respectively to obtain a source point set fitting plane and a target point set fitting plane;

[0008] Obtain two normal vectors of two fitting planes respectively, and determine the same normal vector in the source point set fitting plane and the target point set fitting plane as the positive direction;

[0009] Taking the positive direction as the observation direction, setting the rotation direction, and any positioning point as the starting point, determine the sequence information of multiple positioning points in the source point set (A1…A N ) and the order information of the corresponding angles (α1…α N ), where α1…α N Indicates that it corresponds to the positioning point A1…A N The angle value of

[0010] Taking the positive direction as the viewing direction, setting the rotation direction and each positioning point as the starting point, determining the sequence information of the multiple positioning points in the target point set (B i …B j ) and the order information of the corresponding angles (β i …β j ), where β i …β j Indicates that it corresponds to the positioning point B i …B j The angle value, β i represents the anchor point as the starting point, β j Indicates the last positioning point;

[0011] According to the order information (β i …β j ) and the order information of the angles in the source point set (α1…α N ), from the order information (B i …B j ) in (A1…A N ) to match the order information of a positioning point.

[0012] Optionally, determining the sequence information of the plurality of positioning points in the source point set (A1…A N ) and the order information of the corresponding angles (α1…α N ),include:

[0013] Obtaining coordinates of multiple positioning points in the source point set;

[0014] Calculate the arithmetic mean of the coordinates of multiple positioning points to obtain the centroid C1 and coordinates of the fitting plane of the source point set;

[0015] Determine the connecting line between the centroid C1 and each positioning point in the source point set;

[0016] According to the coordinates of the centroid C1 and the coordinates of each positioning point in the source point set, the angles α1…α between each connecting line and the centroid C1 are calculated. N ;

[0017] According to the sequence information of multiple positioning points in the source point set (A1...A N) determines the order information of the corresponding angles (α1…α N ).

[0018] Optionally, determine the order information (β i …β j ),include:

[0019] Obtaining the world coordinates of multiple positioning points in the target point set;

[0020] Calculate the arithmetic mean of the world coordinates of multiple positioning points to obtain the centroid C2 and world coordinates of the fitting plane of the target point set;

[0021] Determine the connection line between the centroid C2 and each positioning point in the target point set;

[0022] The angle β between each connecting line and the centroid C2 is calculated based on the world coordinates of the centroid C2 and the world coordinates of each positioning point in the target point set. i …β j ;

[0023] According to the sequence information of the plurality of positioning points in the target point set (B i …B j ) determines the order information of the corresponding angle (β i …β j ).

[0024] Optionally, determining the sequence information of the plurality of positioning points in the source point set (A1…A N ) and the order information of the corresponding angles (α1…α N ),include:

[0025] Obtaining coordinates of multiple positioning points in the source point set;

[0026] According to the coordinates of multiple positioning points, the angles α1…α between the lines connecting the positioning points are calculated. N ;

[0027] According to the sequence information of multiple positioning points in the source point set (A1...A N ) determines the order information of the corresponding angles (α1…α N ).

[0028] Optionally, determine the order information (β i …β j ),include:

[0029] Obtaining the world coordinates of multiple positioning points in the target point set;

[0030] Calculate the angle β between the lines connecting each positioning point according to the world coordinates of multiple positioning points i …β j ;

[0031] According to the sequence information of the plurality of positioning points in the target point set (B i …B j ) determines the order information of the corresponding angle (β i …β j ).

[0032] Optionally, determining a same normal vector as a positive direction in the source point set fitting plane and the target point set fitting plane includes:

[0033] Determine an in-vivo point in the three-dimensional coordinate system of the preoperative body surface positioning point image, and then obtain a vector m1 pointing from the in-vivo point to the centroid C1, and determine the one of the two normal vectors of the source point set fitting plane that has a smaller angle with the vector m1 as the positive direction;

[0034] An external point is determined in the three-dimensional coordinate system of the intraoperative body surface positioning point image, and then a vector m2 pointing from the external point to the centroid C2 is obtained, and one of the two normal vectors of the target point set fitting plane that has a larger angle with the vector m2 is determined as the positive direction.

[0035] Optionally, according to the order information (β i …β j ) and the order information of the angles in the source point set (α1…α N ), from the order information (B i …B j ) in (A1…A N ) The sequence information of a matching anchor point includes:

[0036] Calculate the difference between each group of angles in the target point set and the angles in the source point set;

[0037] The order information of the target point set with the smallest difference is used as the N ) to match the order information of a positioning point.

[0038] Optionally, the difference between each group of angles in the target point set and the angles in the source point set is calculated in the following manner:

[0039] Δ i =|β i -α1|+|β i+1 -α2|……|β j -α N |

[0040] Among them, Δ i Represents the difference between the angle in the i-th group of target points and the angle in the source points.

[0041] Optionally, the positive direction is a direction outward from the human body.

[0042] The second aspect of the present invention provides a point set matching device for a body surface positioning band, the device comprising: a processor and a memory connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor executes the above-mentioned point set matching method for the body surface positioning band.

[0043] The present invention obtains source point sets and target point sets by acquiring body surface positioning band images before and during surgery, and through plane fitting and accurate determination of the positive direction of the normal vector, significantly improves the accuracy of point set matching, especially when processing point sets with axial symmetry, effectively avoiding the matching failure problem caused by the inability to distinguish symmetrical points in traditional algorithms. The present invention significantly improves the accuracy of point set matching, thereby improving the precision and safety of surgery and reducing the surgical risks caused by inaccurate positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 is a flow chart of a point set matching method for a body surface positioning belt in an embodiment of the present invention;

[0046] Figure 2 is a positioning point diagram in the body surface positioning belt in an embodiment of the present invention;

[0047] Figure 3 A plane P graph is fitted for the source point set in the embodiment of the present invention;

[0048] Figure 4 A centroid angle diagram of a source point set fitting plane in an embodiment of the present invention;

[0049] Figure 5 A centroid angle diagram of a target point set fitting plane in an embodiment of the present invention;

[0050] Figure 6 is a schematic diagram of determining the positive direction for a preoperative image in an embodiment of the present invention;

[0051] Figure 7 It is a schematic diagram of determining the positive direction for an intraoperative image in an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0054] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0055] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0056] like Figure 1 As shown, an embodiment of the present invention provides a point set matching method for a body surface positioning belt, which is executed by an electronic device such as a computer or a server, and specifically includes:

[0057] S1, obtaining a preoperative body surface positioning point image and an intraoperative body surface positioning point image of a body surface positioning belt attached to the surface of a human body.

[0058] The body surface positioning belt is a convex polygon composed of multiple reflective balls (greater than or equal to 3 balls), and the body surface positioning belt has symmetry. The body surface positioning belt is attached to the designated position of the human body, and a CT image of the body surface positioning belt is taken before surgery to obtain a preoperative body surface positioning point image; during surgery, the body surface positioning belt is photographed using an intraoperative image acquisition device to obtain an intraoperative body surface positioning point image, and the intraoperative image acquisition device can be a binocular camera device.

[0059] S2, identifying a plurality of positioning points in the preoperative body surface positioning point image and the intraoperative body surface positioning point image, respectively, to obtain a source point set and a target point set.

[0060] The CT coordinates of multiple reflective balls (locating points) in the preoperative body surface positioning point image are obtained as a source point set, and the world coordinates of multiple reflective balls (locating points) in the intraoperative body surface positioning point image are obtained as a target point set.

[0061] S3, plane fitting is performed on the source point set and the target point set respectively to obtain the source point set fitting plane and the target point set fitting plane. The plane fitting can be performed using the least square method, normal line and other methods.

[0062] S4, respectively obtain two normal vectors of the two fitting planes, and determine the same normal vector in the source point set fitting plane and the target point set fitting plane as the positive direction.

[0063] Among them, the positive direction is, for example, the direction from the human body to the outside (it can also be the direction from the outside to the human body, as long as the positive directions of the two planes are the same). For example, if the body surface positioning belt is attached to the chest cavity of the human body, then the positive direction is the direction pointing to the outside of the chest cavity.

[0064] Obtain two normal vectors of the source point set fitting plane, which are opposite to the source point set fitting plane. At the same time, obtain two normal vectors of the target point set fitting plane, which are also opposite to the target point set fitting plane. Then determine that the normal vector of the source point set fitting plane (or its reverse direction) is consistent with the normal vector of the target point set fitting plane, and then regard it as the positive direction. Determine the positive direction of the normal vectors of the source point set fitting plane and the target point set fitting plane, which can significantly improve the accuracy of positioning point matching and geometric analysis in the source point set fitting plane and the target point set fitting plane.

[0065] S5, taking the positive direction as the observation direction, setting the rotation direction, and any positioning point as the starting point, determine the sequence information of multiple positioning points in the source point set (A1…A N ) and the order information of the corresponding angles (α1…α N ), where α1…α N Indicates that it corresponds to the positioning point A1…A N The angle value of .

[0066] The rotation direction can be clockwise or counterclockwise, and the starting point can be A1…A N Starting from any one of the positioning points in the source point set, the order information of multiple positioning points (A1…A N ) and the order information of the corresponding angles (α1…α N). For example, if you look down from the top in the positive direction and rotate counterclockwise, starting from the positioning point A1, the order of the positioning points is A1…A N , the corresponding angle sequence information α1…α N .

[0067] S6, taking the positive direction as the viewing direction, setting the rotation direction, each positioning point as the starting point, and determining the sequence information of multiple positioning points in the target point set (B i …B j ) and the order information of the corresponding angles (β i …β j ), where β i …β j Indicates that it corresponds to the positioning point B i …B j The angle value, β i represents the anchor point as the starting point, β j Indicates the last positioning point.

[0068] For example, looking down from the top in the positive direction, rotate counterclockwise to locate point B i Starting from the starting point, the order of the positioning points is B i , B i+1 …B j , the corresponding angle order information β i , β i+1 …β j ; Take the positioning point B j Starting from the starting point, the order of the positioning points is B j , B i , B i+1 ..., the corresponding angle order information β j、 β i , β i+1 …; until each anchor point is used as the starting point and all sequential combinations are obtained.

[0069] S7, according to the order information of each group of angles in the target point set (β i …β j ) and the order information of the angles in the source point set (α1…α N ), from the order information (B i …B j ) in (A1…A N ) to match the sequence information of a positioning point.

[0070] Specifically, take the body surface positioning belt with three reflective balls as an example. Figure 2As shown, the left side is the source point set, the positioning points are A1, A2 and A3, and the right side is the target point set, the positioning points are B1, B2 and B3. Since the source point set and the target point set have axial symmetry, the matching will fail. For example, the correct matching relationship is (A1, B1)(A2, B2)(A3, B3). However, due to the axial symmetry of the point set, two matching results will be obtained: (A1, B1)(A2, B2)(A3, B3) and (A1, B1)(A2, B3)(A3, B2). Therefore, the present invention fits the source point set and the target point set into the source point set fitting plane and the target point set fitting plane, respectively, as shown in FIG. Figure 3 Fit plane P to the source point set, and then obtain the two normal vectors n1 and n2 of the fitted plane. The normal vector of the target point set fitting plane is obtained in the same way as the source point set fitting plane, and obtain the two normal vectors n3 and n4 of the fitted plane. Then determine that the normal vectors that are the same for the two planes are positive directions, such as normal vectors n1 and normal vector n3 are positive directions.

[0071] This embodiment obtains the source point set and the target point set by acquiring the body surface positioning band images before and during the operation, and through plane fitting and accurate determination of the positive direction of the normal vector, the accuracy of point set matching is significantly improved, especially when processing point sets with axial symmetry, effectively avoiding the matching failure problem caused by the inability to distinguish symmetrical points in traditional algorithms. The present invention significantly improves the accuracy of point set matching, thereby improving the accuracy and safety of surgery and reducing the surgical risks caused by inaccurate positioning.

[0072] It should be noted that the isosceles triangle formed by the three positioning points shown in the accompanying drawings is only an example provided to illustrate the concept of the invention. There may be more positioning points in actual applications, and the convex polygons formed by their connecting lines are axially symmetrical figures that can be matched using the embodiments of the present invention.

[0073] Moreover, this scheme is not limited to matching the case where the positioning points form an axisymmetric shape, but can also be applied to matching the positioning points of an asymmetric figure. The only situation where this scheme is not suitable for processing multiple positioning points to form a rotationally symmetrical figure is because in rotationally symmetrical figures such as circles, squares, and crosses, the above-mentioned angles determined according to this scheme may all be the same, making it impossible to distinguish the order of the positioning points.

[0074] In one embodiment, in step S5, the sequence information of multiple positioning points in the source point set (A1...A N ) and the order information of the corresponding angles (α1…α N ), including:

[0075] S51, obtaining coordinates of multiple positioning points in the source point set;

[0076] S52, calculating the arithmetic mean of the coordinates of the multiple positioning points to obtain the centroid C1 and coordinates of the fitting plane of the source point set;

[0077] S53, determining the connecting lines between the centroid C1 and each positioning point in the source point set;

[0078] S54, calculating the angles α1…α between each connecting line and the centroid C1 according to the coordinates of the centroid C1 and the coordinates of each positioning point in the source point set N ;

[0079] S55, according to the sequence information of multiple positioning points in the source point set (A1...A N ) determines the order information of the corresponding angles (α1…α N ).

[0080] Specifically, the centroid C1 of the triangle formed by the three positioning points is calculated according to the coordinates of the positioning points A1, A1, and A3. The centroid C1 is connected to the positioning points A1, A1, and A3 respectively, and the angles between the three connecting lines and the centroid C1 are obtained, such as α1, α2, and α3. Figure 4 As shown. Then observe from the top in the positive direction and rotate counterclockwise, starting from the positioning point A1, the order of the positioning points is (A1, A1, A3), and the corresponding angle order information is (α1, α2, α3). This centroid determination method is suitable for any convex polygon.

[0081] This embodiment determines the centroid by calculating the arithmetic mean of multiple positioning points in the source point set, and then calculates the angle between each positioning point and the line connecting the centroid, and determines the angle order according to the order of the positioning points. The angle between the centroid and the line connecting the positioning points can accurately describe the spatial distribution relationship of each positioning point in the source point set relative to the centroid, so as to eliminate the influence of symmetric points on matching. The determination of this spatial relationship is crucial for the subsequent matching algorithm to improve the accuracy of subsequent positioning point matching.

[0082] Furthermore, in step S6, the order information (β i …β j ), including:

[0083] S61, obtaining the world coordinates of multiple positioning points in the target point set;

[0084] S62, calculating the arithmetic mean of the world coordinates of the multiple positioning points to obtain the centroid C2 and world coordinates of the fitting plane of the target point set;

[0085] S63, determining the connection line between the centroid C2 and each positioning point in the target point set;

[0086] S64, calculating the angle β between each connecting line and the centroid C2 according to the world coordinates of the centroid C2 and the world coordinates of each positioning point in the target point set i …β j ;

[0087] S65, according to the sequence information of the plurality of positioning points in the target point set (B i …B j ) determines the order information of the corresponding angle (β i …β j ).

[0088] Specifically, the centroid C2 of the triangle formed by the three positioning points is calculated according to the coordinates of the positioning points B1, B1, and B3. The centroid C2 is connected to the positioning points B1, B1, and B3 respectively, and the angles between the three connecting lines and the centroid C2 are obtained, such as β1, β2, and β3. Figure 5 As shown. Then observe from the top of the positive direction and rotate counterclockwise, starting from the positioning point B1, the order of the positioning points is (B1, B2, B3), and the corresponding angle order information is (β1, β2, β3); starting from the positioning point B2, the order of the positioning points is (B2, B3, B1), and the corresponding angle order information is (β2, β3, β1); starting from the positioning point B3, the order of the positioning points is (B3, B1, B2), and the corresponding angle order information is (β3, β1, β2).

[0089] This embodiment can more accurately describe the spatial distribution characteristics of the target point set by accurately calculating the angles between each positioning point in the target point set and the centroid line, and determining the order information of these angles, so as to eliminate the influence of symmetric points on matching. This precise description helps to reduce errors in the matching process and improve the accuracy of matching. In the process of determining the angle order information, different positioning points can be selected as starting points as needed to obtain different angle order combinations, support the implementation of multiple matching strategies, and improve the accuracy of matching the target point set with the positioning points in the source point set. In another embodiment, step S5 determines the order information (A1...A N ) and the order information of the corresponding angles (α1…α N ),include:

[0090] Get the coordinates of multiple positioning points in the source point set;

[0091] According to the coordinates of multiple positioning points, the angles α1…α between the lines connecting the positioning points are calculated. N ;

[0092] According to the sequence information of multiple positioning points in the source point set (A1…A N ) determines the order information of the corresponding angles (α1…αN ).

[0093] Specifically, this embodiment directly takes the angle between the lines connecting the positioning points A1, A2, and A3, that is, the angle of the positioning point as the corner point corresponds one-to-one to the positioning point, and calculates the angles α1 (∠A2A1A3), α2 (∠A3A2A1), and α3 (∠A1A3A2) according to the coordinates of the positioning points A1, A2, and A3. Then, observe from the top to the bottom in the positive direction, rotate counterclockwise, and start with the positioning point A1 as the starting point. Then the order of the positioning points is (A1, A1, A3), and the corresponding angle order information is (α1, α2, α3).

[0094] Furthermore, in step S6, the order information (β i …β j ),include:

[0095] Get the world coordinates of multiple positioning points in the target point set;

[0096] Calculate the angle β between the lines connecting each positioning point according to the world coordinates of multiple positioning points i …β j ;

[0097] According to the order information of multiple positioning points in the target point set (B i …B j ) determines the order information of the corresponding angle (β i …β j ).

[0098] Specifically, this embodiment directly takes the angle between the lines connecting the positioning points B1, B2, and B3, and the angle of the positioning point as the corner point corresponds to the positioning point one by one. The angles β1 (∠B2B1B3), β2 (∠B1B2B3), and β3 (∠B2B3B1) are calculated according to the world coordinates of the positioning points B1, B2, and B3, and then observed from the top of the positive direction to the bottom, rotating counterclockwise, starting from the positioning point B1 as the starting point, the order of the positioning points is (B1, B2, B3), and the corresponding angle order information is (β1, β2, β3); starting from the positioning point B2 as the starting point, the order of the positioning points is (B2, B3, B1), and the corresponding angle order information is (β2, β3, β1); starting from the positioning point B3 as the starting point, the order of the positioning points is (B3, B1, B2), and the corresponding angle order information is (β3, β1, β2).

[0099] This embodiment can effectively distinguish symmetrical points with axial symmetry by calculating the angle between the source point set and the positioning points in the target point set and comprehensively considering the order information of the angle, thereby avoiding the mismatching problem caused by symmetrical points during the matching process, and further improving the accuracy of subsequent matching between the target point set and the positioning points in the source point set.

[0100] In one embodiment, in step S4, determining a same normal vector as a positive direction in the source point set fitting plane and the target point set fitting plane specifically includes:

[0101] Determine the in-vivo point in the three-dimensional coordinate system of the preoperative body surface positioning point image, and then obtain the vector m1 pointing from the in-vivo point to the centroid C1, and determine the one of the two normal vectors of the source point set fitting plane that has a smaller angle with the vector m1 as the positive direction;

[0103] like Figure 6 As shown, the three-dimensional coordinate system of the preoperative body surface positioning point image can be specifically a three-dimensional coordinate system established based on the preoperative CT image. This coordinate system corresponds to the space inside the patient's body. Therefore, any point 61 inside the body can be selected in this coordinate system, and the vector m1 from the point to the centroid C1 in the source point set fitting plane is calculated. Then, the directions of the normal vectors n1 and n2 in the source point set fitting plane are compared with the vector m1, and the normal vector with the same direction as the vector m1 is selected as the positive direction (i.e., the outward direction of the human body), as shown in FIG. Figure 6 If the normal vector n1 is in the same direction as the vector m1, then the normal vector n1 is determined to be in the positive direction.

[0104] For the target point set fitting plane, the external point is determined in the three-dimensional coordinate system of the intraoperative body surface positioning point image, and then the vector m2 pointing from the external point to the centroid C2 is obtained. Among the two normal vectors of the target point set fitting plane, the one with a larger angle with the vector m2 is determined as the positive direction.

[0105] like Figure 7 As shown, the three-dimensional coordinate system of the intraoperative body surface positioning point image can be a spatial coordinate system related to the binocular camera device. This coordinate system corresponds to the space outside the patient's body. Therefore, any external point 71 can be selected in this coordinate system, and the vector m2 from the external point 71 to the centroid C2 in the target point set fitting plane is calculated. Then, the normal vectors n3 and n4 in the target point set fitting plane are compared with the vector m2 in direction, and the normal vector with a different direction from the vector m2 is selected as the positive direction (i.e., the direction of the human body outward), as shown in FIG. Figure 7 If the normal vector n3 is in a different direction from the vector m2, the normal vector n3 is determined to be in the positive direction.

[0106] This embodiment takes into account the different positions of the body surface positioning points before and during surgery (the body point before surgery is below the positioning band, and the origin during surgery is above the positioning band) to ensure that the normal vectors of the two fitting planes are consistent and both are in the positive direction, thereby improving the accuracy of the subsequent matching of the target point set with the positioning points in the source point set.

[0107] In one embodiment, in step S7, the order information (βi …β j ) and the order information of the angles in the source point set (α1…α N ), from the order information (B i …B j ) in (A1…A N ) The sequence information of a matching anchor point includes:

[0108] S71, calculating the difference between each group of angles in the target point set and the angles in the source point set;

[0109] S72, taking the sequence information of the target point set with the smallest difference as the sequence information of (A1…A N ) to match the sequence information of a positioning point.

[0110] Furthermore, the difference between each group of angles in the target point set and the angles in the source point set is calculated in the following manner:

[0111] Δ i =|β i -α1|+|β i+1 -α2|……|β j -α N |

[0112] Among them, Δ i Represents the difference between the angles in the i-th group of target points and the angles in the source points.

[0113] Specifically, from the above, we can know that the order information of each angle in the source point set is (α1, α2, α3), and all the order information of each angle in the target point set is (β1, β2, β3), (β2, β3, β1), (β3, β1, β2). Then, the difference between each group of angles in the target point set and the angles in the source point set is calculated as follows:

[0114] Δ1=|β1-α1|+|β2-α2|+|β3-α3|

[0115] Δ2=|β2-α1|+|β3-α2|+|β1-α3|

[0116] Δ3=|β3-α1|+|β1-α2|+|β2-α3|

[0117] Then the target point set with the smallest difference among Δ1, Δ2, and Δ3 is the correct order that matches the sequence information (A1, A2, A3) of multiple positioning points in the source point set. For example, if Δ1 is the smallest, that is, the corresponding correct target point set positioning point sequence information is (B1, B2, B3), then the point set matching result is (A1, B1)(A2, B2)(A3, B3).

[0118] This embodiment can ensure the accuracy of matching by calculating the difference between each group of angles in the target point set and the angles in the source point set, and selecting the combination with the smallest difference as the matching result. This method fully considers the spatial distribution characteristics and angle relationship between the point sets, avoids the errors and uncertainties that may exist in traditional matching methods, and eliminates the influence of symmetrical points on the matching results.

[0119] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0120] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0121] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0122] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0123] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A point set matching method for body surface positioning belt, characterized in that: include: Acquire a preoperative body surface positioning point image and an intraoperative body surface positioning point image of a body surface positioning band attached to the surface of the human body; Respectively identifying a plurality of positioning points in the preoperative body surface positioning point image and the intraoperative body surface positioning point image to obtain a source point set and a target point set; Performing plane fitting on the source point set and the target point set respectively to obtain a source point set fitting plane and a target point set fitting plane; Obtain two normal vectors of two fitting planes respectively, and determine the same normal vector in the source point set fitting plane and the target point set fitting plane as the positive direction; Taking the positive direction as the observation direction, setting the rotation direction, and any positioning point as the starting point, determine the sequence information of multiple positioning points in the source point set (A1…A N ) and the order information of the corresponding angles (α1…α N ), where α1…α N Indicates that it corresponds to the positioning point A1…A N The angle value of Taking the positive direction as the viewing direction, setting the rotation direction and each positioning point as the starting point, determining the sequence information of the multiple positioning points in the target point set (B i …B j ) and the order information of the corresponding angles (β i …β j ), where β i …β j Indicates that it corresponds to the positioning point B i …B j The angle value, β i represents the anchor point as the starting point, β j Indicates the last positioning point; According to the order information (β i …β j ) and the order information of the angles in the source point set (α1…α N ), from the order information (B i …B j ) in (A1…A N ) to match the order information of a positioning point.

2. The method according to claim 1, characterized in that Determine the sequence information of multiple positioning points in the source point set (A1...A N ) and the order information of the corresponding angles (α1…α N ),include: Obtaining coordinates of multiple positioning points in the source point set; Calculate the arithmetic mean of the coordinates of multiple positioning points to obtain the centroid C1 and coordinates of the fitting plane of the source point set; Determine the connecting line between the centroid C1 and each positioning point in the source point set; According to the coordinates of the centroid C1 and the coordinates of each positioning point in the source point set, the angles α1…α between each connecting line and the centroid C1 are calculated. N ; According to the sequence information of multiple positioning points in the source point set (A1...A N ) determines the order information of the corresponding angles (α1…α N ).

3. The method according to claim 2, characterized in that Determine the order information of the corresponding angle (β i …β j ),include: Obtaining the world coordinates of multiple positioning points in the target point set; Calculate the arithmetic mean of the world coordinates of multiple positioning points to obtain the centroid C2 and world coordinates of the fitting plane of the target point set; Determine the connection line between the centroid C2 and each positioning point in the target point set; The angle β between each connecting line and the centroid C2 is calculated based on the world coordinates of the centroid C2 and the world coordinates of each positioning point in the target point set. i …β j ; According to the sequence information of the plurality of positioning points in the target point set (B i …B j ) determines the order information of the corresponding angle (β i …β j ). B 1。 4. The method according to claim 1, characterized in that Determine the sequence information of multiple positioning points in the source point set (A1...A N ) and the order information of the corresponding angles (α1…α N ),include: Obtaining coordinates of multiple positioning points in the source point set; According to the coordinates of multiple positioning points, the angles α1…α between the lines connecting the positioning points are calculated. N ; According to the sequence information of multiple positioning points in the source point set (A1...A N ) determines the order information of the corresponding angles (α1…α N ).

5. The method according to claim 4, characterized in that Determine the order information of the corresponding angle (β i …β j ),include: Obtaining the world coordinates of multiple positioning points in the target point set; Calculate the angle β between the lines connecting each positioning point according to the world coordinates of multiple positioning points i …β j ; According to the sequence information of the plurality of positioning points in the target point set (B i …B j ) determines the order information of the corresponding angle (β i …β j ).

6. The method according to claim 3, characterized in that Determining a same normal vector in the source point set fitting plane and the target point set fitting plane as a positive direction includes: Determine an in-vivo point in the three-dimensional coordinate system of the preoperative body surface positioning point image, and then obtain a vector m1 pointing from the in-vivo point to the centroid C1, and determine the one of the two normal vectors of the source point set fitting plane that has a smaller angle with the vector m1 as the positive direction; An external point is determined in the three-dimensional coordinate system of the intraoperative body surface positioning point image, and then a vector m2 pointing from the external point to the centroid C2 is obtained, and one of the two normal vectors of the target point set fitting plane that has a larger angle with the vector m2 is determined as the positive direction.

7. The method according to claim 1, characterized in that According to the order information (β i …β j ) and the order information of the angles in the source point set (α1…α N ), from the order information (B i …B j ) in (A1…A N ) The sequence information of a matching anchor point includes: Calculate the difference between each group of angles in the target point set and the angles in the source point set; The order information of the target point set with the smallest difference is used as the N ) to match the order information of a positioning point.

8. The method according to claim 7, characterized in that The difference between each group of angles in the target point set and the angles in the source point set is calculated in the following manner: D i =|β i -α1|+|β i+1 -a2|……|b j -a N | Among them, Δ i Represents the difference between the angle in the i-th group of target points and the angle in the source points.

9. The method according to claim 1, characterized in that: The positive direction is the direction outward from the human body.

10. A point set matching device for a body surface positioning belt, characterized in that: include: A processor and a memory connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor executes the point set matching method for a body surface positioning band as described in any one of claims 1-9.

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