How to measure eggs

Abstract

An egg (10) of unknown size being conveyed by a conveyor is photographed from directly above with a camera (25). In obtaining the real size from the size of the image of the egg, a reference plane (20) of which the distance from the camera is a predetermined value H is set. A plurality of eggs of different sizes and a known maximum minor-axis radius (r) are placed on the reference plane and photographed in advance, whereby the relationship between the real length of the maximum minor-axis radius and the length in imaging is obtained, and the relationship between the ratio of the length in imaging to the real length and the height h from the reference plane is obtained. Should the conveyor is a bar conveyor, the bar conveyor would compensate for the depth Δh at which the lower part of an egg gets stuck between bars (40).

Description

[Technical Field]

[0001] The present invention relates to an egg measuring method for measuring the size of eggs. [Background technology]

[0002] The mass of eggs produced in a facility where birds are raised can be used to determine whether the bird's rearing environment and feeding conditions are appropriate, and whether the birds are in good health, and can therefore be used as useful information for managing the birds being raised.

[0003] Meanwhile, at the Grading and Packing Center (hereinafter referred to as "GP Center"), the weight of all eggs shipped from poultry farms is measured, and they are classified according to weight as follows, and then packed and boxed according to each classification. LL: 70g or more, less than 76g L: 64g or more, less than 70g M: 58g or more, less than 64g MS: 52g or more, less than 58g S: 46g or more, less than 52g SS: 40g or more, less than 46g

[0004] In large poultry farms, it is common to raise birds of the same age (birds born on the same day) in one chicken house. Although there is some individual variation, most birds of the same age lay eggs of about the same mass. Therefore, when egg mass measurements are carried out for each chicken house at the GP Center, most eggs have a similar mass, so eggs are concentrated in only the lanes for packaging eggs of a certain size, leaving empty lanes for packaging eggs of other sizes, resulting in inefficient processing.

[0005] In order to efficiently process eggs at GP centers, it is desirable to process eggs that are collected with an even mix of various sizes. Therefore, eggs produced in multiple chicken houses are usually mixed together when processed at GP centers. In this case, the weight of eggs measured at GP centers does not provide useful information for managing chickens at poultry farms.

[0006] Furthermore, even if it is possible to link the eggs whose mass has been measured at the GP center to the poultry farm from which they were shipped, it takes a certain number of days from the time the eggs are laid until the mass measurement results are fed back to the poultry farm.Poultry farms want to know the short-term causal relationship between egg mass and the rearing and management conditions of the birds, such as whether the feeding conditions of the previous day affected the mass of the eggs produced that day.

[0007] For these reasons, it is desirable for poultry farms to independently measure the weight of eggs produced at their own facilities, separate from measurements at GP centers. Large poultry farms produce a huge number of eggs every day, so it is desirable for measurements to be carried out automatically, without the need for human labor.

[0008] The applicant came up with the idea that it might be possible to measure the size of eggs while they are being transported on a conveyor using automated measurement. If the size could be measured accurately, it would be possible to estimate the mass as well. Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the above circumstances, an object of the present invention is to provide an egg measuring method that can accurately measure the size of eggs being transported by a conveyor. [Means for solving the problem]

[0010] In order to solve the above problems, the egg measuring method according to the present invention comprises: "This method involves photographing eggs of unknown size being transported on a conveyor with a camera from directly above, measuring the size of the image of the egg extracted from the image, and determining the actual size of the egg. When the three-dimensional shape of an egg is considered to be a body of revolution, the central axis of rotation is defined as the major axis, and the radius of the countless cross-sectional circles perpendicular to the major axis is defined as the longest radius. A reference plane is set at a predetermined distance from the camera, A first relational expression is obtained in advance by placing a plurality of eggs of different sizes and having known maximum minor axis radii, or a sphere having a known radius, on a reference plane and photographing the eggs, and the first relational expression is obtained from the first relational expression to determine a second relational expression that indicates a change in the ratio of the length in the image to the real length depending on the height from the reference plane; The size of the egg image is converted into real size based on the first and second relations.

[0011] Extraction of the egg image from the image and measurement of the egg size on the image can be performed by image analysis.

[0012] If the size of the egg varies, the distance from the camera photographing the egg from directly above will change. For example, a larger egg will appear larger in the image. In other words, although the goal is to determine the egg's real size from the image of the egg in the image, if the egg's real size varies, the relationship between the size of the image of the egg and its real size will change, which is a problem.

[0013] Therefore, in the present invention, the relationship is determined in advance by placing multiple eggs of different sizes with known maximum minor axis radii, or a sphere with a known radius, on a reference plane and photographing them. The reason for focusing on the maximum minor axis radius is that when an egg placed on the reference plane is photographed from directly above, the outline of the egg at a height from the reference plane equal to the maximum minor axis radius is the outline of the egg in the image. This relationship is unique to the case where the subject of photography is an egg that, when placed somewhere, is stable with its major axis oriented horizontally. A sphere with a known radius can be used instead of an egg of known size because, when the three-dimensional shape of an egg is considered to be a rotating object with the central axis of rotation as the major axis, the cross section perpendicular to the major axis is circular. The radius of the sphere can be considered to be the maximum minor axis radius of an egg of known size.

[0014] The relational expressions are determined by first determining a first relational expression that expresses the relationship between the real length of the maximum minor axis radius and the maximum minor axis radius in the image, and then from the first relational expression, by further determining a second relational expression that expresses the change in the ratio of the length in the image to the real length depending on the height from the reference plane. In determining these relational expressions, only the maximum minor axis radius needs to be measured for both the actual egg and the image of the egg, making the process of determining the relational expressions simple.

[0015] According to the present invention, by using the first and second relational expressions, as will be described in detail below, the problem of the distance from the camera changing depending on the size of the egg can be solved, and the size of the photographed image of the egg can be converted into the real length of the egg.

[0016] In addition to the above configuration, the egg measurement method according to the present invention further comprises: "A conveyor is a conveyor whose conveying surface is a reference surface. If the contour in the image of the egg is the contour of the egg placed on a reference plane at a height h from the reference plane, Using the relationship where height h is the real length of the maximum minor axis radius, The real length of the maximum minor axis radius obtained from the first relational expression can be used as the height from the reference plane in the second relational expression to convert the size on imaging into the real length.

[0017] In this configuration, eggs of unknown size being transported on the conveyor can be considered to be eggs placed on a reference plane. Therefore, by using the second relational expression as the height from the reference plane, the real length of the maximum minor axis radius calculated from the maximum minor axis radius on the image using the first relational expression, it is possible to convert lengths other than the maximum minor axis radius in the image into real lengths.

[0018] The egg measuring method according to the present invention includes, instead of the above configuration, "The conveyor is a bar conveyor that holds and transports eggs between the bars. When the outline of the egg image is the outline of the egg held between the bars at a height h from the reference plane, the interval between the bars is 2d, the real length of the maximum minor axis radius is r, and the reference plane is aligned with the imaginary plane connecting the top lines of the bars, h=(r 2 -d 2 ) 1 / 2 Using the above relationship, we can derive the third relational expression that shows the relationship between the size of the image of the egg and the actual size of the egg from the second relational expression. The real size of an egg whose major axis is aligned with the axial direction of the bar can be determined from the third relational expression.

[0019] This configuration is a method for counting eggs when the conveyor that transports the eggs is a bar conveyor. When eggs are transported by a bar conveyor, the eggs are positioned so that their bottoms are wedged between the bars. The depth to which the eggs are wedged between the bars varies depending on the size of the egg and the angle between the long axis of the egg and the axial direction of the bars, so the second relational expression above cannot be used as is, which creates a problem.

[0020] In this configuration, when the long axis of the egg is aligned with the axial direction of the bar, h = (r 2 -d 2 ) 1 / 2 (2d: bar spacing, r: real length of maximum minor axis radius) can be considered to hold. 2 -d 2 ) 1 / 2By doing so, the size in the image can be converted into the real size.

[0021] Note that eggs transported on a bar conveyor typically have various orientations. By rotating the bars around their respective axes in at least a portion of the transport path of the bar conveyor, the orientation of the eggs can be aligned so that their long axes are aligned with the axial direction of the bars. This is because, as the eggs rotate with the rotation of the bars, they change into a stable position by fitting deepest between the bars. Therefore, by rotating the bars around their axes in at least a portion of the transport path of the bar conveyor upstream of the location where the camera takes photographs, the eggs can be aligned before being photographed, and the present invention can be applied to almost all of the eggs transported.

[0022] Next, the egg measuring method according to the present invention includes the steps of: "This method involves photographing eggs of unknown size being transported on a conveyor with a camera from directly above, measuring the size of the image of the egg extracted from the image, and determining the actual size of the egg. The conveyor is a bar conveyor that holds and transports eggs between the bars. When the three-dimensional shape of the egg is considered to be a rotating body, the axis of rotation is the long axis. A table is created in advance that associates the imaged size with the real size and angle by holding a plurality of eggs or egg-shaped substitutes of different sizes, each having a known size, between the bars at different angles that the long axis of the egg or egg-shaped substitute forms with the axial direction of the bars, and photographing the eggs or egg-shaped substitutes. The real size of the egg can be determined from the table by measuring the size of the image of the egg and the angle between the long axis of the image and the axis of the bar.

[0023] This configuration is a method for counting eggs when the conveyor that transports the eggs is a bar conveyor and the eggs have various orientations. As mentioned above, the depth to which the egg becomes trapped between the bars varies depending on the orientation of the egg as well as the size of the egg. As the angle between the long axis of the egg and the axial direction of the bars approaches a right angle, the depth of the trapped egg decreases, and the degree of this decrease is greater for larger eggs. On the other hand, as the angle between the long axis of the egg and the axial direction of the bars decreases, the depth of the trapped egg increases, and the degree of this decrease is greater for smaller eggs.

[0024] Therefore, in this method, a plurality of eggs of different sizes but known in advance are held between bars in various orientations, and a table is created that associates the imaged size with the real size and angle. The size of interest in creating the table may be the maximum minor axis radius or the major axis diameter (described later), or a table may be created for both. The table also reveals the ratio between the imaged size and the real size. Therefore, if the real length of the size of interest in creating the table is known, this ratio can be used to convert other imaged sizes to real sizes. Note that instead of a plurality of eggs of different sizes but known in size, a substitute such as an egg-shaped model may be used. [Effects of the Invention]

[0025] As described above, the present invention provides an egg measuring method that can accurately measure the size of eggs being transported by a conveyor. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1(a) is an explanatory diagram of photographing an egg placed on a reference plane, and FIG. 1(b) is a diagram showing the image capture. [Figure 2] FIG. 2 is a schematic explanatory diagram of a method for determining the volume of an egg. [Figure 3] Figure 3 is an explanatory diagram showing how the distance from the camera changes depending on the size of the egg. [Figure 4]FIG. 4(a) is a graph illustrating the first relational expression, and FIG. 4(b) is a graph illustrating the second relational expression. [Figure 5] FIG. 5 is an explanatory diagram of a method for determining the first relational expression. [Figure 6] 6(a) and 6(b) are diagrams showing eggs being transported on a bar conveyor. [Figure 7] 7(a) to 7(c) are diagrams illustrating that the depth to which an egg fits between the bars varies depending on the size of the egg. [Figure 8] 8(a) and 8(b) are explanatory diagrams of a method for determining the height h from the reference plane of an egg held between bars. [Figure 9] FIG. 9(a) is a graph showing the relationship between the maximum minor axis radius (real length) of an egg held between the bars and the height h from the reference plane, and FIG. 9(b) is a graph illustrating the third relational expression. [Figure 10] Figure 10 is a graph showing how the angle between the long axis of the egg and the axis of the bar affects size measurements. [Figure 11] FIG. 11(a) is the first table, and FIG. 11(b) is the second table. [Figure 12] FIG. 12 is an explanatory diagram showing how the three-dimensional shape of an egg can be considered as a solid of revolution. DETAILED DESCRIPTION OF THE INVENTION

[0027] Specific embodiments of the present invention will be described below with reference to the drawings. In this embodiment, an egg measurement method involves photographing eggs 10 being transported by a conveyor from above with a camera 25, and determining the real size of the eggs 10 based on the image 30.

[0028] First, as shown in Figure 1(a), consider the case where an egg 10 placed on a reference plane 20 at a distance H from the camera 25 is photographed from directly above using a camera 25 with its optical axis Z in the vertical direction, and an image 30 (still image) including an image 10d of the egg is obtained, as shown in Figure 1(b). The three-dimensional shape of the egg 10 is considered to be a body of revolution as shown in Figure 12, and the central axis of rotation is called the "major axis L". Of the lines connecting two points on the outline of a cross section of the egg 10 cut by a plane including the major axis L, the length of the line connecting the two points P1 and P2 with the longest length is called the "major axis diameter LD". The radii of the countless cross-sectional circles perpendicular to the major axis L are collectively called the "minor axis radius SRn", and the longest of the minor axis radii SRn is called the "maximum minor axis radius SR". max "

[0029] The outline of the image 10d of the egg photographed from directly above by the camera 25 can be considered to be the outline at the height where the outline of the egg 10 is largest when cut on a horizontal plane, and this is called the "maximum outline." For an actual egg 10, if the height from the reference plane 20 to the maximum outline is h, the height h is the maximum minor axis radius SR max This is a relationship specific to the case where the egg 10 to be photographed is most stable when its long axis L is horizontal. h=SR max

[0030] The major axis diameter, minor axis radius, and maximum minor axis radius of the egg image 10d extracted from the imaging 30 will be referred to as follows, respectively, to distinguish them from those of the actual egg 10. Long axis diameter LD ’ Minor axis radius SR ’ n Maximum minor axis radius SR ’ max

[0031] The major axis diameter LD for the egg image 10d ’ , minor axis radius SR ’ n, and maximum minor axis radius SR ’ max The actual lengths of the major axis diameter LD, minor axis radius SRn, and maximum minor axis radius SR maxIf the volume of egg 10 can be converted into the above equation, the volume of egg 10 can be calculated. For example, as shown in FIG. 2, egg 10 can be divided at regular intervals ΔL in the direction of major axis L, and the three-dimensional shape of egg 10 can be approximated as a stack of disks with thickness ΔL and radius SRn (shown as dashed dotted line), thereby calculating the volume of egg 10. Alternatively, the volume of egg 10 can be calculated by finding a formula representing the minor axis radius SRn and integrating the area of ​​a circle with radius SRn in the direction of major axis L over the major axis diameter LD.

[0032] Since the density of the egg 10 is almost constant and is not significantly affected by differences in the size of the egg 10, the density of a sufficient number of eggs is measured in advance and the average value is calculated. The mass of the egg 10 can be estimated by multiplying the volume of the egg 10 by the density.

[0033] In other words, if the size of the egg image 10d can be converted into the actual size of the egg 10, the volume and mass of the egg 10 can be calculated.

[0034] However, as shown schematically in Figure 3, if the size of the egg 10 differs, the height h from the reference plane 20 to the maximum contour will differ, which poses a problem. In other words, the distance Hc from the camera 25 to the maximum contour will vary depending on the size of the egg 10. For example, a larger egg will appear larger in the image. Therefore, the relationship between the length in the egg image 10d and the real length of the egg 10 will differ depending on the size of the egg 10.

[0035] Therefore, it is necessary to investigate in advance how the relationship between the length in the egg image 10d and the real length changes with respect to the height h from the reference plane. max A plurality of eggs 10, each of which has a known radius, are placed on the reference plane 20 and photographed under the same photographing conditions. The reason for focusing on the maximum minor axis radius is that, as described above, the height h from the reference plane 20 to the maximum contour is the maximum minor axis radius SR max This is because eggs have a characteristic relationship in which they are equal to each other.

[0036] This results in a linear relational equation as shown in Figure 4(a). This is called the first relational equation. If this linear equation is y=ax+b, then "x" is the maximum minor axis radius SR, which is the real length. max " and "height h". From the first relational expression, "coefficient k = x / y" is found. Coefficient k is the ratio between the length on the image 30 and the real length. As shown in Figure 4(b), the relationship between coefficient k and height h is also a linear expression. This is called the second relational expression.

[0037] If an egg 10 of unknown size is photographed under the same photographing conditions as when the above relational expression was obtained, the real size of the egg 10 can be determined from the size in the egg image 10d by using the above relational expression. For example, the maximum minor axis radius SR in the egg image 10d can be calculated by ’ max When the length is a certain length, the maximum minor axis radius SR, which is the real length, is obtained from the first relation in Figure 4(a). max The coefficient k at the height h can be found from the second relational expression in Figure 4(b). Therefore, the major axis diameter LD of the egg image 10d is ’ and minor axis radius SR ’ By multiplying each by a coefficient k, it can be converted into the real length, that is, the major axis diameter LD and the minor axis radius SRn.

[0038] In the above, in order to obtain the relational expressions shown in Figures 4(a) and 4(b), the maximum minor axis radius SR max In this example, a plurality of eggs with known sizes are placed on the reference plane 20 and photographed. Alternatively, as shown in FIG. 5, spheres 51 with various known radii R can be used. If such spheres 51 are placed on the reference plane 20 and photographed under the same photographing conditions, the same relational expression as the first relational expression above can be found from the radii of the spheres in the photograph 30. The reason that spheres 51 with known radii can be used instead of eggs with known sizes is that the focus in finding the relational expression is the maximum minor axis radius SR max The radius R of the sphere is the maximum minor axis radius SR of the egg whose size is known. max It can be likened to.

[0039] <When the conveying surface of the conveyor is flat (first embodiment)> Consider a case where the conveyance surface is flat, such as when the conveyor along which eggs 10 are transported is a belt conveyor. When eggs 10 being transported on the conveyor are photographed from directly above, reference plane 20 coincides with the conveyance surface. Therefore, by using the above procedure, the size of egg image 10d can be converted to the actual size of egg 10, and further the volume of egg 10 can be calculated, allowing the mass to be estimated.

[0040] <When the conveyor is a bar conveyor (second embodiment)> Because eggs 10 have a shape that makes them prone to rolling, bar conveyors are often used to transport them. A bar conveyor is a conveyor consisting of a number of bars 40, each supported at both ends by a pair of endless chains, lined up at regular intervals. Since the eggs 10 are transported with their bottoms fitted between the bars 40, they are transported in a stable position without rolling.

[0041] When the lower part of egg 10 gets stuck between bars 40, the distance Hc from camera 25 to the maximum contour becomes larger by the depth of the jamming compared to when the egg is placed on reference surface 20. Furthermore, the depth to which the lower part of egg 10 gets stuck between bars 40 varies depending on the orientation of the egg with respect to bars 40, as shown in Figures 6(a) and 6(b), and also varies depending on the size of egg 10, as shown in Figures 7(a) to 7(c). Therefore, when attempting to determine the real size of egg 10 from image 30 taken from directly above egg 10 being transported by a bar conveyor, the first and second relational expressions described above using Figures 4(a) and 4(b) cannot be used as is.

[0042] When the long axis L of the egg 10 coincides with the axial direction of the bars 40, as shown in Figures 8(a) and 8(b), when the egg 10 held between the bars 40 is viewed from the axial direction of the bars 40, the maximum minor axis radius SR maxis a circle with radius r. Figure 8(b) shows a case where a larger egg 10 than that shown in Figure 8(a) is held between bars 40. As is clear from these figures, the depth Δh to which the egg 10 gets stuck between bars 40 increases as the egg 10 gets smaller. If we take the reference plane 20, which is at a distance H from the camera 25, to be an imaginary plane connecting the top lines of the bars 40, and the distance between the bars 40 to be 2d, then, using Pythagoras' theorem, we can approximate that the following relationship holds between the height h from the reference plane 20 to the maximum contour and the radius r. r 2 =h 2 +d 2 Therefore, h=(r 2 -d 2 ) 1 / 2

[0043] In this equation, radius r (maximum minor axis radius SR max If various values ​​are substituted for h=(r 2 -d 2 ) 1 / 2 Substituting the value of (a) for the height h into the second relational expression in FIG. 4(b), we obtain a linear expression that shows the relationship between the length of the egg 10 held between the bars 40 on the image 30 and its real length, as shown in FIG. 9(b). This is called the third relational expression. Therefore, the major axis diameter LD ’ , minor axis radius SR ’ n, and maximum minor axis radius SR ’ max By measuring the above, the real length of the major axis diameter LD, the minor axis radius SRn, and the maximum minor axis radius SR can be calculated by the third relational expression. max This can be converted to calculate the volume of 10 eggs and estimate their mass.

[0044] When eggs are transported on a bar conveyor, they are generally oriented in various directions. A typical bar conveyor transports items without the bars rotating around their axes. In contrast, in this embodiment, the bars are rotated around their axes in at least a portion of the transport path of the bar conveyor, thereby aligning the eggs so that their long axes L align with the axial direction of the bars. Eggs held between the rotating bars rotate as the bars rotate. During this rotation, eggs that were transported in a position where their long axes L do not align with the axial direction of the bars change to a position where their long axes L align with the axial direction of the bars. This position allows the eggs to fit deeper between adjacent bars, making them more stable.

[0045] Therefore, by rotating the bar around its axis in at least a portion of the bar conveyor's transport path upstream of the camera's location and aligning the eggs so that their long axis L coincides with the axial direction of the bar, the real size of the eggs can be determined using the third relational expression described above with reference to Figures 9(a) and 9(b). One method for rotating the bar around its axis is to, for example, make the bar rotatable and place a plate that comes into contact with the bar below the bar conveyor's transport path. As the bar moves, it rotates due to contact with the plate.

[0046] <When the conveyor is a bar conveyor (third embodiment)> This section explains how to determine the real size of eggs by photographing them from directly above with a camera when eggs of various orientations are transported on a bar conveyor without being aligned. As described above, eggs transported on a bar conveyor become stuck between the bars, and the depth to which they get stuck varies depending on the size of the egg. In addition, if the angle between the long axis of the egg and the axial direction of the bars is different, the depth to which the egg gets stuck between the bars is affected, as shown in Figure 11, which affects the length in the image. Figure 11 is a graph showing the values ​​(calculated values) converted from the long axis diameter in the image, along with the real length of the long axis diameter, for eggs A and B of different sizes, which were photographed while held between the bars with their long axes at different angles to the axial direction of the bars. The calculated values ​​were calculated using the second relational expression when the eggs were placed on a reference surface, without considering the depth to which they get stuck between the bars.

[0047] As can be seen from Figure 11, if the depth of the egg trapped between the bars is not taken into consideration, the length calculated from the size in the image will be smaller than the actual size. This is because the distance from the camera increases by the depth of the trapped egg. The extent to which the calculated value is smaller than the actual length increases not only as the egg size decreases, but also as the angle between the long axis of the egg and the axial direction of the bars decreases.

[0048] Therefore, multiple eggs of various sizes whose sizes are known in advance are held between bars so that the angle θ of the major axis L relative to the axial direction of the bars varies between 0° and 90°, and are photographed from directly above under the same photographing conditions. The lengths in the photographed images are measured, and a table is created that corresponds the lengths in the photographed images to the real lengths for each angle θ, as shown in Figure 11(a). This is referred to as the first table. Here, the major axis diameter of the egg size is known, and a table that corresponds to the major axis diameter in the image is shown as an example, but the size of interest is not limited to the major axis diameter, and the maximum minor axis radius or maximum minor axis diameter (the diameter of the largest cross-sectional circle perpendicular to the major axis) may also be used.

[0049] Furthermore, based on the first table, a table is created in which the ratio between the real length and the imaged length corresponds to the real length for each angle θ, as shown in Fig. 11(b). This is referred to as the second table. Fig. 11(b) illustrates a case in which the ratio is the imaged length relative to the real length.

[0050] Then, an egg of unknown size being transported on a bar conveyor with the same conditions as when these tables were created, such as bar spacing, is photographed from directly above under the same photographing conditions. From the obtained image, an image of the egg is extracted by image analysis, and an image of the bar is also extracted. If the shapes of eggs of different sizes are considered to be similar, the size in the image of the egg can be measured, and the angle θ of the major axis L relative to the axial direction of the bar can be measured in the photograph, and the real size of the egg can be determined by using the first and second tables. For example, in the photograph, the major axis diameter LD ’When the angle θ is 30° and the actual major axis diameter LD is 57.4 mm, the first table shows that the actual major axis diameter LD of the egg is 58.0 mm. When the actual major axis diameter LD is 58.0 mm and the angle θ is 30°, the second table shows that the ratio of the imaged length to the real length is 0.99. Therefore, the minor axis radius SR ’ By dividing the length of other parts of the image, such as n, by this ratio, the corresponding real length can be found, and the egg volume can be calculated, allowing the mass to be estimated.

[0051] The present invention has been described above by citing preferred embodiments, but the present invention is not limited to the above embodiments, and various improvements and design changes are possible within the scope of the gist of the present invention.

[0052] For example, in the above embodiment, the real length and the length in the image are compared in the same unit (millimeters), but the length in the image can be measured in pixels. Even if pixels are used as the unit, the above-described processing procedures and the method of determining the relational expressions are the same.

Claims

1. This method involves photographing eggs of unknown size being transported on a conveyor with a camera from directly above, measuring the size of the image of the egg extracted from the photograph, and determining the actual size of the egg. When the three-dimensional shape of an egg is considered to be a body of revolution, the central axis of rotation is defined as the major axis, and the radius of the countless cross-sectional circles perpendicular to the major axis is defined as the longest radius. A reference plane is set at a predetermined distance from the camera, A first relational expression is obtained in advance by placing a plurality of eggs of different sizes and having known maximum minor axis radii, or a sphere having a known radius, on a reference plane and photographing the eggs, and the first relational expression is obtained from the first relational expression to determine a second relational expression that indicates a change in the ratio of the length in the image to the real length depending on the height from the reference plane; Convert the size of the egg statue to real size based on the first and second relations. A method for measuring eggs.

2. The conveyor is a conveyor whose conveying surface is a reference surface, When the contour in the image of the egg is the contour of the egg placed on the reference plane at a height h from the reference plane, Using the relationship where height h is the real length of the maximum minor axis radius, The real length of the maximum minor axis radius calculated from the first relational expression is used as the height from the reference plane in the second relational expression to convert the size on the image into a real length.

2. The method for measuring eggs according to claim 1.

3. The conveyor is a bar conveyor that holds and transports eggs between the bars. When the outline of the egg image is the outline of the egg held between the bars at a height h from the reference plane, the interval between the bars is 2d, the real length of the maximum minor axis radius is r, and the reference plane is coincident with the imaginary plane connecting the top lines of the bars, h = (r ２ -d ２ ) １／２ Using the above relationship, we can derive the third relational expression that shows the relationship between the size of the image of the egg and the actual size of the egg from the second relational expression. The real size of the egg whose major axis is aligned with the axis of the bar is calculated using the third equation.

2. The method for measuring eggs according to claim 1.

4. This method involves photographing eggs of unknown size being transported on a conveyor with a camera from directly above, measuring the size of the image of the egg extracted from the photograph, and determining the actual size of the egg. The conveyor is a bar conveyor that holds and transports eggs between the bars. When the three-dimensional shape of the egg is considered to be a rotating body, the axis of rotation is the long axis. A table is created in advance that associates the imaged size with the real size and angle by holding a plurality of eggs or egg-shaped substitutes of different sizes, each having a known size, between the bars at different angles that the long axis of the egg or egg-shaped substitute forms with the axial direction of the bars, and photographing the eggs or egg-shaped substitutes. The real size of the egg is determined from the table by measuring the size of the image of the egg and the angle between the long axis and the axis of the bar on the image. A method for measuring eggs.

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