How to measure plant dimensions

Abstract

To provide a method for measuring plant dimensions in order to efficiently and accurately measure the dimensions of a plant.SOLUTION: A method for measuring plant dimensions, which is provided for measuring the dimensions of a plant imaged by an imager 1, comprises: arranging a background plate 3 on which dimension references are written behind the plant when the imager is used to image the plant; when imaging the dimension measurement point of the plant, changing an imaging distance only by moving an imager to carry out imaging multiple times without changing the distance between a dimension measurement point and the background plate. The dimensions of the plant are measured based on obtained values of the dimensions of the dimension measurement point in each imaging obtained by using the above dimension references of the background plate and an imaging range by the imager in each imaging.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for measuring the dimensions of a plant. [Background technology]

[0002] Conventionally, as an example of a method for measuring the dimensions of a plant, a method for measuring the diameter of a plant stem by contacting the stem with a measuring tool such as a tape measure or a vernier caliper has been implemented. However, since the plant is contacted during measurement, there is a risk of negatively affecting the vegetative growth of the plant. Furthermore, when the point where the diameter of the plant stem is to be measured is a branched part of the plant, this part becomes an obstacle, making it difficult to contact the measuring tool.

[0003] As an example of a plant-related measurement method, a system is provided in which an imaging unit captures an image of a target plant from above and measures characteristics of the plant's stem through image analysis (see, for example, Patent Document 1). By measuring plants through image analysis in this way, simple and highly accurate measurement is possible, and measurement can be performed with little or no contact with the plant.

[0004] As a method for measuring the dimensions of plants using image analysis, a method has been proposed in which a white background board marked with a black marker is placed behind the plant when the plant is imaged. However, in reality, due to the three-dimensional nature of the plant caused by the presence of branches and leaves, it is difficult to place the plant stem in close contact with the white background board, and as a result, there are cases in which measurement errors occur due to the distance between the plant stem and the white background board. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-104037 A Summary of the Invention [Problem to be solved by the invention]

[0006] Regarding the above-mentioned measurement method, in order to evaluate the degree of vegetative growth of a plant, it is conceivable to place a white background board behind the plant, take an image of the plant stem with an imaging device such as a digital camera, and measure the diameter of the plant stem using a specified image analysis program. In this case, even though there is actually a distance between the plant stem and the background board, a value is calculated assuming that the plant stem is in close contact with the white background board. For this reason, the measured value of the diameter of the plant stem using the image analysis program often exceeds the true value. In addition, it is difficult to measure the distance between the plant stem and the white background board using the image analysis program.

[0007] In view of the above-mentioned measurement error problem, the present invention aims to provide a method for measuring the dimensions of a plant by improving the method for imaging the stem of the plant and reducing the error in the measured value of the diameter of the stem of the plant. The final aim of the present invention is to enable the management of the vegetative growth of the plant based on the highly reliable measured value of the diameter of the stem of the plant.

[0008] Here, in the method for measuring the dimensions of a plant in the present invention, the parameter to be measured may be other than the diameter of the plant stem. [Means for solving the problem]

[0009] To solve the above problems, the present invention provides: A method for measuring dimensions of a plant captured by an image capture device, comprising the steps of: When the plant is imaged by the imaging device, a background board having dimensional reference marks is placed behind the plant; When imaging the dimension measurement portion of the plant, the distance between the dimension measurement portion and the background board is not changed, and the imaging distance is changed only by moving the imaging device, and the imaging is performed multiple times; The dimensions of the plant are: The measurement is performed based on the dimensions of the dimension measurement points in each image taken and the imaging range of the imaging device in each image taken, which are obtained using the dimensional reference of the background board. A method for measuring the dimensions of plants. According to the present invention, it is possible to geometrically calculate the actual dimensions of a target plant using each parameter obtained from multiple images. In addition, when an image of a part of a plant to be measured is taken, the distance between the part to be measured and the background board is not changed, and the imaging distance is changed only by moving the imager, so there is no need to consider the distance between the part to be measured and the background board, and it is possible to calculate the dimensions of the plant with higher measurement accuracy.

[0010] The present invention may also be a method for measuring the dimensions of a plant, characterized in that the measurement point of the dimensions of the plant is the diameter of the stem at a predetermined length below the growth point of the plant. This allows the measurement point to be the optimal part to be used as an index for determining whether the level of vegetative growth of the plant is appropriate or inappropriate, making it possible to obtain the state of vegetative growth of the plant with greater accuracy. In the present invention, the predetermined length may be, for example, 20 cm.

[0011] The present invention may also be a method for measuring the dimensions of a plant, characterized in that the dimension reference is a plurality of markers arranged on the white background board and the distance between them is known. In this way, in an analysis using an image analysis program, it becomes possible to calculate parameters of the dimension measurement location and the imaging range of the imaging device using the distance between the plurality of markers as a reference. In the present invention, the distance between the plurality of markers may be, for example, 30 cm.

[0012] The present invention may also be a method for measuring dimensions of a plant, characterized in that, in imaging the dimension measurement location, a frame-shaped imaging mask is displayed on the imaging screen of the imaging device, the dimension measurement location and the dimension reference are located within the frame of the frame-shaped imaging mask when imaging, and in the frame-shaped shape, the inside of the frame is brighter than the outside of the frame when imaging. This makes it easier to position the dimension measurement location when imaging the dimension measurement location, and makes it possible to prevent measurement errors caused by being too close to the edge. Effect of the Invention

[0013] According to the present invention, it is possible to measure the dimensions of a plant efficiently and with high accuracy, and it is possible to more efficiently manage the cultivation of the plant based on the obtained dimensional values. For example, in the case of measuring the diameter of a plant's stem, it is possible to more accurately determine whether the level of vegetative growth of the plant is appropriate or inappropriate from the obtained value, and to more accurately adjust the amount of water and fertilizer to be supplied. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing how an image of a plant stem is captured using an imaging device. [Diagram 2] 4 is a schematic diagram showing the characteristics of the surface of a background plate in the present invention. FIG. [Diagram 3] FIG. 13 is a schematic diagram showing how, in the present invention, the distance between the plant stem and the background board is not changed, and the imaging distance is changed only by moving the camera, and two images are captured. [Figure 4] FIG. 1 is a schematic diagram showing how the diameter of a plant stem is measured using an image analysis program after imaging in the present invention. [Diagram 5] 1 is a schematic diagram showing an imaging mask in an imaging screen seen by a measurer when an image of a plant stem and a background board is captured by an imaging device in the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [Application example] In this application example, a method for measuring the diameter of a plant stem will be described as an example of a method for measuring the dimensions of a plant. In measuring the diameter of a plant stem, in order to obtain more accurate information on the position coordinates of the target measurement point, there is a method in which a white background board on which markers whose distances from each other are known are placed behind the plant stem. With the background board placed behind the plant stem to be measured, the plant stem and the background board are imaged, and in analyzing the image, it is possible to calculate the diameter of the plant stem in the image based on the distance between the markers on the white background board.

[0016] However, in reality, when imaging a plant stem with an imaging device, it is difficult to bring the plant stem into close contact with a white background plate due to the three-dimensional nature of the plant's growing point caused by the presence of branches and leaves, but the plant stem is imaged as being in close contact with the white background plate. Thus, in measuring the diameter of a plant stem, a measurement error occurs due to the distance between the plant stem and the white background plate, and the measured value of the diameter of the plant stem is larger than the true value.

[0017] In order to eliminate measurement errors caused by the distance between the plant stem and the white background plate, when imaging the plant stem, the distance between the plant stem and the white background plate is not changed, and the imaging distance is changed only by moving the imaging device, and imaging is performed twice.

[0018] When analyzing the captured images, the top end of the plant stem is taken as the growth point of the target plant, and the diameter of the stem is measured, for example, 20 cm below the growth point. The stem diameter is calculated by a geometric calculation using the stem diameters obtained in each of the two captures as parameters. All of these parameters are calculated using markers on the background board as reference points.

[0019] [Example] Hereinafter, a method for measuring the size of a plant according to an embodiment of the present invention will be described in detail with reference to the drawings. In the following, the measurement of the size of a plant will be described as an example of measuring the diameter of a stem of a plant. In addition, the following example is merely one example of the method for measuring the size of a plant according to the present invention, and is not intended to limit the object of the size measurement or the procedure used in the size measurement.

[0020] <Dimensional measurement method> FIG. 1 is a schematic diagram showing how a plant stem 2 is imaged using an imaging device 1. For example, a digital camera is often used as the imaging device 1. FIG. 2 is a schematic diagram showing the surface characteristics of the background board 3 shown in FIG. 1. The background board 3 is often white. The plant stem 2 is imaged using the imaging device 1 with the background board 3 placed behind it, and the measurement point is identified by image analysis, and the diameter of that part is measured. When imaging the plant stem 2, it is ideal for the plant stem 2 to be in close contact with the background board 3 behind it, but in reality, due to the three-dimensional nature of the plant's growing point caused by the presence of branches and leaves, a distance of H2 is generated between the plant stem 2 and the background board 3. Here, the growing point of the plant refers to the part at the tip of the plant stem where cell division is active.

[0021] As shown in Figure 1, the true value of the diameter of the plant stem 2 is D1, but because the diameter of the plant stem 2 is measured assuming that the plant stem 2 is in close contact with the background board 3, the measured value of the diameter of the plant stem 2 is D2. Since D2 is greater than D1, the measured value of the diameter of the plant stem 2 exceeds the true value. When capturing an image, D1 can be calculated if H1, which is the distance between the camera 1 and the plant stem 2, is known, but H2 and H3, which is the distance between the camera 1 and the background board 3, are not known. Since it is difficult to measure H3, it is difficult to calculate H1, which is the difference between H3 and H2. A method is required to eliminate this measurement error in measuring the diameter of the stem 2 of a plant.

[0022] Measurement of dimensions such as the diameter of the plant stem 2 is performed using a captured image with a background plate 3 shown in Fig. 2. The background plate 3 has marker areas 4 in two locations, the upper right and the upper left in the orientation of Fig. 2, and each of the marker areas 4 has multiple markers 5. The orientation of the background plate 3 up and down during imaging does not matter. Here, the markers 5 correspond to the dimensional reference in the present invention.

[0023] In an image of a plant stem 2 captured with a background board 3 placed behind it, the reference position coordinates of the multiple markers 5 are determined in advance, and it is possible to measure the diameter of the plant stem 2 from the number of pixels between the multiple markers 5 on the image and the number of pixels in the width of the target plant stem 2. The shape of the markers 5 is often a circle filled with black. Furthermore, it is sufficient to have at least one marker 5 in each of the two marker areas 4. When capturing an image using the imaging device 1, the marker area 4 is made to fit completely within the capturing range. Furthermore, when capturing an image, care is taken to ensure that no shadows overlap the marker area 4.

[0024] The background board 3 also has a measurement line 6, which can be used to measure, for example, the width of a plant leaf. Note that the solid lines that intersect vertically in the vertical and horizontal directions on the background board 3 shown in Figure 2 are all measurement lines, and scales are actually displayed to aid in dimensional measurement, but these are omitted in Figure 2. When capturing an image of the plant stem 2, it is positioned so that it is within a measurement area 7 enclosed and indicated by a dotted line. Because the measurement line 6 and the plant stem 2 are almost parallel to each other when capturing an image, it is possible to determine the approximate distance from the top of the plant to the part whose diameter is to be measured.

[0025] Next, when imaging a plant stem 2 using the imaging device 1, the background plate 3 shown in Fig. 2 is placed behind the plant stem 2, and when imaging, the distance between the plant stem 2 and the background plate 3 is not changed, but the imaging distance is changed only by moving the imaging device 1, and imaging is performed twice while changing the imaging distance. A method for measuring the diameter of the plant stem 2 using the image obtained in this manner will be described.

[0026] FIG. 3 is a schematic diagram showing how two images are taken by changing the imaging distance only by moving the imaging device 1 without changing the distance between the plant stem 2 and the background board 3. FIG. 3(a) shows a simplified diagram of the positional relationship of the imaging device 1, the plant stem 2, and the background board 3 in the two images taken from above. In the two images taken, the position of the imaging device 1 when the plant stem 2 is imaged from a distance is defined as position1, and the position of the imaging device 1 when the plant stem 2 is imaged from a close distance is defined as position2. In addition, the imaging range obtained based on the distance between the markers 5 at position1 is defined as x1, the diameter of the plant stem 2 obtained in the same manner is defined as d1, the imaging range obtained based on the distance between the markers 5 at position2 is defined as x2, and the diameter of the plant stem 2 obtained in the same manner is defined as d2. Here, the imaging range refers to the width of the image in the analysis using an image analysis program.

[0027] The true diameter d0 of the plant stem 2 can be calculated by a geometric calculation using x1, x2, d1, and d2. d0 can be expressed by the formula (1).

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[0028] FIG. 3(b) shows simplified diagrams of the images of the plant and the background board 3 captured by the image capture device 1 at each of position 1 and position 2. Here, the diameter of the plant stem 2 in each image is measured from the distance between the markers 5 on the background board 3 in the images captured at each podition and the width of the target plant stem 2. In practice, the distance between the markers 5 on the background board 3 in the images captured by the image capture device 1 may be obtained as the number of pixels present between the pixels corresponding to the centers of the markers 5 on the image. The width of the plant stem 2 may be obtained as the number of pixels present between the pixels corresponding to both ends of the stem 2 in the horizontal direction. The distance between the markers 5, indicated as W in FIG. 3(b), is, for example, 30 cm. Note that when capturing an image, the plant does not need to be located in the center as long as the background board 3 is within the capture range, and the image may be captured at an angle.

[0029] FIG. 4 is a schematic diagram showing how the diameter of the plant stem 2 is measured using a predetermined image analysis program after imaging. Here, the background board 3 is shown simply. Here, the image analysis program is a program prepared for calculating the diameter of the plant stem 2 at the dimension measurement point from an image including the plant stem 2 and the background board 3 captured by the imaging device 1. The image analysis program may be loaded into a general PC (not shown), stored in a memory such as a ROM of the PC, and executed by the CPU of the PC. If the imaging device 1 is a general digital camera, the image captured by the imaging device 1 is imported into the PC, and the image is called and analyzed by the image analysis program. If the imaging device 1 is, for example, a smartphone or a tablet PC, the image analysis program may also be loaded into the smartphone or tablet PC, and the image may be analyzed as it is after imaging. In the image analysis program, when the image of the plant is traced downward from the top end of the plant in the direction of the plant stem 2, the traced trajectory is displayed on the image. The traced trajectory is displayed as a thick line as shown in FIG. 4(a). The starting point of the traced trajectory is recognized as the growing point of the plant, and the measurement point for the diameter of the plant stem 2 is 20 cm below the growing point. L represents the length along the direction of the plant stem 2 downward from the growing point, and does not represent the vertical distance downward from the growing point.

[0030] As shown in FIG. 4(b), in the analysis using the image analysis program, a graph is output with the value of L on the horizontal axis and the value of the stem diameter on the vertical axis. Generally, plant stems tend to become thicker toward the bottom, and as shown in FIG. 4(b), the larger the value of L, the larger the value of the stem diameter. In measuring the stem diameter, when tracing the plant stem on the image as shown in FIG. 4(a), the stem width is calculated at each point of the traced trajectory according to the value of L. The stem width at each point is determined based on the distance between the markers 5 on the background board 3, and the determined width value is regarded as the stem diameter at each point.

[0031] Note that during imaging, the stem 2 of the plant may overlap with the branches and leaves of the plant, and in the analysis, the stem 2 of the overlapping part of the plant may not be recognized, and the continuous stem 2 of the plant may be recognized as being interrupted. Therefore, in the image analysis program of this embodiment, among the curves at the ends of the stems obtained by imaging, it is possible to later complement a straight line or a spline curve for the interrupted part. In this way, in the image analysis, it is possible to recognize the stem 2 of the plant as being continuous. In FIG. 4(b), the diameter of the stem 2 when L = 20 is taken as the measured value of the diameter of the stem 2 of the plant.

[0032] FIG. 5 is a schematic diagram showing an imaging mask 8 in the imaging screen seen by the measurer when the imaging device 1 images the stem 2 of the plant and the background plate 3. The background plate 3 is shown schematically. When imaging the stem 2 of the plant, the stem 2 of the plant needs to enter the measurement area 7 shown in FIG. 2 on the background plate 3. In the imaging screen, it is important to align the position of the stem 2 of the plant. Therefore, in order to facilitate this, a double-character "king" - shaped imaging mask 8 is displayed. Although shown schematically in FIG. 5, only the inside of the frame of the imaging mask 8 is bright, and the outside of the frame is shaded and not clearly visible to the imager. It is a necessary condition during imaging that the stem 2 of the plant and the marker area 4 are within the frame of the imaging mask 8. In this embodiment, in this way, when imaging by the imaging device 1, the imaging mask 8 is displayed on the imaging screen seen by the measurer, and by arranging the stem 2 of the plant and the marker area 4 within its frame, the positional relationship between the stem 2 of the plant and the background plate 3 can be easily determined, and the measurement accuracy of the diameter of the stem 2 of the plant can be improved. Note that the imaging mask 8 is only a tool for facilitating the alignment of the position of the stem 2 of the plant and is not essential in the imaging screen. Also, the shape of the imaging mask 8 does not have to be "king" - shaped as long as the stem 2 of the plant and the marker area 4 can be placed within its frame. For example, it may be "T" - shaped. Also, it does not have to be in the shape of a character such as a "+" shape.

[0033] The dimension measurement method shown in this embodiment makes it possible to measure the diameter of a plant stem 2 with high accuracy, with almost no contact with the plant stem 2, except for contact for fixing the plant stem 2. Specifically, the measurement accuracy can be controlled to within an error of 1 mm of the absolute value from the true value. Generally, it is necessary for a plant to achieve an optimal growth balance at each growth stage, and the measurement of the diameter of the plant stem 2 is one of the indices for managing the nutritional growth required for growth balance.

[0034] In the following, the components of the present invention will be described with reference to the reference numerals in the drawings in order to make it possible to compare the components of the present invention with the configurations of the embodiments. <Invention 1> A method for measuring the dimensions of a plant captured by an image capture device (1), comprising the steps of: When the plant is imaged by the imaging device, a background plate (3) having dimensional standards (5) marked thereon is placed behind the plant; When imaging the dimension measurement portion of the plant, the distance between the dimension measurement portion and the background board is not changed, and the imaging distance is changed only by moving the imaging device, and the plant is imaged multiple times; The dimensions of the plant are: The measurement is performed based on the dimensions of the dimension measurement points in each image taken and the imaging range of the imaging device in each image taken, which are obtained using the dimensional reference of the background board. How to measure plant dimensions. [Explanation of symbols]

[0035] 1: Camera 2: Plant stem 3:Background board 4: Marker area 5: Marker 6: Survey line 7: Measurement area 8: Image capture mask

Claims

1. A method for measuring dimensions of a plant captured by an image capture device, comprising the steps of: When the plant is imaged by the imaging device, a background board having dimensional reference marks is placed behind the plant; When imaging the dimension measurement portion of the plant, the distance between the dimension measurement portion and the background board is not changed, and the imaging distance is changed only by moving the imaging device, and the imaging is performed multiple times; The size of the plant The measurement is performed by calculating using, as parameters, an acquired value of the dimension of the dimension measurement location obtained by using a standard of the dimension of the background board in each of the images acquired by the multiple images, and a value indicating an imaging range by the imaging device obtained by using a standard of the dimension of the background board in each of the images acquired by the multiple images. How to measure plant dimensions.

2. The dimension measurement point of the plant is a diameter of a stem at a predetermined length below a growth point of the plant. The method for measuring dimensions of a plant according to claim 1.

3. The dimensional reference is a plurality of markers arranged on the white background plate at known distances from each other. The method for measuring the dimensions of a plant according to claim 1 or 2.

4. displaying a frame-shaped imaging mask on an imaging screen of the imaging device in imaging the dimension measurement location; and determining a positional relationship between the dimension measurement location and the dimension reference by arranging the dimension measurement location and the dimension reference at a predetermined position inside the imaging mask on an imaging screen of the imaging device during imaging. A method for measuring dimensions of a plant according to any one of claims 1 to 3.

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