Incomplete square identification method and system and auxiliary positioning method and device

Abstract

The invention relates to the technical field of vision measurement, and provides an incomplete square identification method and system, and an auxiliary positioning method and device, and the identification method comprises the steps: obtaining an image of an incomplete square in a view field, and carrying out the adaptive binarization of the image; extracting all closed contours from the binarized image; reserving the contour meeting the first picture size proportion relation; the first picture size proportion relation is that the total length of the contour lines is between 0.03 times the larger value of the width and the height of the image and 4 times the larger value of the width and the height of the image; an incomplete square convex polygon contour needing to be recognized is reserved; finding out at least two vertexes which are not on the edge of the picture; supplementing the vertexes of the square according to the at least two vertexes; and constructing a complete square according to the top points of the supplemented square. According to the scheme, visual positioning can be carried out, the calculation method is simple, and more position information of the unmanned aerial vehicle can be obtained.

Description

Technical Field

[0001] The present invention relates to the field of visual measurement technology, and in particular to an incomplete square recognition method and system, and an auxiliary positioning method and device. Background Art

[0002] As drone applications in the industry become increasingly diversified, facing complex and harsh operating environments, reliability and intelligence have become important factors in measuring the maturity of drone systems. As part of the intelligent application of air-based robots, the drone vision-assisted positioning method can effectively avoid position offsets caused by unreliable satellite navigation signals in certain application scenarios.

[0003] The existing CN110989687A proposes to use a multi-layer square pattern with overlapping centers to guide the drone to land; this method has strict requirements on the pattern and can only be used for altitude calculation. The obtained position information is too little, which is not conducive to the intelligent application of aircraft.

[0004] In addition, when the drone is landing, it will get closer and closer to the square pattern, and may not be able to capture the entire pattern, resulting in the inability to locate it.

[0005] Therefore, it is necessary to provide an incomplete square recognition method and system, an auxiliary positioning method and device, which can perform visual positioning, have a simple solution method, and can obtain more drone location information.

[0006] The above information disclosed in the Background section is only for enhancement of understanding of the background of the present application and therefore it may contain information that does not constitute the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0007] The main purpose of the present invention is to overcome the problem of inability to locate or inaccurate positioning of a UAV when landing, and to provide an incomplete square recognition method and system, an auxiliary positioning method and device, which can perform visual positioning, have a simple solution method, and can obtain more UAV location information.

[0008] To achieve the above-mentioned purpose, the first aspect of the present invention provides a method for identifying an incomplete square in a field of view, where the square has a different color from its background, comprising the following steps: Acquire an incomplete square image within the field of view and perform adaptive binarization of the image; Extract all closed contours in the binary image; Retaining contours that satisfy a first screen size ratio relationship and whose contours and vertices cannot form a complete square; the first screen size ratio relationship is that the total length of the contour line is between 0.03 times the larger value of the width and height of the image and 4 times the larger value of the width and height of the image; Keep the convex polygon outline of the incomplete square that needs to be recognized; Find at least two vertices that are not on the edge of the picture; Fill in the vertices of the square based on at least two vertices; Construct a complete square from the vertices of the completed square.

[0009] According to an exemplary embodiment of the present invention, finding at least two vertices that are not on the edge of the screen includes: According to the convex polygonal outline of the incomplete square to be identified, the total number of vertices is obtained to be 4, 5 or 6; if the number of vertices is 4 or 6, two vertices that are not on the edge of the picture are found; if the number of vertices is 5, three vertices that are not on the edge of the picture are found.

[0010] According to an exemplary embodiment of the present invention, the step of filling in the vertices of a square according to at least two vertices comprises: If the total number of vertices is 4, construct two squares based on the two vertices that are not at the edge of the picture to form two groups of candidate third vertices and fourth vertices, and retain the candidate third vertices and fourth vertices on the same side of the line connecting the two vertices at the edge of the picture as the third vertex and fourth vertex of the incomplete square; If the total number of vertices is 5, three parallelograms are constructed based on the three vertices that are not on the edge of the screen to form three candidate fourth vertices, and the candidate fourth vertices whose intersecting line lengths satisfy the first predetermined ratio and whose sequential line lengths satisfy the second predetermined ratio are retained as the fourth vertices of the incomplete square; If the number of vertices is 6 in total, a square is constructed based on two vertices that are not on the edge of the picture, forming a third vertex and a fourth vertex.

[0011] As a second aspect of the present invention, the present invention provides a recognition system for an incomplete square in a field of view, comprising a contour extraction module, a vertex completion module and a square construction module connected in sequence; The contour extraction module is used to obtain an image of an incomplete square in the field of view, and adaptively binarize the image; extract all closed contours in the binarized image; retain contours that meet the first picture size ratio relationship; and retain the convex polygonal contour of the incomplete square that needs to be identified; The vertex completion module is used to find at least two vertices that are not on the edge of the picture; and complete the vertices of the square according to the at least two vertices; The square construction module is used to construct a complete square according to the vertices of the padded square.

[0012] As a third aspect of the present invention, the present invention provides an auxiliary positioning method for aircraft landing, comprising the following steps: S1: Set the nested mark on the ground and obtain the world coordinates of each vertex of each square; The nested mark includes n squares, the nth square is nested in the n-1th square, n is a natural number greater than or equal to 2, and the centers of the nth square and the n-1th square are not in the same position; S2: Continuously photograph the nesting mark from a landing aircraft located above the nesting mark, and the camera focal length remains unchanged during the photographing process; S3: identifying squares in sequence starting from the first square, and if the largest square in the field of view is incomplete, using the method for identifying an incomplete square in the field of view to identify the square; S4: Obtain the position of the aircraft according to the image coordinates and world coordinates of each vertex corresponding to the found n-1th square and the nth square, wherein the nth square has at least two vertices in the shooting picture.

[0013] According to an exemplary embodiment of the present invention, in step S1, in the nested mark, the two nested squares of similar sizes have different colors, or the two nested squares of similar sizes have the same color and there is an isolation figure of different color and not a square nested with the two squares of similar sizes.

[0014] According to an exemplary embodiment of the present invention, in step S4, obtaining the position of the aircraft according to the image coordinates and world coordinates of each vertex corresponding to the found n-1th square and the nth square includes: Get the direction of the camera based on the positional relationship between the n-1th square and the nth square; According to the direction of the camera, order the four vertices of the n-1th square; According to the order of the four vertices, the pose relationship between the world coordinate system and the image coordinate system of the four vertices is matched through PnP solution to obtain the relative displacement transformation matrix; The position information of the aircraft is obtained according to the relative displacement transformation matrix.

[0015] According to an exemplary embodiment of the present invention, obtaining the direction of the camera according to the positional relationship between the n-1th square and the nth square includes: Project the vertices of the two squares to the standard square; The relative positions of the two squares are matched with the template of the nested logo to get the camera's pointing direction.

[0016] According to a fourth aspect of the present invention, the present invention provides an auxiliary positioning device for aircraft landing, comprising: a nested marker, a camera, a recognition system for the incomplete square in the field of view, and a position solving module; The nested mark is set on the ground; the nested mark includes n squares, the nth square is nested in the n-1th square, n is a natural number greater than or equal to 2, and the centers of the nth square and the n-1th square are not in the same position; The camera is set on the aircraft, and the nesting mark is continuously photographed from the aircraft that is located above the nesting mark and is landing. The focal length of the camera does not change during the photographing process; The position solution module is used to obtain the world coordinates of each vertex of each square; starting from the first square, the squares are identified in sequence. If the largest square in the field of view is incomplete, the incomplete square recognition system in the field of view is used to identify the square; the position of the aircraft is obtained according to the image coordinates and world coordinates of each vertex corresponding to the found n-1th square and the nth square, wherein the nth square has at least 2 vertices in the shooting picture.

[0017] The advantages of the present invention are: The present invention proposes a new eccentric asymmetric square mark, which has multiple squares with different positional relationships and proportional relationships. The position of the aircraft can be identified and located in three situations: combination, nesting and partial loss. It can cover operating conditions such as aircraft cruising, take-off and landing, and incomplete mark abnormalities, and can identify incomplete squares, thereby expanding the scope of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present application will become more apparent by describing in detail the exemplary embodiments thereof with reference to the accompanying drawings. The accompanying drawings described below are only some embodiments of the present application, and it is clear to a person skilled in the art that other accompanying drawings can be obtained from these accompanying drawings without creative effort.

[0019] Figure 1 A schematic diagram of a first type of nested flag is shown schematically.

[0020] Figure 2 A schematic diagram of the second type of nested flag is schematically shown.

[0021] Figure 3 A schematic diagram schematically shows the vertices of a square identifying a positioning mark of a first type of aircraft.

[0022] Figure 4 A schematic diagram schematically shows the vertices of a square identifying a positioning mark of a second type of aircraft.

[0023] Figure 5 The figure schematically shows the steps of a method for assisting the positioning of an aircraft landing.

[0024] Figure 6A schematic diagram for identifying the vertices of a first type of incomplete square is schematically shown.

[0025] Figure 7 A schematic diagram for identifying vertices of a second incomplete square is schematically shown.

[0026] Figure 8 A schematic diagram for identifying vertices of a third type of incomplete square is schematically shown.

[0027] Fig. 9 The four directions of the nested logo are schematically shown.

[0028] Fig.10 The figure schematically shows a real shot of a nested logo taken by an aircraft.

[0029] Fig.11 The figure schematically shows a real shot of a nested logo taken by an aircraft (another situation). DETAILED DESCRIPTION

[0030] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0031] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0032] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0033] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0034] It should be understood that although the terms first, second, third, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one component from another component. Therefore, the first component discussed below can be referred to as the second component without departing from the teachings of the concepts of the present application. As used herein, the term "and / or" includes any one of the associated listed items and all combinations of one or more.

[0035] Those skilled in the art will appreciate that the drawings are merely schematic diagrams of example embodiments, and the modules or processes in the drawings are not necessarily necessary for implementing the present application, and therefore cannot be used to limit the scope of protection of the present application.

[0036] According to a first specific embodiment of the present invention, the present invention provides an auxiliary positioning device for aircraft landing, including: a nested marker, a camera, a recognition system for incomplete squares in the field of view, and a position solving module.

[0037] The nested mark is set on the ground; the nested mark includes n squares, the nth square is nested in the n-1th square, n is a natural number greater than or equal to 2, and the centers of the nth square and the n-1th square are not in the same position. The recognized figure is a square, which is easy to recognize, because the square has the characteristics of equal length of four sides and diagonals, while the rectangular feature is relatively unclear and easy to misdetect, especially when observed at an inclined angle. Similarly, for example, the mark points are mostly used in perfect circles instead of ellipses.

[0038] In the nested logo, two nested squares of similar size have different colors, or two nested squares of similar size have the same color and there is an isolation figure of different color and not a square nested with the two similar size squares.

[0039] The ratio of the side lengths of the n-1th square to the nth square is (3-6):1. Figure 1 As shown, Figure 1 This is the positioning mark of the first case. The first square is a black square, and the second square is a white square. The second square is nested in the first square, and the center of the second square is not in the same position as the center of the first square. The two are combined into an eccentric asymmetric square. Figure 3 The vertices of the marked squares can be clearly seen. Figure 2 As shown, Figure 2 For the positioning mark of the second case, the first square is a large black square, the isolation figure is a white rectangle, and the second square is a small black square. Figure 4The vertices of the marked squares can be clearly seen. The isolation pattern is nested inside the first square, and the second square is nested inside the isolation pattern. The reason why the two squares are made of different colors or the isolation pattern is set in the middle is to be able to clearly identify the sides and vertices of the squares.

[0040] The camera is set on the aircraft, and the nesting mark is continuously photographed from the aircraft that is landing above the nesting mark. The camera focal length does not change during the shooting process. The position calculation of auxiliary positioning requires real-time lens focal length information, and fixed focus is used to facilitate position calculation during flight.

[0041] A recognition system for an incomplete square in a field of view includes a contour extraction module, a vertex completion module, and a square construction module connected in sequence. The contour extraction module is used to obtain an image of an incomplete square in the field of view, and the image is adaptively binarized; all closed contours are extracted from the binarized image; contours that satisfy the first screen size ratio relationship are retained; and the convex polygonal contour of the incomplete square to be recognized is retained. The vertex completion module is used to find at least two vertices that are not at the edge of the screen; and the vertices of the square are completed according to the at least two vertices. The square construction module is used to construct a complete square according to the vertices of the completed square.

[0042] The position calculation module is used to obtain the world coordinates of each vertex of each square; the squares are identified in sequence starting from the first square. If the largest square in the field of view is incomplete, the recognition system of incomplete squares in the field of view is used to identify the square; the position of the aircraft is obtained based on the image coordinates and world coordinates of each vertex corresponding to the found n-1th square and the nth square, where the nth square has at least 2 vertices in the shooting screen.

[0043] According to a second specific embodiment of the present invention, the present invention provides an auxiliary positioning method for an aircraft landing, using the auxiliary positioning device for an aircraft landing of the first specific embodiment, such as Figure 5 As shown, the following steps are included: S1: Set the nested mark on the ground and obtain the world coordinates of each vertex of each square.

[0044] The nested mark includes n squares, the nth square is nested in the n-1th square, n is a natural number greater than or equal to 2, and the centers of the nth square and the n-1th square are not in the same position.

[0045] In the nested logo, two nested squares of similar size have different colors, or two nested squares of similar size have the same color and there is an isolation figure of different color and not a square nested with the two similar size squares.

[0046] S2: The nesting mark is continuously photographed from a landing aircraft located above the nesting mark, and the camera focal length remains unchanged during the photographing process.

[0047] S3: Starting from the first square, identify the squares one by one. If the largest square in the field of view is incomplete, use the method for identifying incomplete squares in the field of view to identify the squares.

[0048] A method for identifying an incomplete square in a field of view, the square being different in color from its background, comprises the following steps: S31: Acquire an incomplete square image in the field of view, and adaptively binarize the image.

[0049] S32: Extract all closed contours in the binary image.

[0050] S33: retaining the outline that satisfies the first screen size ratio relationship and the outline and the vertices cannot form a complete square.

[0051] The first picture size ratio is that the total length of the contour line is between 0.03 times the larger value of the width and height of the image and 4 times the larger value of the width and height of the image; 0.03×max(w, h)≤total length of contour line≤4×max(w, h), where w represents the image width and h represents the image height; squares that are too large or too small in the picture will not be recognized to avoid false detection.

[0052] The incomplete square is caused by the field of view problem. It appears because the square mark falls on the edge of the picture. Through filtering, we can prevent the detection of irrelevant squares in the picture. Because too many irrelevant squares need to be excluded, they will affect the calculation efficiency.

[0053] The combination of vertex and contour features can be considered as an incomplete square.

[0054] S34: retain the convex polygon outline of the incomplete square that needs to be identified.

[0055] S35: Find at least two vertices that are not on the edge of the picture.

[0056] Finding at least two vertices that are not on the edge of the picture involves: According to the convex polygonal outline of the incomplete square to be identified, the total number of vertices is obtained to be 4, 5 or 6; if the number of vertices is 4 or 6, two vertices that are not on the edge of the picture are found; if the number of vertices is 5, three vertices that are not on the edge of the picture are found.

[0057] S36: Fill in the vertices of the square according to at least two vertices.

[0058] The vertices to complete the square based on at least two vertices include: like Figure 6 As shown, if the total number of vertices is 4, two squares are constructed based on the two vertices that are not at the edge of the picture, forming two groups of candidate third vertices and fourth vertices, and the candidate third vertices and fourth vertices on the same side of the line connecting the two vertices at the edge of the picture are retained as the third vertex and fourth vertex of the incomplete square. Figure 6 It is a 2V1E structure, that is, it has only 2 vertices and 1 complete edge. Figure 6 The four points in the middle are two groups of candidate third vertices and fourth vertices. The solid dots at the top are taken as the third and fourth vertices, and the hollow dots at the bottom are excluded.

[0059] like Figure 7 As shown, if the total number of vertices is 5, three parallelograms are constructed based on the three vertices that are not on the edge of the screen to form three candidate fourth vertices, and the candidate fourth vertices whose cross-connection lengths between vertices satisfy the first predetermined ratio and whose sequential connection lengths between vertices satisfy the second predetermined ratio are retained as the fourth vertices of the incomplete square. The parallelogram is used because it is more convenient to use parallel lines instead of points and angles to establish a parallelogram in engineering. As a preferred embodiment, a square or rectangle is constructed based on three vertices that are not on the edge of the screen. Figure 7 It is a 3V2E structure, that is, it has only 3 vertices and 2 complete edges. Figure 7 The three points in the middle are the candidate fourth vertices, the solid dot at the top is the fourth vertex, and the other hollow dots are excluded. The first predetermined proportional relationship: the length ratio of the intersection line X / Y is between 0.5-2, so that rhombuses will not be misdetected. X and Y represent two intersection lines respectively. The second predetermined proportional relationship: the length of each sequential connection line A / B / C / D of the vertices must account for more than 20% of the total length of A+B+C+D, so that irregular quadrilaterals will not be misdetected. A, B, C, and D represent four vertices respectively.

[0060] like Figure 8 As shown, if the total number of vertices is 6, a square is constructed based on two vertices that are not on the edge of the screen, forming the third vertex and the fourth vertex. Figure 8 It is a 2V0E structure, that is, it has only 2 vertices and 0 complete edges. Figure 8 The two solid dots in the middle are the third and fourth vertices.

[0061] S37: Construct a complete square based on the vertices of the completed square.

[0062] S4: Obtain the position of the aircraft according to the image coordinates and world coordinates of each vertex corresponding to the found n-1th square and the nth square, wherein the nth square has at least two vertices in the shooting picture.

[0063] The position of the aircraft is obtained based on the image coordinates of each vertex corresponding to the found n-1th square and the nth square and the world coordinates, including: S41: Obtain the direction of the camera according to the positional relationship between the n-1th square and the nth square.

[0064] The camera's orientation is obtained based on the positional relationship between the n-1th square and the nth square: S411: Project each vertex of the two squares to a standard square; S412: Match the relative positions of the two squares with the template of the nested logo to obtain the direction of the camera.

[0065] The positional relationship that needs to be confirmed is the positional relationship between the n-1th square and the nth square.

[0066] The connection between each vertex is a processing step in the subsequent recognition process. Recognition has always been implemented based on four vertices. It is necessary to determine whether the four vertices are the four vertices of a square. The length information of the total four lines connecting two adjacent vertices is needed for judgment. The template of the nested mark is defined as a standard pointing diagram, and the template of the aircraft's positioning mark is matched according to the relationship between the side length and the diagonal line. After the picture is rotated, it is easy to identify the change in pointing according to the relative relationship between the inner and outer squares.

[0067] like Fig. 9 As shown, Fig. 9 for Figure 1 Schematic diagram of the positioning marks in the four directions. Figure 1 In the figure, the second square is close to the upper edge of the first square. The camera direction at this time is defined as pointing upward. Fig. 9 (a) The camera points upward. Fig. 9 (b) The camera points to the right. Fig. 9 (c) The camera points downward. Fig. 9 (d) The camera is pointing to the left. The advantage of an off-center square is that you can tell which direction the camera is pointing in the picture.

[0068] S42: Order the four vertices of the n-1th square according to the direction of the camera.

[0069] The four sequenced points are #0, #1, #2, and #3.

[0070] The ordering is based on the template of the nested flags, such as Figure 3As shown, the vertex of the upper left corner of the first square is #0, the vertex of the upper right corner is #1, the vertex of the lower right corner is #2, and the vertex of the lower left corner is #3; the vertex of the upper left corner of the second square is #0, the vertex of the upper right corner is #1, the vertex of the lower right corner is #2, and the vertex of the lower left corner is #3. Similarly, Figure 4 In the figure, the vertex of the upper left corner of the first square is #0, the vertex of the upper right corner is #1, the vertex of the lower right corner is #2, and the vertex of the lower left corner is #3; the vertex of the upper left corner of the second square is #0, the vertex of the upper right corner is #1, the vertex of the lower right corner is #2, and the vertex of the lower left corner is #3; the vertex of the upper left corner of the third square is #0, the vertex of the upper right corner is #1, the vertex of the lower right corner is #2, and the vertex of the lower left corner is #3.

[0071] Fig.10 for Figure 1 The second square (white square) is on the upper side, so we know that the camera is pointing upwards at this time), and the point where the first square (black square) is located to the left of the white square is identified as 17#0. Numbering them clockwise, the remaining corners are 17#1, 17#2, and 17#3. Fig.11 for Figure 1 Another real shot of the positioning mark, Figure 10 to Figure 11 , the positioning marks are from far to near and rotated. The second square (white square) is on the upper side, so we know that the camera is pointing upward at this time. The point where the first square (black square) is located above the white square is 17#0. Numbered clockwise, the remaining corners are 17#1, 17#2, and 17#3.

[0072] S43: According to the order of the four vertices, the pose relationship between the world coordinate system and the image coordinate system of the four vertices is matched by PnP solution to obtain a relative displacement transformation matrix.

[0073] In the camera image, the 2D coordinates of the square vertices on the image are directly or indirectly extracted, and the pose relationship between the 3D world coordinates and the 2D image coordinates is matched through PnP solution to obtain the relative displacement transformation matrix R / T, where R is the rotation matrix and T is the translation vector.

[0074] S44: Obtain the position information of the aircraft according to the relative displacement transformation matrix.

[0075] This scheme proposes a new eccentric asymmetric square mark, which has multiple squares with different positional relationships and proportional relationships. It can identify and locate the position of the aircraft in three situations: combination, nesting and partial loss. It can cover operating conditions such as aircraft cruising, take-off and landing, and incomplete marking abnormalities, and can identify incomplete squares, expanding the scope of use.

[0076] The exemplary embodiments of the present invention are specifically shown and described above. It should be understood that the present invention is not limited to the detailed structure, configuration or implementation method described herein; on the contrary, the present invention is intended to cover various modifications and equivalent configurations included in the spirit and scope of the appended claims.

Claims

1. A method for identifying an incomplete square in a field of view, wherein the square is different in color from its background, characterized in that: The following steps are involved: Acquire an incomplete square image within the field of view and perform adaptive binarization of the image; Extract all closed contours in the binary image; Retaining contours that satisfy a first screen size ratio relationship and whose contours and vertices cannot form a complete square; the first screen size ratio relationship is that the total length of the contour line is between 0.03 times the larger value of the width and height of the image and 4 times the larger value of the width and height of the image; Keep the convex polygon outline of the incomplete square that needs to be recognized; Find at least two vertices that are not on the edge of the picture; Fill in the vertices of the square based on at least two vertices; Construct a complete square from the vertices of the completed square.

2. The method for identifying an incomplete square in a field of view according to claim 1, characterized in that: The step of finding at least two vertices that are not on the edge of the picture comprises: According to the convex polygonal outline of the incomplete square to be identified, the total number of vertices is obtained to be 4, 5 or 6; if the number of vertices is 4 or 6, two vertices that are not on the edge of the picture are found; if the number of vertices is 5, three vertices that are not on the edge of the picture are found.

3. The method for identifying an incomplete square in a field of view according to claim 2, characterized in that: The step of filling in the vertices of a square according to at least two vertices comprises: If the total number of vertices is 4, construct two squares based on the two vertices that are not at the edge of the picture to form two groups of candidate third vertices and fourth vertices, and retain the candidate third vertices and fourth vertices on the same side of the line connecting the two vertices at the edge of the picture as the third vertex and fourth vertex of the incomplete square; If the total number of vertices is 5, three parallelograms are constructed based on the three vertices that are not on the edge of the screen to form three candidate fourth vertices, and the candidate fourth vertices whose intersecting line lengths satisfy the first predetermined ratio and whose sequential line lengths satisfy the second predetermined ratio are retained as the fourth vertices of the incomplete square; If the number of vertices is 6 in total, a square is constructed based on two vertices that are not on the edge of the picture, forming a third vertex and a fourth vertex.

4. A system for identifying an incomplete square in a field of view, characterized in that: It includes a contour extraction module, a vertex completion module and a square construction module which are connected in sequence; The contour extraction module is used to obtain an image of an incomplete square in the field of view, and adaptively binarize the image; extract all closed contours in the binarized image; retain contours that meet the first picture size ratio relationship; and retain the convex polygonal contour of the incomplete square that needs to be identified; The vertex completion module is used to find at least two vertices that are not on the edge of the picture; and complete the vertices of the square according to the at least two vertices; The square construction module is used to construct a complete square according to the vertices of the padded square.

5. An auxiliary positioning method for aircraft landing, characterized in that: The following steps are involved: S1: Set the nested mark on the ground and obtain the world coordinates of each vertex of each square; The nested mark includes n squares, the nth square is nested in the n-1th square, n is a natural number greater than or equal to 2, and the centers of the nth square and the n-1th square are not in the same position; S2: Continuously photograph the nesting mark from a landing aircraft located above the nesting mark, and the camera focal length remains unchanged during the photographing process; S3: identifying squares in sequence starting from the first square, and if the largest square in the field of view is incomplete, identifying the squares using the method for identifying an incomplete square in the field of view described in any one of claims 1 to 3; S4: Obtain the position of the aircraft according to the image coordinates and world coordinates of each vertex corresponding to the found n-1th square and the nth square, wherein the nth square has at least two vertices in the shooting picture.

6. The auxiliary positioning method for aircraft landing according to claim 5, characterized in that: In step S1, in the nested mark, two nested squares of similar size have different colors, or two nested squares of similar size have the same color and there is an isolation figure of different color and not a square nested with the two squares of similar size.

7. The auxiliary positioning method for aircraft landing according to claim 5, characterized in that: In step S4, obtaining the position of the aircraft according to the image coordinates and world coordinates of each vertex corresponding to the found n-1th square and the nth square includes: Get the direction of the camera based on the positional relationship between the n-1th square and the nth square; According to the direction of the camera, order the four vertices of the n-1th square; According to the order of the four vertices, the pose relationship between the world coordinate system and the image coordinate system of the four vertices is matched through PnP solution to obtain the relative displacement transformation matrix; The position information of the aircraft is obtained according to the relative displacement transformation matrix.

8. The auxiliary positioning method for aircraft landing according to claim 7, characterized in that: The step of obtaining the direction of the camera according to the positional relationship between the n-1th square and the nth square includes: Project the vertices of the two squares to the standard square; The relative positions of the two squares are matched with the template of the nested logo to get the camera's pointing direction.

9. An auxiliary positioning device for aircraft landing, characterized in that: include: Nested markers, a camera, a recognition system for an incomplete square in the field of view as claimed in claim 4, and a position solving module; The nested mark is set on the ground; the nested mark includes n squares, the nth square is nested in the n-1th square, n is a natural number greater than or equal to 2, and the centers of the nth square and the n-1th square are not in the same position; The camera is set on the aircraft, and the nesting mark is continuously photographed from the aircraft that is located above the nesting mark and is landing. The focal length of the camera does not change during the photographing process; The position solution module is used to obtain the world coordinates of each vertex of each square; starting from the first square, the squares are identified in sequence. If the largest square in the field of view is incomplete, the incomplete square recognition system in the field of view is used to identify the square; the position of the aircraft is obtained according to the image coordinates and world coordinates of each vertex corresponding to the found n-1th square and the nth square, wherein the nth square has at least 2 vertices in the shooting picture.

Images