CN113506276A - Marker and method for measuring structure displacement - Google Patents
Marker and method for measuring structure displacement Download PDFInfo
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Abstract
The invention discloses a marker and a method for measuring structural displacement, wherein the marker comprises a bottom plate and a marker pattern arranged on the surface of the bottom plate; the mark pattern comprises a matching template, a code width calibration unit, at least one positioning unit and at least one code area unit; the positioning unit is used for determining the positions of the matching template and the coding region unit; the coding width calibration unit determines the number of pixel points occupied by the coding region unit width according to the number of pixel points occupied by the coding width calibration unit; the matching template is used for matching the marker images before and after the structure displacement; the coding area unit is extracted to carry out pixel scanning, coded data are obtained, and then the unique code ID of the marker is determined, wherein the unique code ID comprises structural displacement information and historical data. The marker provided by the invention has high measurement precision on the structural displacement, and the unique code ID of the marker comprises structural displacement information and historical data, so that the functions of high-efficiency multipoint displacement measurement and historical data analysis can be realized.
Description
Technical Field
The invention relates to the technical field of visual displacement measurement, in particular to a marker and a method for measuring structural displacement.
Background
In the field of visual displacement measurement, artificial markers are often used as feature points. The proper artificial marker can increase the discrimination between target tracking and the surrounding environment; moreover, the artificial marker can be easily and efficiently identified by a computer program, and higher calculation accuracy can be obtained by performing image processing. Template matching is used as a classic technology in the field of visual displacement measurement, and the measurement principle is that a template subregion is selected in an image before structural displacement, then sliding matching is carried out on the image after the structural displacement of the template subregion, and finally, pixel displacement of the template subregion is determined according to the matching correlation degree and converted into actual structural displacement according to the camera calibration geometric relationship. Due to the advantages of fast template matching speed, use of original information, no need of preprocessing and the like, many scholars take the artificial markers as matching templates and conduct extensive research in the measurement of structural displacement. At present, there are still some problems with artificial markers for template matching. When the displacement measurement and the data analysis are carried out on the target structure, the measurement data corresponding to each monitoring point needs to be artificially distinguished, the workload is huge, and the multi-point displacement measurement and the historical data analysis cannot be efficiently realized.
Chinese patent CN209417797U published in 9, 20 and 2019 provides a calibration board based on a mixed mark, wherein the front surface of the calibration board is provided with a plurality of calibration structures, the plurality of calibration structures comprise a plurality of first calibration structures and one or more second calibration structures, and the second calibration structures are two-dimensional code graphic structures; the calibration plate can accurately measure the displacement of a single point, the accuracy can be reduced when the multi-point displacement measurement is carried out, the calibration speed can be reduced, and the multi-point displacement measurement cannot be efficiently realized.
Disclosure of Invention
The invention provides a marker and a method for measuring structural displacement, aiming at overcoming the defect that the prior art cannot realize multi-point displacement measurement and historical data analysis efficiently.
In order to solve the technical problems, the technical scheme of the invention is as follows:
the invention provides a marker for measuring structural displacement, which is characterized in that the marker is fixedly connected with a structure, and the structural displacement is measured by matching the images of the marker before and after the structural displacement; the marker comprises a bottom plate and a marker pattern arranged on the surface of the bottom plate; the mark pattern comprises a matching template, a coding width calibration unit, at least one positioning unit and at least one coding region unit; the matching template, the code width calibration unit, the positioning unit and the coding area unit are separated;
the positioning unit is used for determining the positions of the matching template and the coding region unit;
the coding width calibration unit determines the number of pixel points occupied by the width of the coding region unit according to the number of pixel points occupied by the coding width calibration unit;
the matching template is used for matching the marker images before and after the structure displacement;
the coding region unit is extracted to carry out pixel scanning, coded data are obtained, and then the unique code ID of the marker is determined, wherein the unique code ID comprises structure displacement information and historical data.
Preferably, the number of the positioning units is three; the central points of the three positioning units and the central point of the code width calibration unit are connected in sequence to form a square; the center point of the matching template, the center point of the bottom plate and the center point of the square are superposed.
Preferably, the positioning unit consists of a layer a of concentric rings with alternate black and white and equal ring width; the large diameter of the innermost ring has a proportional relationship x to the small diameter.
Preferably, the matching template consists of b layers of concentric rings with alternate black and white and equal ring width; the large circle diameter of the innermost ring has a proportional relationship y to the small circle diameter.
Preferably, the number of the coding region units is four, and the coding region units are respectively located on four sides of a square formed by the three positioning units and the coding width calibration unit;
the coding region unit consists of a plurality of code elements of two colors, and the code elements of the two colors represent two coding values;
each coding region unit comprises a start bit, a coding bit and an end bit, the start bit and the end bit are the same between the coding region units, the coding bits are different, and the coding data are recorded on the coding bits.
Preferably, the code width calibration unit is a black circle, and the color of the code width calibration unit is different from the color of the bottom plate; the radius of the code width calibration unit has a proportional relationship z with the width of the code bits.
The invention also provides a method for measuring the structural displacement, which utilizes the marker for measuring the structural displacement to measure the structural displacement and comprises the following steps:
s1: obtaining original pictures of the markers before and after the structure displacement;
s2: determining the position of a positioning unit in an original picture of the marker before the structure displacement;
s3: extracting a matching template according to the position of the positioning unit, and performing sliding matching on the original picture of the marker before the structure displacement and the original picture of the marker after the structure displacement by using the matching template;
s4: after matching is completed, the number of pixels occupied by the radius of the code width calibration unit is identified, and the number of pixels occupied by the width of the code area unit is calculated;
s5: extracting all coding region units according to the positions of the positioning units;
s6: and performing pixel scanning on the coding region unit to obtain coded data, and further determining a unique code ID of the marker, wherein the unique code ID comprises structure displacement information and historical data.
Preferably, before determining the position of the positioning unit in the original picture of the marker before structure displacement, the original picture of the marker before structure displacement needs to be preprocessed, including: carrying out graying processing on an original picture of the marker before the structure displacement to obtain a grayscale picture; carrying out binarization processing on the gray level picture to obtain a binarized picture;
before pixel scanning is performed on the coding region unit, preprocessing needs to be performed on the coding region unit, including: carrying out graying processing on the coding region unit to obtain a grayed coding region unit; and carrying out binarization processing on the grayed coding region unit to obtain a binarization coding region unit.
Preferably, in S2, the specific method for determining the position of the positioning unit in the original picture of the marker before the structure displacement is as follows:
s2.1: carrying out contour detection on the binary image to find out all contours;
s2.2: screening the contours with a +1 layer relation from all the contours by using a contour tree method;
s2.3: judging the outlines of all the a +1 layers, screening out the outlines of which the large circle diameters and the small circle diameters of the innermost layer rings have a proportional relation x, and using the outlines as positioning units;
s2.4: carrying out multivariate curve fitting on the outermost layer contour of the positioning unit, and determining the central point pixel coordinate of the positioning unit;
s2.5: and the central point pixel coordinate of the positioning unit is substituted into the vector vertical formula and the inner product formula to determine the position of the positioning unit.
Preferably, in S6, the specific method for obtaining the encoded data by pixel scanning the encoding region unit and then determining the unique encoding ID of the marker includes:
s6.1: one-dimensional pixel scanning is carried out on a binarization coding region unit according to a certain sequence, and obtained pixel values are stored in an array form;
s6.2: traversing the pixel value array, calculating the number of code elements of the coding area unit according to the number of the pixel values and the number of the pixels occupied by the width of the coding area unit obtained in the step S4, converting the pixel values into binary coding values, and storing the binary coding values as the coding value array;
s6.3: and identifying the start bit and the end bit of the coding area unit in the coding value array, extracting the coding bits, and combining all codes into a unique code ID combined as a marker.
Connecting lines between the three positioning units and the code width calibration unit form a square, corresponding sides of the two squares are parallel to each other, and the three positioning units and the code width calibration unit are distributed at 4 vertex angles of the bottom plate; the center point of the matching template, the center point of the bottom plate and the center point of the square are overlapped, so that the matching template is positioned in the square formed by the three positioning units and the code width calibration unit, and the coordinate of the center point of the matching template can be obtained by the coordinate of the center points of the three positioning units, thereby being convenient for the extraction of the matching template; the four coding area units are positioned on four sides of a square formed by the three positioning units and the coding width calibration unit, and after the coding area units are extracted, the scanning can be performed according to a certain sequence, for example, all the coding area units are scanned anticlockwise from the coding width calibration unit, so that errors caused by non-uniform scanning sequence of the coding values of the coding area units are avoided.
The positioning unit consists of a layer a of concentric rings with alternate black and white and equal ring width, and the large circle diameter and the small circle diameter of the innermost ring have a proportional relation x; the matching template consists of b layers of concentric rings with alternate black and white and equal ring width; the large circle diameter and the small circle diameter of the innermost ring have a proportional relation y; wherein a is less than b, x is not equal to y; the proportional relations are unequal, and the positioning units can be accurately screened out; the matching templates are all composed of concentric rings, so that the matching templates have affine invariance, namely, when the marker rotates in the displacement process, the extracted positioning unit and the extracted matching templates cannot change. The reason that the number b of the concentric rings forming the matching template is far larger than the number a of the concentric rings forming the positioning unit is that the matching template has multiple layers of edges, and when small displacement occurs, the ratio of image change components is increased, so that matching before and after the displacement is facilitated.
The radius of the code width calibration unit has a proportional relation z with the width of the code element; calculating the number of pixels occupied by code elements by identifying the number of pixel points occupied by the radius of the code width calibration unit, and further calculating the number of code elements of the coding region unit; the coding region unit consists of a plurality of code elements of two colors, and the code elements of the two colors represent two coding values; each color has a specific pixel value, and after the number of code elements is calculated, a pixel value array of a coding region unit can be obtained; converting the pixel values into code element coding values, wherein the coding values are represented by binary values, the pixel value corresponding to the code element of one color is represented by 1, and the pixel value corresponding to the code element of the other color is represented by 0, and forming a coding value array; according to the set start bit and the set end bit, the coding values of the start bit and the end bit are removed from the coding value array, the coding values of the coding bits are obtained, the coding values of the coding bits of the 4 coding area units form the unique coding ID of the marker, and the functions of high-efficiency identification of multi-point displacement measurement and historical data analysis are achieved.
Compared with the prior art, the technical scheme of the invention has the beneficial effects that:
the marker for measuring the structural displacement has stronger anti-interference capability on imaging distortion, and at least one positioning unit is retrieved and identified, so that the accuracy of extracting a matching template and a coding region unit is ensured while the marker image is rapidly identified; the matching template has affine invariance, the matching template can not change when the marker rotates in the displacement process, the accuracy of the marker image matching process before and after the structural displacement is ensured, and the image change components of the matching template account for more when the structure generates micro displacement, thereby being beneficial to the matching of the marker images before and after the displacement and improving the precision of the displacement measurement; the number of the pixel points occupied by the coding region unit width is determined through the number of the pixel points occupied by the coding width calibration unit, the method is simple, and the calculation speed is high; at least one coding region unit can record richer coded data, and further determine the unique code ID of the marker, wherein the unique code ID comprises structure displacement information and historical data, and the functions of high-efficiency multipoint displacement measurement and historical data analysis are achieved.
Drawings
FIG. 1 is a schematic structural diagram of a marker for measuring structural displacement according to example 1;
FIG. 2 is a diagram of a coding region unit according to embodiment 1;
FIG. 3 is a flowchart of a method of measuring displacement of a structure according to embodiment 2;
fig. 4 is a schematic view of a gray scale picture of a marker before structural displacement according to embodiment 2;
fig. 5 is a schematic diagram of a binarized picture of a marker before structural displacement according to embodiment 2;
FIG. 6 is a schematic view of the position of the positioning unit according to embodiment 2;
FIG. 7 is a diagram of a binarization-encoded region unit in accordance with embodiment 2;
FIG. 8 is a schematic view of scanning a unit of a binarized encoded region according to embodiment 2;
FIG. 9 is a diagram of binary encoding according to embodiment 2;
in the figure, 1-bottom plate, 2-matching template, 3-code width calibration unit, 4-positioning unit and 5-code area unit.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the patent;
for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product;
it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.
Example 1
The embodiment provides a marker for measuring structural displacement, wherein the marker is fixedly connected with a structure, and the structural displacement is measured by matching the images of the marker before and after the structural displacement; as shown in fig. 1, the marker includes a base plate 1 and a marker pattern disposed on a surface of the base plate 1; the mark pattern comprises a matching template 2, a code width calibration unit 3, at least one positioning unit 4 and at least one code area unit 5; the matching template 2, the code width calibration unit 3, the at least one positioning unit 4 and the at least one code area unit 5 are separated;
the positioning unit 4 is used for determining the positions of the matching template 2 and the coding region unit 5;
the coding width calibration unit 3 determines the number of pixel points occupied by the width of the coding region unit 5 according to the number of pixel points occupied by the coding width calibration unit;
the matching template 2 is used for matching the marker images before and after the structure displacement;
the coding area unit 5 is extracted to perform pixel scanning, coded data are obtained, and then the unique code ID of the marker is determined, wherein the unique code ID comprises structure displacement information and historical data.
The number of the positioning units 4 is three; the central points of the three positioning units 4 and the central point of the code width calibration unit 3 are connected in sequence to form a square; the center point of the matching template 2, the center point of the bottom plate 1 and the center point of the square are coincided.
The positioning unit 4 consists of a layer a of concentric rings with alternate black and white and equal ring width; the large diameter of the innermost ring has a proportional relationship x to the small diameter.
The matching template 2 consists of b layers of concentric rings with alternate black and white and equal ring width; the large circle diameter of the innermost ring has a proportional relationship y to the small circle diameter.
The number of the coding region units 5 is four, and the coding region units are respectively positioned on four edges of a square formed by the three positioning units 4 and the coding width calibration unit 3;
the coding region unit 5 is composed of a plurality of symbols of two colors, and the symbols of two colors represent two coding values;
each of the code region units 5 includes a start bit, a coded bit, and an end bit, the start bit and the end bit are the same between the code region units 5, the coded bits are different, and the coded data is recorded on the coded bits.
The code width calibration unit 3 is a black circle, and the color of the code width calibration unit 3 is different from that of the bottom plate 1; the radius of the code width calibration unit 3 has a proportional relationship z with the width of the symbol.
In the specific implementation process, the bottom plate 1 is a white square, and the mark pattern comprises a matching template 2, a code width calibration unit 3, three positioning units 4 and four code area units 5; any two mark patterns are separated; the bottom plate 1 can be made of paper, thin paper boards, plastic boards, steel plates and the like;
the positioning unit 4 comprises 2 layers of concentric rings with black and white alternated and equal ring widths, the inner layer ring is white, the outer layer ring is black, the inner layer ring is filled with black, and the large circle diameter and the small circle diameter of the inner layer ring have a proportional relation of 4: 3; the code width calibration unit 3 is a black circle; connecting lines between the three positioning units 4 and the coding width calibration unit 3 form a square, in order to enable the matching template 2 and the coding region unit 5 to contain more information as much as possible, the three positioning units 4 are respectively positioned at the left lower, left upper and right upper top corners of the bottom plate 1, and the coding width calibration unit 3 is positioned at the right lower top corner of the bottom plate 1; the center point of the matching template 2, the center point of the bottom plate 1 and the center point of the square are overlapped, and the purpose of overlapping the center point of the matching template 2 and the center point of the square is to rapidly extract the matching template 2 according to the coordinates of the positioning unit 4;
the matching template 2 consists of 9 layers of concentric rings with black and white alternated and equal ring widths; the large circle diameter and the small circle diameter of the innermost ring have a proportional relationship 2: 1; when the outline is identified, whether the outline belongs to the positioning unit 4 or the matching template 2 is judged according to the proportional relation between the large circle diameter and the small circle diameter of the innermost circle; the number of layers of the matching template 2 is increased, so that the edges of the matching template 2 are increased, and the ratio of image change components is large when the structure is slightly displaced; concentric rings with black and white phases and equal ring widths are used as the matching template 2, so that the matching template 2 has radiation invariance, and when the marker rotates in the displacement process, the matching template 2 cannot be changed;
the 4 coding region units 5 are respectively positioned on four sides of a square formed by the three positioning units 4 and the coding width calibration unit 3, the coordinates of the positioning units 4 are determined, and the coding region units 5 can be accurately and rapidly extracted; as shown in fig. 2, the coding region unit 5 includes a start bit, a coding bit, and an end bit, the start bit and the end bit being the same, the coding bit being different, a coding value being described on the coding bit; the coding region unit 5 is composed of a plurality of symbols of two colors, and the symbols of the two colors represent two coding values; the number of symbols is determined by a code width calibration unit 3, the radius of the code width calibration unit 3 and the width of the symbols have a proportional relationship 1: 0.7; in this embodiment, each coding region has the same number of code elements, the code elements are filled with black or white, each color has a specific pixel value, the pixel value is represented by a binary coding value, a black code element represents a binary coding value 1, a white code element represents a binary coding value 0, a plurality of code elements can form a start bit, an end bit and a coding bit, the start bit is three code elements, the colors are black, black and black, respectively, and the binary coding value is 111; ending in three code elements, wherein the colors are black, white and black respectively, and the binary code value is 101; extracting the code values of the code bits by identifying the start bit and the end bit, and forming the code values of the code bits of the 4 code area units 5 into a unique code ID of the marker in a certain sequence, such as a clockwise sequence, namely a lower sequence, a left sequence, an upper sequence and a right sequence, starting from the code width calibration unit 3; as shown in FIG. 4, the unique code ID of the marker is 0000010011010010, the code ID comprises monitoring point measurement data and historical data, and the functions of multi-point displacement measurement and historical data analysis are efficiently identified according to the obtained unique code ID.
Example 2
The present embodiment provides a method for measuring structural displacement, which utilizes the marker for measuring structural displacement described in embodiment 1 to measure structural displacement; as shown in fig. 3, includes:
s1: obtaining original pictures of the markers before and after the structure displacement;
s2: determining the position of a positioning unit in an original picture of the marker before the structure displacement;
s3: extracting a matching template according to the position of the positioning unit, and performing sliding matching on the original picture of the marker before the structure displacement and the original picture of the marker after the structure displacement by using the matching template;
s4: after matching is completed, the number of pixels occupied by the radius of the code width calibration unit is identified, and the number of pixels occupied by the width of the code area unit is calculated;
s5: extracting all coding region units according to the positions of the positioning units
S6: and performing pixel scanning on the coding region unit to obtain coded data, and further determining a unique code ID of the marker, wherein the unique code ID comprises structure displacement information and historical data.
Before determining the position of the positioning unit in the original picture of the marker before the structure displacement, the original picture of the marker before the structure displacement needs to be preprocessed, which includes: carrying out graying processing on an original picture of the marker before the structure displacement to obtain a grayscale picture; carrying out binarization processing on the gray level picture to obtain a binarized picture;
before pixel scanning is performed on the coding region unit, preprocessing needs to be performed on the coding region unit, including: carrying out graying processing on the coding region unit to obtain a grayed coding region unit; and carrying out binarization processing on the grayed coding region unit to obtain a binarization coding region unit.
In S2, the specific method for determining the position of the positioning unit in the original picture of the marker before the structure displacement is as follows:
s2.1: carrying out contour detection on the binary image to find out all contours;
s2.2: screening the contours with a +1 layer relation from all the contours by using a contour tree method;
s2.3: judging the outlines of all the a +1 layers, screening out the outlines of which the large circle diameters and the small circle diameters of the innermost layer rings have a proportional relation x, and using the outlines as positioning units;
s2.4: carrying out multivariate curve fitting on the outermost layer contour of the positioning unit, and determining the central point pixel coordinate of the positioning unit;
s2.5: and the central point pixel coordinate of the positioning unit is substituted into the vector vertical formula and the inner product formula to determine the position of the positioning unit.
In S6, the specific method of performing pixel scanning on the coding region unit to obtain coded data and further determining the unique code ID of the marker includes:
s6.1: one-dimensional pixel scanning is carried out on a binarization coding region unit according to a certain sequence, and obtained pixel values are stored in an array form;
s6.2: traversing the pixel value array, calculating the number of code elements of the coding area unit according to the number of the pixel values and the number of the pixels occupied by the width of the coding area unit obtained in the step S4, converting the pixel values into binary coding values, and storing the binary coding values as the coding value array;
s6.3: and identifying the start bit and the end bit of the coding area unit in the coding value array, extracting the coding bits, and combining all codes into a unique code ID combined as a marker.
In the specific implementation process, S1: acquiring original pictures of the markers before and after the structure displacement from the photographing equipment, and carrying out graying processing on the original pictures of the markers before the structure displacement to obtain a grayscale picture, wherein the grayscale picture is shown in fig. 4; performing binarization processing on the gray level picture to obtain a binarized picture as shown in fig. 5;
s2: determining the position of the positioning unit in the binarized picture, as shown in fig. 6, specifically:
s2.1: carrying out contour detection on the binary image to obtain all contours;
s2.2: screening the contours with 3-layer relation in all contours by using a contour number method; the positioning unit consists of 2 layers of concentric rings, and the 2 layers of concentric rings have a 3-layer relation outline;
s2.3: judging all the profiles of the 3 layers, and screening out the large circle diameter and the small circle diameter of the innermost ring with a proportional relation of 4: 3 as a positioning unit;
s2.4: carrying out multivariate curve fitting on the outermost layer contour of the positioning unit, and determining the central point pixel coordinate of the positioning unit;
s2.5: substituting the pixel coordinates of the central point of the positioning unit into a vector vertical formula and an inner product formula to determine the position of the positioning unit;
the coordinates of the center point pixels of the three positioning units are (x1, y1), (x2, y2), (x3, y3), for example, because the connecting lines between the three positioning units and the code width calibration unit form a square, the abscissa of the center point pixel coordinates of the two positioning units is equal, and the ordinate of the center point pixel coordinates of the two positioning units is equal, through the vector vertical formula, if (x2-x1, y2-y1) · (x2-x3, y2-y3) ═ 0, then the positioning unit corresponding to (x2, y2) is located at the top left corner, and then through the inner product formula, if (x1-x2, y1-y2,0) (x3-x2, y3-y2,0) (a, b, c), and c >0, then the top left corner corresponding to (x1, y1) is located at the top left corner, and the top corner corresponding to x3, y 632 is located at the top right corner corresponding to (x 3), otherwise, the opposite is true;
s3: extracting a matching template according to the position of the positioning unit, and performing sliding matching on the original picture of the marker before the structure displacement and the original picture of the marker after the structure displacement by using the matching template;
determining the pixel coordinates of the central points of the three positioning units, taking the positioning unit at the lower left vertex as (x1, y1), the positioning unit at the upper left vertex as (x2, y2) and the positioning unit at the upper right vertex as (x3, y3) as an example, and if the center of the matching template coincides with the center of a square formed by connecting lines between the three positioning units and the code width calibration unit, the pixel coordinates of the center of the matching template are (x4, y4), x4 is (x3-x1)/2, and y4 is (y3-y 1)/2; extracting a matching template according to the pixel coordinates of the center of the matching template, and performing sliding matching on the matching template and the picture after the flag bit is displaced;
s4: after matching is completed, the number of pixels occupied by the radius of the code width calibration unit is identified, and the number of pixels occupied by the width of the code area unit is calculated;
carrying out Hough transform on a right lower vertex angle area of the marker, and coding the number of pixels occupied by the radius of the width calibration unit and recording as R; since the radius of the code width calibration unit has a proportional relationship 1 with the width of the symbol: 0.7, if the number of pixels occupied by the width of a single code element is denoted as R, then R is 0.7 × R;
s5: extracting all coding region units according to the positions of the positioning units; carrying out graying processing on the coding region unit to obtain a grayed coding region unit; performing binarization processing on the grayed coding region unit to obtain a binarization coding region unit, as shown in fig. 7;
s6: pixel scanning is carried out on the coding region unit to obtain coded data, and then the unique code ID of the marker is determined, wherein the unique code ID comprises structure displacement information and historical data; specifically, the method comprises the following steps:
s6.1: as shown in fig. 8, the coding region unit is subjected to one-dimensional pixel scanning in the order of down, left, up, and right, and the obtained pixel values are stored in an array form;
s6.2: traversing the pixel value array, calculating the number of code elements of the coding area unit according to the number of the pixel values and the number of the pixels occupied by the width of the coding area unit obtained in the step S4, converting the pixel values into binary coding values, and storing the binary coding values as the coding value array;
in this embodiment, the encoding area unit is composed of a plurality of code elements of two colors, black and white, each color has a specific pixel value, the black pixel value is 255, and the white pixel value is 0;
dividing the number of pixel values by the number r of pixels occupied by the width of a single code element to obtain the number of code elements of a coding region unit; as shown in fig. 9, the pixel value is converted into a binary coded value, the binary coded value of the pixel value 255 is 1, and the binary coded value of the pixel value 0 is 0; storing all binary coded values as a coded value array;
s6.3: and identifying the start bit and the end bit of the coding area unit in the coding value array, extracting the coding bits, and combining all codes into a unique code ID combined as a marker.
In this embodiment, the start bit is three code elements, the colors are black, and black, respectively, and the binary code value is 111; ending in three code elements, wherein the colors are black, white and black respectively, and the binary code value is 101; and extracting the coded values of the coded bits by identifying the start bit and the end bit, and forming the coded values of the coded bits of the 4 coded area units into a unique code ID of the marker according to a certain sequence.
The same or similar reference numerals correspond to the same or similar parts;
the terms describing positional relationships in the drawings are for illustrative purposes only and are not to be construed as limiting the patent;
it should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (10)
1. A marker for measuring structural displacement is characterized in that structural displacement is measured by matching marker images before and after structural displacement; the marker is characterized by comprising a bottom plate (1) and a marker pattern arranged on the surface of the bottom plate (1); the mark pattern comprises a matching template (2), a code width calibration unit (3), at least one positioning unit (4) and at least one coding region unit (5); the matching template (2), the coding width calibration unit (3), the positioning unit (4) and the coding region unit (5) are separated;
the positioning unit (4) is used for determining the positions of the matching template (2) and the coding region unit (5);
the coding width calibration unit (3) determines the number of pixel points occupied by the width of the coding region unit (5) according to the number of pixel points occupied by the coding width calibration unit;
the matching template (2) is used for matching the marker images before and after the structure displacement;
the coding region unit (5) is extracted according to the position of the coding region unit (5) determined by the positioning unit (4), the coding region unit (5) is subjected to pixel scanning to obtain coding data, and further the unique code ID of the marker is determined, wherein the unique code ID comprises structure displacement information and historical data.
2. Marker for measuring the displacement of a structure according to claim 1, characterized in that the number of said positioning units (4) is three; the central points of the three positioning units (4) and the central point of the code width calibration unit (3) are connected in sequence to form a square; the center point of the matching template (2), the center point of the bottom plate and the center point of the square are coincided.
3. The marker for measuring structural displacements according to claim 2, characterized in that said positioning unit (4) consists of a layer of concentric rings with alternate black and white, equal ring widths; the large diameter of the innermost ring has a proportional relationship x to the small diameter.
4. Marker for measuring structural displacements according to claim 2, characterized in that said matching template (2) consists of b layers of concentric rings with black and white phases, equal ring widths; the large circle diameter of the innermost ring has a proportional relationship y to the small circle diameter.
5. Marker for measuring structural displacements according to claim 3, characterized in that said coding area cells (5) are four in number, respectively on the four sides of the square constituted by the three positioning cells (4) and the coding width calibration cells (3);
the coding region unit (5) is composed of a plurality of symbols of two colors, and the symbols of the two colors represent two coding values;
each coding region unit (5) comprises a start bit, a coding bit and an end bit; the start bit and the end bit are the same between the encoding area units (5), the encoding bits are different, and the encoded data is recorded on the encoding bits.
6. The marker for measuring structural displacement according to claim 5, wherein the code width calibration unit (3) is a black circle, and the color of the code width calibration unit (3) is different from the color of the base plate; the radius of the code width calibration unit (3) has a proportional relationship z with the width of the code bits.
7. A method for measuring structural displacement by using the marker for measuring structural displacement according to claim 1, comprising:
s1: obtaining original pictures of the markers before and after the structure displacement;
s2: determining the position of a positioning unit in an original picture of the marker before the structure displacement;
s3: extracting a matching template according to the position of the positioning unit, and performing sliding matching on the original picture of the marker before the structure displacement and the original picture of the marker after the structure displacement by using the matching template;
s4: after matching is completed, the number of pixels occupied by the radius of the code width calibration unit is identified, and the number of pixels occupied by the width of the code area unit is calculated;
s5: extracting all coding region units according to the positions of the positioning units;
s6: and performing pixel scanning on the coding region unit to obtain coded data, and further determining a unique code ID of the marker, wherein the unique code ID comprises structure displacement information and historical data.
8. The method of claim 7, wherein before determining the position of the positioning unit in the original image of the marker before structure displacement, the original image of the marker before structure displacement needs to be preprocessed, and the preprocessing includes: carrying out graying processing on an original picture of the marker before the structure displacement to obtain a grayscale picture; carrying out binarization processing on the gray level picture to obtain a binarized picture;
before pixel scanning is performed on the coding region unit, preprocessing needs to be performed on the coding region unit, including: carrying out graying processing on the coding region unit to obtain a grayed coding region unit; and carrying out binarization processing on the grayed coding region unit to obtain a binarization coding region unit.
9. The method for measuring structural displacement according to claim 8, wherein in step S2, the specific method for determining the position of the positioning unit in the original picture of the marker before structural displacement is as follows:
s2.1: carrying out contour detection on the binary image to find out all contours;
s2.2: screening the contours with a +1 layer relation from all the contours by using a contour tree method;
s2.3: judging the outlines of all the a +1 layers, screening out the outlines of which the large circle diameters and the small circle diameters of the innermost layer rings have a proportional relation x, and using the outlines as positioning units;
s2.4: carrying out multivariate curve fitting on the outermost layer contour of the positioning unit, and determining the central point pixel coordinate of the positioning unit;
s2.5: and the central point pixel coordinate of the positioning unit is substituted into the vector vertical formula and the inner product formula to determine the position of the positioning unit.
10. The method for measuring structural displacement according to claim 9, wherein in S6, the specific method for obtaining the encoded data by pixel scanning the encoded region unit and then determining the unique code ID of the marker is as follows:
s6.1: one-dimensional pixel scanning is carried out on a binarization coding region unit according to a certain sequence, and obtained pixel values are stored in an array form;
s6.2: traversing the pixel value array, calculating the number of code elements of the coding area unit according to the number of the pixel values and the number of the pixels occupied by the width of the coding area unit obtained in the step S4, converting the pixel values into binary coding values, and storing the binary coding values as the coding value array;
s6.3: and identifying the start bit and the end bit of the coding area unit in the coding value array, extracting the coding bits, and combining all codes into a unique code ID combined as a marker.
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