Point Set Matching Method and Device for Body Surface Positioning Belt

Abstract

The present invention provides a point set matching method and device for a body surface positioning band, which is applied to the positioning field of medical surgical robots. The method includes: acquiring a preoperative body surface positioning point image and an intraoperative body surface positioning point image; respectively identifying a plurality of positioning points to obtain a source point set and a target point set; respectively 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 obtaining two normal vectors of the two fitting planes, and determining the same one of the normal vectors in the source point set and the target point set fitting planes as the positive direction; determining the order information of a plurality of positioning points in the source point set and the order information of the corresponding angles; determining the order information of a plurality of positioning points in the target point set and the order information of the corresponding angles; and determining, according to the order information of each group of angles in the target point set and the order information of the angles in the source point set, the order information of a positioning point that is matched from the order information. The present invention improves the accuracy of symmetric point set matching.

Description

Technical Field

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

[0002] In the engineering field, the point set (or point cloud) registration technology plays a crucial role. Its core objective is to find a transformation matrix that can accurately overlap the source point set and the target point set. The essence of this process lies in precisely establishing a one-to-one correspondence between the two sets of points, that is, point set matching. The point set matching algorithm, as a mathematical tool for this task, through precise calculations and analyses, endeavors to explore the optimal point set matching scheme to ensure the high precision and reliability of registration.

[0003] The point set matching algorithm has a wide range of applications in multiple fields, especially in the body surface positioning belt of medical surgical robots. In medical practice, a body 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 surgery, the positioning belt is attached to the patient's body for CT scanning, and the CT coordinates of the n small balls can be extracted in the CT image as the source point set; during surgery, the NDI infrared navigation positioning system is responsible for capturing the world coordinates of these small balls to form the target point set. For the precise progress of the surgery, it is necessary to match the coordinates of these two sets of points. However, traditional point set matching algorithms have obvious deficiencies when dealing with certain specific situations. For example, when dealing with point sets with axial symmetry, due to the inability to accurately distinguish symmetric points, traditional algorithms often lead to matching failures, thus affecting the accuracy and safety of the surgery. Summary of the Invention

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

[0005] Obtain preoperative body surface positioning point images and intraoperative body surface positioning point images of the body surface positioning belt attached to the human body surface;

[0006] Identify multiple 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;

[0007] Perform 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 the two fitting planes respectively, and determine the same one of the normal vectors 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 using any fixed point as the starting point, determine the sequence information (A1…A N ) of multiple positioning points in the source point set and the sequence information (α1…α N ) of the corresponding angles, where α1…α N represents the angle values corresponding to the positioning points A1…A N ;

[0010] Taking the positive direction as the observation direction, setting the rotation direction, and using each fixed point as the starting point, determine the sequence information (B i …B j ) of multiple positioning points in the target point set and the sequence information (β i …β j ) of the corresponding angles, where β i …β j represents the angle values corresponding to the positioning points B i …B j , β i represents the positioning point as the starting point, and β j represents the last positioning point;

[0011] According to the sequence information (β i …β j ) of each group of angles in the target point set and the sequence information (α1…α N ) of the angles in the source point set, determine the sequence information of a positioning point that matches (A1…A i …B j ) from the sequence information (B N ).

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

[0013] Obtain the 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] I Determine the connection lines between the centroid C1 and each positioning point in the source point set;

[0016] Calculate the angles α1…α N between each connection 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;

[0017] According to the sequence information (A1…A N) Determine the sequence information of the corresponding angles (α1…α N ).

[0018] Optionally, determine the sequence information of the corresponding angles (β i …β j ), including:

[0019] Obtain 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 of the plane fitted by the target point set and its world coordinates;

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

[0022] Calculate the angles β i …β j between each connection 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;

[0023] Determine the sequence information of the corresponding angles (β i …B j ) according to the sequence information (B i …B j ) of multiple positioning points in the target point set.

[0024] Optionally, determine the sequence information of multiple positioning points (A1…A N ) and the sequence information of the corresponding angles (α1…α N ), including:

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

[0026] Calculate the angles α1…α N between the connections of each positioning point according to the coordinates of multiple positioning points;

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

[0028] Optionally, determine the sequence information of the corresponding angles (β i …β j ), including:

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

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

[0031] According to the sequence 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 ).

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

[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] Calculating the difference between each set 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 ) matches the order information of an anchor point.

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

[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 target point set and the angle in the source point set.

[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, which includes: a processor and a memory connected to the processor; wherein the memory stores instructions that can be executed by the processor, and the instructions are executed by the processor to enable the processor to execute the above-mentioned point set matching method for the body surface positioning band.

[0043] This method acquires source and target point sets by acquiring preoperative and intraoperative body surface positioning band images. Through plane fitting and precise determination of the positive direction of the normal vector, it significantly improves the accuracy of point set matching. This method, particularly when dealing with axisymmetric point sets, effectively avoids the matching failures often associated with traditional algorithms due to their inability to distinguish symmetrical points. This significantly improves the accuracy of point set matching, thereby enhancing surgical precision and safety while reducing surgical risks associated with inaccurate positioning. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

[0049] Figure 5 A centroid angle diagram of a plane fitted with a target point set 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 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 clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0053] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is 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 thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0054] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", "connection" 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 directly connected, or indirectly connected through an intermediate medium, and can also be the communication inside two elements. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0055] In addition, the technical features involved in 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] As Figure 1 shown, an embodiment of the present invention provides a point set matching method for a body surface positioning band. This method is executed by an electronic device such as a computer or a server, and specifically includes:

[0057] S1. Obtain preoperative body surface positioning point images and intraoperative body surface positioning point images of the body surface positioning band that fits the human body surface.

[0058] The body surface positioning band is a convex polygon composed of multiple reflective small balls (at least 3 small balls), and the body surface positioning band has symmetry characteristics. The body surface positioning band is attached to a specified position on the human body. Before the operation, a CT image of the body surface positioning band is taken to obtain preoperative body surface positioning point images; during the operation, an intraoperative image acquisition device is used to take pictures of the body surface positioning band to obtain intraoperative body surface positioning point images. The intraoperative image acquisition device can be a binocular camera device.

[0059] S2. Identify multiple positioning points in the preoperative body surface positioning point image and the intraoperative body surface positioning point image respectively, to obtain the source point set and the target point set.

[0060] Obtain the CT coordinates of multiple reflective spheres (positioning points) in the preoperative body surface positioning point image as the source point set, and obtain the world coordinates of multiple reflective spheres (positioning points) in the intraoperative body surface positioning point image as the target point set.

[0061] S3. Perform plane fitting 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. Methods such as the least squares method and normal vectors can be used for plane fitting.

[0062] S4. Obtain two normal vectors of the two fitting planes respectively, and determine the same one of the normal vectors 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 outwards (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 band is attached to the chest position of the human body, then the positive direction is the direction pointing outside the chest.

[0064] Obtain two normal vectors of the source point set fitting plane. These two normal vectors are opposite with respect to the source point set fitting plane. At the same time, obtain two normal vectors of the target point set fitting plane. These two normal vectors are also opposite with respect to the target point set fitting plane. Then determine that the normal vector (or its reverse direction) of the source point set fitting plane is consistent with the direction of the normal vector of the target point set fitting plane, and then regard it as the positive direction. Determining the positive directions of the normal vectors of the source point set fitting plane and the target point set fitting plane 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 using any positioning point as the starting point, determine the sequence information (A1…A N ) of multiple positioning points in the source point set and the sequence information (α1…α N ) of the corresponding angles, where α1…α N represents the angle values corresponding to the positioning points A1…A N .

[0066] Among them, the rotation direction can be clockwise or counterclockwise, and the starting point can start from any one of the positioning points in A1…A N to determine the sequence information (A1…A N ) of multiple positioning points in the source point set and the sequence information (α1…α N)。For example, when observing from above in the positive direction and rotating counterclockwise starting from the positioning point A1, the order of the positioning points is A1…A N , and the order information of the corresponding angles is α1…α N .

[0067] S6. Taking the positive direction as the viewing direction, setting the rotation direction, and starting from each positioning point, determine the order information (B i …B j ) of multiple positioning points in the target point set and the order information (β i …β j ) of the corresponding angles. Among them, β i …β j represents the angle values corresponding to the positioning points B i …B j , β i represents the positioning point as the starting point, and β j represents the last positioning point.

[0068] For example, when observing from above in the positive direction and rotating counterclockwise starting from the positioning point B i as the starting point, the order of the positioning points is B i , B i+1 …B j , and the order information of the corresponding angles is β i , β i+1 …β j ; starting from the positioning point B j as the starting point, the order of the positioning points is B j , B i , B i+1 …, and the order information of the corresponding angles is β j、 β i , β i+1 …; until each positioning point is used as the starting point to obtain all order combinations.

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

[0070] Specifically, taking the body surface positioning bands of 3 reflective small balls as an example, such as Figure 2As shown in the figure, on the left is the source point set, with the positioning points being A1, A2, and A3, and on the right is the target point set, with the positioning points being B1, B2, and B3. Due to the axial symmetry between the source point set and the target point set, it will lead to matching failure. 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 (A1, B1)(A2, B2)(A3, B3) and (A1, B1)(A2, B3)(A3, B2) will be obtained. Therefore, in the present invention, the source point set and the target point set are respectively fitted into the source point set fitting plane and the target point set fitting plane, as Figure 3 is the source point set fitting plane P. Then, two normal vectors n1 and n2 of this fitting plane are obtained. The method for obtaining the normal vectors of the target point set fitting plane is the same as that of the source point set fitting plane, and two normal vectors n3 and n4 of this fitting plane are obtained. Then, the same normal vectors of the two planes are determined as the positive direction. For example, the normal vector n1 and the normal vector n3 are the positive direction.

[0071] In this embodiment, by obtaining the images of the preoperative and intraoperative body surface positioning bands, the source point set and the target point set are obtained, 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 dealing with point sets with axial symmetry, it effectively avoids the matching failure problem caused by the traditional algorithm's inability to distinguish symmetric points. The present invention significantly improves the accuracy of point set matching, thereby improving the precision and safety of the 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 attached figure is only an example provided to illustrate the inventive concept. In actual applications, there can be more positioning points, and as long as the convex polygon formed by their connections is an axially symmetric figure, the embodiments of the present invention can be applied for matching.

[0073] Moreover, this solution is not limited to matching the case where the positioning points form an axially symmetric shape, but can also be applied to matching the positioning points of an asymmetric figure. This solution is only not applicable to dealing with the situation where multiple positioning points form a rotationally symmetric figure. Because in rotationally symmetric figures such as circles, squares, and crosses, all the above-mentioned included angles determined according to this solution may be the same, thus making it impossible to distinguish the order of the positioning points.

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

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

[0076] S52. Calculate the arithmetic mean of the coordinates of multiple positioning points to obtain the centroid C1 of the fitting plane of the source point set and its coordinates.

[0077] S53. Determine the connections between the centroid C1 and each positioning point in the source point set.

[0078] S54. Calculate the angles α1…α between each connection and the centroid C1 based on the coordinates of the centroid C1 and each positioning point in the source point set. N ;

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

[0080] Specifically, first calculate the centroid C1 of the triangle formed by the three positioning points according to the coordinates of the positioning points A1, A1, and A3. Connect the centroid C1 with the positioning points A1, A1, and A3 respectively, and three angles between the connections and the centroid C1 will be obtained, such as α1, α2, and α3, as specifically shown in Figure 4 . Then, observe from above 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 order information of the corresponding angles is (α1, α2, α3). This method of determining the centroid is suitable for any convex polygon.

[0081] In this embodiment, the centroid is determined by calculating the arithmetic mean of multiple positioning points in the source point set. Then, the angles between the connections of each positioning point and the centroid are calculated, and the angle order is determined according to the positioning point order. The angles between the connections of the centroid and 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 point pairs 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, determining the order information (β i …β j ) of the corresponding angles specifically includes:

[0083] S61. Obtain the world coordinates of multiple positioning points in the target point set.

[0084] S62. Calculate the arithmetic mean of the world coordinates of multiple positioning points to obtain the centroid C2 of the fitting plane of the target point set and its world coordinates.

[0085] S63. Determine the connections between the centroid C2 and each positioning point in the target point set.

[0086] S64. Calculate the angle β between each connecting line and the centroid C2 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 ;

[0087] S65. Determine the order information (β i …β j ) of the corresponding angles according to the order information (B i …B j ) of multiple positioning points in the target point set.

[0088] Specifically, first calculate the centroid C2 of the triangle formed by the three positioning points according to the coordinates of the positioning points B1, B1, and B3. Connect the centroid C2 with the positioning points B1, B1, and B3 respectively, and three angles between the connecting lines and the centroid C2 will be obtained, such as β1, β2, β3, as specifically shown in Figure 5 . Then, observe from the upper part in the positive direction and rotate counterclockwise. Starting from the positioning point B1, the order of the positioning points is (B1, B2, B3), and the order information of the corresponding angles is (β1, β2, β3); starting from the positioning point B2, the order of the positioning points is (B2, B3, B1), and the order information of the corresponding angles is (β2, β3, β1); starting from the positioning point B3, the order of the positioning points is (B3, B1, B2), and the order information of the corresponding angles is (β3, β, β2).

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

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

[0091] Calculate the angles α1…α between the connecting lines of each positioning point according to the coordinates of the multiple positioning points. N ;

[0092] Determine the order information (α1…α of the corresponding angles according to the order information (A1…A N ) of multiple positioning points in the source point set.N )。

[0093] Specifically, in this embodiment, the included angles between the connecting lines of the positioning points A1, A2, and A3 are directly taken. That is, the angles with the positioning points as the corner points correspond one-to-one with the positioning points. According to the coordinates of the positioning points A1, A2, and A3, each included angle α1 (∠A2A1A3), α2 (∠A3A2A1), and α3 (∠A1A3A2) is calculated. Then, observing from above the positive direction downward and rotating counterclockwise, starting from the positioning point A1, the order of the positioning points is (A1, A2, A3), and the order information of the corresponding angles is (α1, α2, α3).

[0094] Further, in step S6, determining the order information of the corresponding angles (β i …β j ) includes:

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

[0096] Calculating the included angles β i …β j ;

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

[0098] Specifically, in this embodiment, the included angles between the connecting lines of the positioning points B1, B2, and B3 are directly taken. The angles with the positioning points as the corner points correspond one-to-one with the positioning points. According to the world coordinates of the positioning points B1, B2, and B3, each included angle β1 (∠B2B1B3), β2 (∠B1B2B3), and β3 (∠B2B3B1) is calculated. Then, observing from above the positive direction downward and rotating counterclockwise, starting from the positioning point B1, the order of the positioning points is (B1, B2, B3), and the order information of the corresponding angles is (β1, β2, β3); starting from the positioning point B2, the order of the positioning points is (B2, B3, B1), and the order information of the corresponding angles is (β2, β3, β1); starting from the positioning point B3, the order of the positioning points is (B3, B1, B2), and the order information of the corresponding angles is (β3, β1, β2).

[0099] In this embodiment, by calculating the included angles between the positioning points in the source point set and the target point set and comprehensively considering the order information of the angles, the symmetric points with axial symmetry can be effectively distinguished, thus avoiding the problem of incorrect matching caused by symmetric points during the matching process, and further improving the accuracy of the subsequent matching of the positioning points in the target point set and the source point set.

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

[0101] 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 from the in-vivo point pointing to the centroid C1, and determine the normal vector with a smaller included angle with the vector m1 among the two normal vectors of the source point set fitting plane as the positive direction;

[0102] As Figure 6 shown, the three-dimensional coordinate system of the preoperative body surface positioning point image can specifically be 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, an in-vivo point 61 can be arbitrarily selected in this coordinate system, calculate the vector m1 from this point to the centroid C1 in the source point set fitting plane, and then compare the directions of the normal vectors n1 and n2 in the source point set fitting plane with the vector m1, and select the normal vector in the same direction as the vector m1 as the positive direction (that is, the direction outward from the human body). As Figure 6 shown in

[0103] For the target point set fitting plane, determine an out-of-vivo point in the three-dimensional coordinate system of the intraoperative body surface positioning point image, and then obtain a vector m2 from the out-of-vivo point pointing to the centroid C2, and determine the normal vector with a larger included angle with the vector m2 among the two normal vectors of the target point set fitting plane as the positive direction.

[0104] As Figure 7 shown, the three-dimensional coordinate system of the intraoperative body surface positioning point image can be a space coordinate system related to the binocular camera device. This coordinate system corresponds to the space outside the patient's body. Therefore, an out-of-vivo point 71 can be selected arbitrarily in this coordinate system, calculate the vector m2 from the out-of-vivo point 71 to the centroid C2 in the target point set fitting plane, and then compare the directions of the normal vectors n3 and n4 in the target point set fitting plane with the vector m2, and select the normal vector in a different direction from the vector m2 as the positive direction (that is, the direction outward from the human body). As Figure 7 shown in

[0105] This embodiment takes into account the different positions of the preoperative and intraoperative body surface positioning points (the preoperative in-vivo point is below the positioning band, and the intraoperative origin 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 positioning points in the target point set and the source point set.

[0106] In one embodiment, in step S7, according to the order information of each group of angles in the target point set (β i …βj ) and the order information of the angles in the source point set (α1…α N ), determine the order information of a positioning point that matches (A1…A i …B j ) from the order information (B N ), including:

[0107] S71, calculate the difference between each group of angles in the target point set and the angles in the source point set;

[0108] S72, take the order information of the target point set with the smallest difference as the order information of a positioning point that matches (A1…A N ).

[0109] Furthermore, use the following method to calculate the difference between each group of angles in the target point set and the angles in the source point set:

[0110] Δ i =|β i -α1|+|β i+1 -α2|……|β j -α N |

[0111] where, Δ i represents the difference between the angles in the i-th group of the target point set and the angles in the source point set.

[0112] Specifically, as can be seen from the above, 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 differences between each group of angles in the target point set and the angles in the source point set are specifically:

[0113] Δ1 = |β1 - α1| + |β2 - α2| + |β3 - α3|

[0114] Δ2 = |β2 - α1| + |β3 - α2| + |β1 - α3|

[0115] Δ3 = |β3 - α1| + |β1 - α2| + |β2 - α3|

[0116] Then, the target point set corresponding to the smallest difference among Δ1, Δ2, and Δ3 is the correct order that matches the order information of multiple positioning points (A1, A2, A3) in the source point set. For example, if Δ1 is the smallest, that is, the order information of the positioning points of the corresponding correct target point set is (B1, B2, B3), then the point set matching result is (A1, B1)(A2, B2)(A3, B3).

[0117] In this embodiment, by calculating the differences between the angles of each group 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, the accuracy of the matching can be ensured. This method fully considers the spatial distribution characteristics and angular relationships between the point sets, avoids the errors and uncertainties that may exist in traditional matching methods, and eliminates the influence of symmetric points on the matching result.

[0118] Those skilled in the art should understand that the embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program code.

[0119] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the 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 the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0120] These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured product including an instruction device, and the instruction device implements the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0121] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0122] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill 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 enumerate all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A point set matching method for body surface positioning belt, characterized in that: include: Acquire preoperative and intraoperative body surface positioning point images of a body surface positioning band adhered to the human body surface; 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; 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 the 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 With the positive direction as the viewing direction, set the rotation direction and each positioning point as the starting point, and determine the order 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 anchor 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 ) matches the order information of an anchor 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 lines 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 multiple positioning points in the target point set (B i …B j ) determines the order information of the corresponding angle (β i …β j ).

4. The method according to claim 1, wherein 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 angles α1…α between the lines connecting the multiple positioning points according to the coordinates of the multiple positioning points 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 the multiple positioning points based on the world coordinates of the multiple positioning points i …β j ; According to the sequence 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 ).

6. The method according to claim 3, characterized in that Determining a common 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. 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.

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: Calculating the difference between each set 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 ) matches the order information of an anchor point.

8. The method according to claim 7, characterized in that The difference between each set of angles in the target point set and the angles in the source point set is calculated using the following method: , in, represents the difference between the angle in the i-th target point set and the angle in the source point set.

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 that can be executed by the processor, and the instructions are executed by the processor to enable the processor to perform the point set matching method for a body surface positioning belt as described in any one of claims 1-9.

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