Water content measurement device and water content measurement method for lumber

Abstract

To provide a water content measurement device capable of measuring water content of lumber having various shapes.SOLUTION: A water content measurement device includes: a mass measurement part for measuring the mass of lumber stored in a container; an imaging part for imaging the lumber; and a calculation processing part for acquiring the volume of the lumber based on the actual volume ratio of the lumber that can be acquired from an apparent volume of the lumber stored in the container and image data captured by the imaging part, and for calculating the water content in the lumber, based on the volume, measured mass, and fully dried density information corresponding to the tree type of the lumber.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a moisture content measuring device and a moisture content measuring method for measuring the moisture content (moisture content) of wood of various shapes. [Background technology]

[0002] Known methods for measuring the moisture content or amount of moisture in wood include high-frequency measurement methods and microwave transmission measurement methods. The high-frequency measurement method determines the moisture content (moisture content) of wood by applying a high-frequency electric field to the wood and measuring its dielectric constant. The microwave transmission measurement method measures the moisture content (moisture content) of wood by transmitting microwaves through the wood and measuring the amount of attenuation.

[0003] Patent Document 1 also discloses a method for determining the moisture content (amount of moisture) of green wood by measuring the weight of the green wood and measuring its volume from the length and diameter of the butt section, photographing the butt section, and comparing the dry density data corresponding to the sample image data that most closely resembles the image data with the actual density of the green wood determined from the measured weight and volume. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-49178 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the high-frequency measuring method has a measurement range limited to the vicinity of the surface of the wood (about 2 to 3 mm from the surface), and cannot measure the moisture content of the entire wood to be measured, and can only measure very thin wood. In addition, the microwave transmission measuring method requires shape information of the wood to be measured, and there is a risk of measurement accuracy decreasing for shapes with different thicknesses, so the shape of the wood to be measured is limited. Furthermore, the measuring method of Patent Document 1 measures only wood of a specific shape, such as a log with a butt end, and does not measure wood of other shapes. In addition, a halogen moisture meter has been put into practical use, which uses a halogen heater (infrared rays) to heat and dry a sample of the wood to be measured, and measures the moisture content from the mass difference before and after drying. However, moisture content measurement using a halogen moisture meter requires a relatively long time because it includes a drying process by heating. Some products are equipped with a mode that completes the measurement in a short time, but a significant decrease in measurement accuracy is unavoidable. In addition, the size of the sample used for measurement using a halogen moisture meter generally needs to be small, so it is difficult to grasp the moisture content of the entire sample of a relatively large size with one halogen moisture meter.

[0006] The present inventors have actively conducted research and development into technology for measuring the moisture content of wood that is not dependent on the shape of the wood, in particular, measurement of the moisture content of aggregates of wood chips, and have now developed a new moisture content measurement technology that does not limit the range of shapes of wood that can be measured.

[0007] Therefore, an object of the present invention is to provide a moisture content measuring device and a moisture content measuring method that can measure the moisture content of wood of various shapes, and a moisture content measuring device and a moisture content measuring method that can measure the moisture content of wood easily and quickly. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the moisture content measuring device of the present invention is characterized in that it comprises a mass measuring unit that measures the mass of wood placed in a container, an imaging unit that images the wood, and a calculation processing unit that calculates the volume of the wood based on the apparent volume of the wood placed in the container and an actual volume ratio of the wood that is calculated from image data captured by the imaging unit, and calculates the moisture content contained in the wood based on the volume, the mass, and whole dry density information corresponding to the species of the wood.

[0009] The moisture content measuring method of the present invention is characterized by comprising a mass measuring step of measuring the mass of wood contained in a container, an imaging step of imaging the wood, and a calculation step of calculating the volume of the wood based on the apparent volume of the wood contained in the container and the actual volume ratio of the wood determined from the image data captured in the imaging step, and calculating the moisture content contained in the wood based on the volume, the mass, and total dry density information corresponding to the wood species. Further details and advantageous examples of the present invention will be apparent from the exemplary embodiments of the present invention described below. Effect of the Invention

[0010] According to the wood moisture content measuring device and method of the present invention, the moisture content (moisture content) of wood of various shapes can be measured simply and quickly. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing an example of the configuration of a moisture content measuring device for wood in an embodiment of the present invention; [Diagram 2] FIG. 13 is a diagram showing an example of the arrangement of an imaging unit and a container. [Diagram 3] 4 is a flowchart of a moisture content measurement process for wood according to an embodiment of the present invention. [Figure 4] FIG. 1 shows a container 11 containing wood chips. [Diagram 5] 1 is a diagram showing an example of image data of wood chips captured by an imaging unit 14. FIG. [Figure 6]1 is a diagram showing an example of binary image data obtained by binarizing image data; [Figure 7] FIG. 1 is a graph showing a comparison between the actual volume and moisture content determined by the moisture content measurement process of the present invention and the actual volume and moisture content determined by the total drying method. [Figure 8] 11 is a graph showing an example of the relationship between the brightness threshold value obtained by the brightness threshold value determination method and the average brightness value of each image data. [Figure 9] FIG. 1 is a graph showing a comparison between the moisture content measured by the moisture content measurement process of the present invention and the moisture content measured by the complete drying method when the constants A and B are set to arbitrary values. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention. An embodiment of the present invention will be described with reference to specific drawings.

[0013] 1 is a diagram showing an example of the configuration of a moisture content measuring device for wood in an embodiment of the present invention. The moisture content measuring device 10 is configured to include a mass measuring unit 12 that measures the mass of a piece of wood 20 contained in a container 11, an imaging unit 14 that images the piece of wood 20 contained in the container 11, and an arithmetic processing unit 16 that performs image analysis of image data captured by the imaging unit 14, obtains the volume of the piece of wood by numerically calculating the apparent volume of the piece of wood 20 in the container 11 and the actual volume ratio (volume ratio) of the apparent volume obtained by the image analysis, and calculates the moisture content of the piece of wood 20 based on the obtained volume and mass. Note that the mass measuring unit 12 and the imaging unit 14 are not limited to data transfer means by wired or wireless communication and data transfer means using a data recording medium, and the communication standards and standards of the data recording medium, etc., in the method of outputting data to the arithmetic processing unit 16, and in some cases, the user may directly input data to the arithmetic processing unit 16.

[0014] The wood 20 to be measured is wood that has been processed to a size that can be stored in the container 11, and wood 20 of various shapes and forms, such as raw wood such as logs, timber, planks, or aggregates of wood chips, can be measured. The size of the container 11 is set to a dimension that can accommodate the wood 20 to be measured, and is not restricted in size as long as it is within a practicable range. For example, if the wood 20 to be measured is a batch size (approximately 1 m) stored in a flexi-con bag, 3 ), the container 11 must be sized to accommodate it, and the mass measuring unit 12 and the imaging unit 14 must also be optimized. In the following embodiment, a measurement process will be described in which the measurement target wood 20 is an aggregate of wood chips, the volume of which is not particularly easy to determine.

[0015] In order to capture an image of the wooden piece 20 in the container 11 from outside the container 11 with the imaging unit 14, the container 11 is a transparent case made of glass, acrylic resin, or the like, and is preferably rectangular, but may be another container shape such as a cylinder. The mass measuring unit 12 is, for example, a scale with a flat table, and the container 11 containing the wooden piece 20 is placed on the table of the mass measuring unit 12, and the mass of the wooden piece 20 in the container 11 is measured.

[0016] The imaging unit 14 is an imaging means such as a digital camera or scanner that captures the wood 20 in the container 11, and the arithmetic processing unit 16 is a computer device that performs image analysis processing on the image data of the wood 20 captured by the imaging unit 14. The arithmetic processing unit 16 acquires the shape and three-dimensional size of the wood 20, the area occupied by the wood 20 in the container 11, etc. from the image data captured by the imaging unit 14, calculates the actual volume ratio of the wood 20, and calculates the volume of the wood 20 together with the apparent volume of the wood 20. In the embodiment described below, image analysis processing was performed through a GUI application implemented in Python using a tool that utilizes various algorithms of OpenCV, an image processing library. The arithmetic processing unit 16 stores and holds information data on the known total dry density of the wood 20 for each tree species. The total dry density of wood is density data of wood in a total dry state without water for each tree species.

[0017] FIG. 2 is a diagram showing a schematic arrangement example of the imaging unit 14 and the container 11. The container 11 is shown as viewed from above, and the imaging unit 14 images the wood 20 from different angles. As shown in FIG. 2, for example, multiple imaging units 14 are arranged facing multiple side surfaces of the rectangular parallelepiped container 11, and each imaging unit 14 images the wood 20 in the container 11. Alternatively, one imaging unit 14 may be installed movably to image the wood 20 from multiple side surfaces of the container 11. Furthermore, the imaging unit 14 may be arranged above the container 11 and image the wood 20 from above. Note that the volume of the wood 20 can be calculated by image analysis of one image data captured by the imaging unit 14 from one direction, but it is preferable to obtain multiple image data captured from different angles in order to calculate the volume with higher accuracy. In addition, in the case of a digital camera, the imaging unit 14 is arranged at a position spaced apart from the side surface of the container 11 so as to be able to capture the side surface of the container 11, and in the case of a scanner device, the imaging unit 14 is attached so as to be able to scan the side surface of the container 11.

[0018] 3 is a flow chart of a moisture content measurement process for wood in an embodiment of the present invention. The container 11 containing the wood 20 is placed on the mass measurement unit 12, and the mass of the wood 20 is measured (S100). The apparent volume of the wood 20 contained in the container 11 is obtained (S102). The apparent volume is the apparent volume of the area occupied by the wood in the container 11, and is calculated by multiplying the bottom area of ​​the container 11 by the height dimension of the wood 20. The imaging unit 14 images the wood 20 in the container 11 and obtains image data of the wood 20 (S104). The calculation processing unit 16 analyzes the obtained image data, obtains an actual volume ratio, which is the ratio of the area actually occupied by the wood 20 in the container 11, and calculates the volume of the wood 20 from the apparent volume and actual volume ratio obtained in S102 (S106). Furthermore, the calculation processing unit 16 calculates the moisture content of the wooden piece 20 based on the mass of the wooden piece 20 measured in S100, the volume of the wooden piece 20 determined in S104, and the dry density information corresponding to the species of the wooden piece 20 (S108).

[0019] The moisture content of wood is calculated using the following formula (1). Moisture content (%) = (mass - total dry density x volume) / (total dry density x volume) x 100 (1) When the wooden piece 20 is an aggregate of wood chips, the volume of the wooden piece used in the calculation of the moisture content is the volume of the space occupied by the wood chips contained in the container 11 (actual volume), and the actual volume of the wood chips, which is the volume of the space occupied only by the wood chips, is obtained by image analysis processing from the apparent volume of the wood chips contained in the container 11 with many gaps. The outline of the image analysis processing is to extract the area of ​​the wood chips in the image data by binarizing the image data captured by the imaging unit 14, to obtain the ratio of the area that the wood chips actually occupy in the container 11 (actual volume ratio), and to calculate the actual volume of the wood chips contained in the container 11 based on the apparent volume and actual volume ratio of the wood chips.

[0020] <Example of moisture content measurement> Hereinafter, a specific embodiment will be described, particularly with regard to the moisture content measurement process according to the present invention described above and shown in Fig. 3, in which the actual volume of an aggregate of wood chips contained in a container 11 is calculated by image analysis processing, and the moisture content is measured from a numerical calculation of the known total dry density and the measured mass. As wood chip samples (length about 10 mm / thickness about 2 mm) for moisture content measurement, a number of samples with different moisture states shown in Table 1 below were prepared. Cedar was used as the wood chip species. The total dry density of cedar is 0.35 g / cm 3 (Reference: Ishimaru, Y.; Yoshida, Y.; Sugiyama, M., Physics of Wood [Wood Science Lectures], Kaiseisha, 2017 [page 37].) The wood chips to be used as samples were soaked in tap water in advance to make them saturated with water, and then dried under the different drying conditions shown in Table 1 to create samples No. 1 to No. 5 with different moisture contents.

[0021] [Table 1]

[0022] In addition, the moisture content of each sample was measured by the moisture content measurement process according to the present embodiment, and the moisture content was measured using the total drying method defined in the Japanese Agricultural Standards (JAS). The total drying method involves drying the wood in a hot air drying oven at 105°C for a sufficient period of time, and calculating the moisture content from the mass of the wood after drying (total dry mass) in a state where all moisture has been removed, using the following formula (2). Moisture content (%) = (mass before drying - mass after drying) / mass after drying x 100 (2)

[0023] Table 2 below shows the results of moisture content measurements using the total drying method.

[0024] [Table 2]

[0025] The "theoretical actual volume" in Table 2 will be described later in the section on determining the brightness threshold. In this embodiment, the moisture content determined by the complete drying method is regarded as the accurate moisture content, and will be compared with the moisture content determined by the moisture content measurement process according to the present invention, as described later.

[0026] FIG. 4 is a diagram showing a container 11 containing wood chips. Sample wood (wood chips) 20 are placed in the container 11 up to a predetermined height. Marking lines may be drawn on the container 11 to keep the height constant. The container 11 has a rectangular parallelepiped shape, and the apparent volume of the wood chips is determined from the dimensions of the container 11 by visually placing wood chips in the container up to a predetermined height. The dimensions (inner dimensions) of the container 11 used in this example are width 204 mm × length 204 mm × height 202 mm, and the predetermined height is 150 mm from the inner bottom surface, giving an apparent volume of 6242 cm. 3 The apparent volume of the wood 20 is stored and held in advance in the calculation processing unit 16 according to the measurement conditions, or the value is input to the calculation processing unit 16 each time a measurement is made. The mass of the wood chips contained in the container 11 is measured using a weighing machine (in this embodiment, an SJ-5000 manufactured by A&D is used).

[0027] FIG. 5 is a diagram showing an example of image data of wood chips captured by the imaging unit 14. In this embodiment, both the imaging unit 14 of a digital camera (in this embodiment, a smartphone SOV42-u manufactured by Sony Corporation is used) and a scanner device (in this embodiment, a PSC-HS2BK manufactured by Sanwa Supply Co., Ltd. is used) were used to capture images of each sample. In this embodiment, the resolution of the digital camera is 4032×1728, and the resolution of the scanner device is 8752×14501, and images were captured in 8-bit color JPEG, and parts not required for image analysis processing (parts other than the wood 20) were trimmed. Trimming is performed arbitrarily or within a range specified in advance each time, and it is desirable that the image after trimming does not include anything other than the wood 20 visible through the container 11. More preferably, in order to avoid a decrease in the accuracy of the image analysis processing, if there is a part where the wood 20 cannot be clearly captured due to condensation or the like generated on the inner surface of the container 11, the part is outside the measurement range of trimming. The image data shown in FIG. 5 is image data captured by a scanner device of Sample No. 4. An example of calculating the actual volume and moisture content of wood chips by image analysis processing of the image data shown in FIG. 5 will be described below.

[0028] Image data 1 to 4 in FIG. 5 are examples of grayscale images captured from the four side surfaces of the container 11. In the case of color imaging, the image data is grayscaled, for example, in 256 gradations (8 bits). A grayscale image is obtained by converting the RGB values ​​of the image data into luminance values. The conversion from the RGB values ​​of the image data to luminance is performed according to the following conversion formula (3) described in ITU-R BT.601 (the calculated value is rounded off to the first decimal place, and the luminance Y is output as an integer value). Luminance Y=0.229*R+0.587*G+0.114*B (3)

[0029] The grayscaled image data is binarized using a predetermined brightness threshold to extract the wood chip area and calculate the actual volume of the wood chip. The average brightness value for each of the image data 1 to 4 and the average brightness value for all four image data (sometimes referred to as the four-side average brightness value to distinguish it from the average brightness value of one image data) are calculated. The average brightness value is the average brightness value of all pixels in one image data to be analyzed. The average brightness values ​​of the image data of the wood chips are shown in Table 3 below.

[0030] [Table 3]

[0031] The brightness threshold for the binarization process is determined according to the average brightness value of the image data (including the average brightness value of four sides). Since the variation in calculation error can be reduced by averaging the brightness values ​​of a plurality of image data obtained by capturing images of different sides, the average brightness value of four sides is used to determine the brightness threshold in this embodiment, but it is also possible to use the average brightness value of one image data. The brightness threshold is variably set according to the magnitude of the average brightness value of the image data, and the method of determining the brightness threshold will be described later.

[0032] Fig. 6 is a diagram showing an example of binary image data. Image data 1 to 4 are subjected to a binary processing using a determined brightness threshold value to generate binary image data. Through the binary processing, when the brightness is equal to or less than the brightness threshold value, pixels are converted to black, and when the brightness is greater than the brightness threshold value, pixels are converted to white, and binary image data is generated. The white areas in Fig. 6 are the areas occupied by wood chips.

[0033] The ratio of white area in the binarized image data is calculated. This white area ratio is a two-dimensional area ratio, and to convert it to a three-dimensional area ratio, the white area ratio (area ratio) is raised to the power of 3 / 2 to convert it to a three-dimensional area ratio (volume ratio). The calculated three-dimensional area ratio is the actual volume ratio, which is the ratio of the actual area occupied by the wood chips in the container 11, and as shown in equation (4), the actual volume of the wood chips (estimated actual volume) shown in Table 4 below is calculated by multiplying the apparent volume by the actual volume ratio. Actual volume = apparent volume × actual volume ratio (4)

[0034] [Table 4]

[0035] Furthermore, using the actual volume shown in Table 4 above, the moisture content of the wood chips shown in Table 5 below is calculated from the above formula (1).

[0036] [Table 5]

[0037] Table 6 below shows the measurement results of this embodiment, and shows the actual volume (referred to as "analyzed actual volume" in Table 6 below) and numerical data of moisture content calculated by the moisture content measurement process of the present invention for each of Sample No. 1 to Sample No. 5 using two types of imaging units, a camera and a scanner device.

[0038] [Table 6]

[0039] FIG. 7 is a diagram showing a comparison between the actual volume and moisture content obtained by the moisture content measurement process of the present invention and the actual volume and moisture content obtained by the total drying method, and was created by extracting the numerical data of Tables 2 and 6 above. FIG. 7(a) shows the numerical data of the actual volume and moisture content calculated by the moisture content measurement process of the present invention in each case using two types of imaging units, a camera and a scanner device, and the numerical data of the actual volume and moisture content obtained by the total drying method in a table, and FIG. 7(b) is a diagram showing the numerical data of the moisture content in FIG. 7(a) in a graph. According to the graph of FIG. 7(b), the moisture content x obtained by the moisture content measurement process of the present invention shown on the horizontal axis (X axis) and the moisture content y by the total drying method shown on the vertical axis (Y axis) can be substantially approximated by a straight line close to y=x, so it can be understood that the two values ​​are very close. In addition, the following Table 7 shows the minimum and maximum difference in moisture content.

[0040] [Table 7]

[0041] The moisture content determined by the moisture content measurement process of the present invention is within a difference range of about ±15% compared to the completely dry method, and this difference range has been confirmed to be sufficiently practical that the moisture content measurement process of the present invention can replace measurement by the completely dry method.

[0042] <How to determine the brightness threshold> As described above, the brightness threshold value set for the binarization process is variably set according to the magnitude of the average brightness value of the image data. Here, the inventors of the present application have found that the brightness threshold value that results in the actual volume (analytical actual volume) of the wood chips closest to the theoretical actual volume of the wood chips corresponding to the moisture content obtained by the total drying method is linearly proportional to the average brightness value. In other words, the relationship between the brightness threshold value and the average brightness value can be expressed by the following formula (5). Brightness threshold y = A × average brightness x + B (5) A and B are constants, and can be calculated, for example, by a luminance threshold derivation procedure described later.

[0043] Since wood tends to be darker in color as its moisture content increases, the higher the moisture content of wood of the same species, the lower the brightness value of its image data, and it is understood that a more accurate actual volume can be obtained by setting the brightness threshold value according to the average brightness value of the image data. The relationship between the brightness threshold value and the average brightness value of the image data is obtained in advance by the following brightness threshold value derivation procedure. (1) For samples No. 1 to No. 5, the theoretical actual volume of wood chips corresponding to the moisture content determined by the total drying method is calculated. The theoretical actual volume of wood chips corresponding to the moisture content determined by the total drying method is given by the following formula (6). Theoretical volume = total dry mass / total dry density (6) (2) When binarizing each image data of Sample No. 1 to Sample No. 5, a brightness threshold is determined at which the actual volume (analyzed actual volume) calculated by the water content measurement process of the present invention described above is closest to the theoretical actual volume. (3) For samples No. 1 to No. 5, the brightness threshold value obtained in (2) and the average brightness value of each image data are plotted, and the relational expression of formula (5) is generated using, for example, the least squares method.

[0044] FIG. 8 is a graph showing an example of the relationship between the luminance threshold value obtained by the above-mentioned luminance threshold value determination method and the average luminance value of each image data, and shows that the luminance threshold value and the average luminance value of the image data are in a proportional relationship defined by formula (5). It is desirable that formula (5) used to determine the luminance threshold value has been derived in advance through prior experiments, and ideally, it is desirable to obtain data using the same imaging device and imaging conditions as those used in actual measurements, and using samples that can be considered to be part of the same supply chain in terms of the species, place of origin, shape processing history, etc. of the wood to be measured. In the present embodiment of FIG. 8, the constants A and B are, when a digital camera or a scanner device, respectively, is used for the imaging unit 14, In the case of image data captured by a scanner, A=1.1767, B=-6.5205 In the case of image data captured by a digital camera, A=1.0977, B=-3.1653 The integer value obtained by substituting the average luminance value x into equation (5) and discarding the decimal point of the value obtained is used as the luminance threshold value y that is set for the binarization process.

[0045] The constants A and B in the above formula (5) for determining the brightness threshold can be found by the above procedure, but as an alternative procedure, predetermined fixed constants A and B may be given. In this case, the constants A and B are set to arbitrary values, and if the arbitrary values ​​of the constants A and B differ from the values ​​of the constants A and B found by the above procedure, the brightness threshold will shift, and the actual volume (analyzed actual volume) found by the binarization process will also differ from the theoretical actual volume in the total drying method. However, by carrying out a mathematical correction process, it is possible to approximate the moisture content value by the total drying method.

[0046] Fig. 9 is a graph showing the numerical data of the moisture content calculated by the moisture content measurement process of the present invention and the numerical data of the moisture content calculated by the total drying method when the constants A and B are set to arbitrary values. Fig. 9(a) is the graph before the correction process, and Fig. 9(b) is the graph after the correction process. In Fig. 9, the constants A and B are set to arbitrary values ​​of A=1.2 and B=0.

[0047] In FIG. 9, as in the graph of FIG. 7(b), if the horizontal axis (X axis) is the moisture content x obtained by the moisture content measurement process of the present invention and the vertical axis (Y axis) is the moisture content y obtained by the complete drying method, the straight lines L1 and L2 showing the relationship between the two moisture contents before the correction process shown in FIG. 9(a) are significantly deviated from the dotted line y=x, and it can be understood that the difference between the two moisture contents is relatively large. By performing a mathematical correction process to bring the straight lines L1 and L2 showing the relationship between the two moisture contents before the correction process closer to the straight line y=x, the two moisture contents can be approximated as shown in FIG. 9(b). Specifically, the x values ​​of each plot are converted to values ​​obtained by substituting the straight lines L1 and L2. It is desirable that the straight lines L1 and L2 used to determine the brightness threshold value are derived in advance by prior experiments, and ideally, it is desirable to obtain data using the imaging device and imaging conditions used in the actual measurement, and using samples that can be considered to be part of the same supply chain in terms of the species, place of origin, shape processing history, etc. of the wood to be measured. Table 8 below shows the minimum and maximum differences between the moisture content measured by the moisture content measurement process of the present invention and the moisture content measured by the complete drying method, which were determined by carrying out the correction process.

[0048] [Table 8]

[0049] In this way, the moisture content determined by the moisture content measurement process of the present invention, which includes a procedure of setting the constants A and B for determining the brightness threshold to arbitrary values ​​and then correcting the moisture content by the above-mentioned correction process, was determined to have a difference within a range of approximately ±15% compared to the total drying method, as in the case of Table 7 above, confirming that moisture content can be measured with high accuracy.

[0050] According to this embodiment, the wooden piece 20 stored in the container 11 is imaged by the imaging unit 14, and the image data is subjected to image analysis to determine the actual volume ratio, which is the ratio of the area that the wooden piece 20 actually occupies in the container 11, and the volume (actual volume) of the wooden piece 20 is calculated from the apparent volume and the actual volume ratio, and the moisture content of the wooden piece 20 is measured together with the measured mass of the wooden piece 20 and the known total dry density. Therefore, regardless of the shape of the wooden piece 20, the moisture content can be measured for wood pieces of various shapes and forms. Simple and quick moisture content measurement is realized without going through a drying process as in the total drying method.

[0051] The present invention is not limited to the above-mentioned embodiment, and any design change that does not deviate from the gist of the present invention, including various modifications and corrections that a person with ordinary knowledge in the field of the present invention can conceive, is of course included in the present invention. For example, the actual volume ratio of wood may be obtained from image data captured by electromagnetic waves other than visible light, such as infrared rays or X-rays, and the moisture content may be calculated by the above-mentioned method. In addition, in the above-mentioned embodiment, an example was shown in which the actual volume ratio of wood is obtained from a captured two-dimensional image, but the actual volume ratio may also be calculated directly from a three-dimensional image captured using, for example, X-rays. [Explanation of symbols]

[0052] 10: moisture content measuring device, 11: container, 12: mass measuring unit, 14: imaging unit, 16: calculation processing unit, 20: wood

Claims

1. A mass measuring unit that measures the mass of the wood contained in the container; An imaging unit that images the wood; a processing unit that calculates the volume of the wood based on the apparent volume of the wood placed in the container and the actual volume ratio of the wood calculated from image data captured by the imaging unit, and calculates the moisture content of the wood based on the volume, the mass, and dry density information corresponding to the species of the wood.

2. 2. The moisture content measuring device according to claim 1, wherein the calculation processing unit binarizes the image data based on a brightness threshold value, and extracts the area of ​​the wood from the image data to obtain the actual volume ratio.

3. 3. The moisture content measuring device according to claim 2, wherein the calculation processing unit determines the brightness threshold value based on the brightness of the image data.

4. 4. The moisture content measuring device according to claim 1, wherein the wood is an aggregate of wood chips formed into chips.

5. A mass measuring step of measuring the mass of the wood contained in the container; an imaging step of imaging the wood; a calculation step of calculating a volume of the wood based on the apparent volume of the wood contained in the container and an actual volume ratio of the wood obtained from image data captured by the imaging step, and calculating a moisture content of the wood based on the volume, the mass, and total dry density information corresponding to the resin of the wood.

Images