Mowing determination system and mowing determination method

Abstract

To provide a mowing determination system and a mowing determination method that can determine whether or not harvesting is appropriate based on optical images without using NDVI.SOLUTION: A mowing determination system of the present invention is a system that estimates the height of herbaceous plants using images, and is equipped with herbaceous plant pixel value calculation means, standard pixel value calculation means, exposure correction value calculation means, grass height calculation formula setting means, and mowing determination means. Of these, the exposure correction value calculation means is means for calculating "an exposure correction value" obtained by dividing the herbaceous plant pixel value by the standard pixel value. The mowing determination means determines that the grass height of the surveyed image is suitable for mowing work when the exposure correction value of the surveyed image falls below the exposure correction threshold value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a technology for estimating the height of herbs, and more specifically, to a mowing judgment system and a mowing judgment method that use an image obtained by photographing herbs and a standard reflector to determine whether or not mowing work is appropriate. [Background technology]

[0002] For example, when the temperature rises from winter to spring, warm-climate grasses such as Zoysiagrass begin to synthesize chlorophyll in their chloroplasts, and as they begin photosynthesis and other vital activities, their grass height grows. However, if the grass is left in a long state, it will fall over, which can result in humidity and lack of sunlight between the grass, which can lead to disease and withering.

[0003] In order to prevent the lawn from falling over, it is necessary to maintain an appropriate grass height, and therefore the grass is mowed at appropriate times. When determining the time to mow, the grass should be mowed after checking the site, but it is known from experience that the grass is most likely to grow taller (May, July, and November), and therefore mowing is carried out at the designated time without checking the site.

[0004] However, in recent years, it is said that the global temperature is rising due to an increase in greenhouse gases, and the number of extremely hot days has increased compared to before, and the period when the temperatures are high has also changed. As a result, the period when the grass is likely to grow taller has also changed, and if mowing work is carried out at the empirically known period as described above, the grass has already grown excessively, and it is not uncommon for it to even fall over.

[0005] In light of this, the need to manage the grass height of lawns is being recognized anew. One way to manage grass height is for the manager to visit the site and visually check the grass height, but this visual management is unexpectedly difficult. For example, depending on the timing of the visit, it may already be too late to mow the grass, and it would be a considerable effort and cost to go to the site repeatedly, even if it means wasting time, in order not to miss the time to mow. In the first place, since it is based on human judgment, depending on the experience and insight, it is possible that the judgment will not be appropriate, and it is not realistic to secure a knowledgeable technician each time.

[0006] Therefore, there has been a demand for technology that can objectively grasp the condition of a lawn without relying on human judgment. For example, Patent Document 1 proposes a work vehicle that can measure the activity of the lawn, calculate the Normalized Difference Vegetation Index (NDVI), and perform lawn maintenance based on the NDVI. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2019-88252 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, there are several problems with the technology of understanding the condition of grass using NDVI, including that of Patent Document 1. First, in order to calculate NDVI, it is necessary to acquire special images, and to acquire these images, a special camera that can detect multiple wavelength bands, such as a spectral camera, must be prepared. In other words, there is a problem that it is quite costly to understand the grass height.

[0009] Another problem is that no significant relationship is observed between plant height and NDVI. Figure 9 shows the results of a verification performed by the inventor of the present application on Zoysia japonica, and is a scatter plot with plant height on the horizontal axis and NDVI on the vertical axis. As shown in this figure, no specific relationship was observed between plant height and NDVI. For example, when mowing work is performed when the plant height exceeds 40 cm, there are two possible NDVI thresholds, 0.23 and 0.50, but it is not possible to determine which one should be adopted. The reason why there is no significant causal relationship between plant height and NDVI is that the physical growth amount (plant height) of Zoysia japonica is not easily affected by the chemical growth amount (the plant vitality indicated by NDVI). In other words, it is considered that this is due to the difference between the timing when Zoysia japonica slows down its growth rate toward winter and the timing when it reduces its activity.

[0010] Furthermore, the wavelength band used to calculate NDVI includes near-infrared light, which is easily affected by heat, so there is also the problem that conditions such as time of day and weather must be constant when acquiring images.

[0011] The object of the present invention is to solve the problems associated with the conventional technology, i.e., to provide a mowing judgment system and a mowing judgment method that can determine the appropriateness of mowing work based on optical images without using NDVI. [Means for solving the problem]

[0012] The present invention was made by focusing on the fact that it utilizes a survey image containing herbs and a standard reflector, calculates a correction value based on the pixel values ​​related to the herbs and the pixel values ​​related to the standard reflector, and judges whether or not mowing work is appropriate based on that correction value, and is an invention based on an unprecedented idea.

[0013] The mowing judgment system of the present invention is a system for estimating the height of herbaceous plants using an image, and is equipped with a herbaceous plant pixel value calculation means, a standard pixel value calculation means, an exposure correction value calculation means, a grass height calculation formula setting means, and a mowing judgment means. Among these, the herbaceous plant pixel value calculation means is a means for calculating a "herbaceous plant pixel value" based on a pixel value related to a pixel of the herbaceous plant in an "inspection image (an image including herbaceous plants and a standard reflector)", the standard pixel value calculation means is a means for calculating a "standard pixel value" based on a pixel value related to a pixel of the standard reflector in the inspection image, and the exposure correction value calculation means is a means for calculating an "exposure correction value" obtained by dividing the herbaceous plant pixel value by the standard pixel value. The grass height calculation formula setting means is a means for setting a grass height calculation formula (a formula for the relationship between the grass height actual value and the exposure correction actual value), and the mowing judgment means is a means for judging the suitability of the mowing operation by checking the exposure correction value against an exposure correction threshold value. The exposure correction threshold value is calculated based on a previously set planned grass height and a grass height calculation formula. The mowing determination means determines that the grass height in the survey image is suitable for mowing work when the exposure correction value in the survey image falls below the exposure correction threshold.

[0014] The mowing determination system of the present invention may further include a grass height calculation means for calculating a "grass height estimate" based on a "grass height calculation formula (a formula for the relationship between the grass height and the exposure correction value)" and the exposure correction value related to the survey image.

[0015] The mowing determination system of the present invention may use RGB values ​​as pixel values. In this case, the herbaceous pixel value calculation means calculates a herbaceous pixel value based on an R value, a herbaceous pixel value based on a G value, and a herbaceous pixel value based on a B value, and the standard pixel value calculation means calculates a standard pixel value based on an R value, a standard pixel value based on a G value, and a standard pixel value based on a B value. The exposure correction value calculation means calculates an exposure correction value related to the R value based on the herbaceous pixel value based on the R value and the standard pixel value based on the R value, calculates an exposure correction value related to the G value based on the herbaceous pixel value based on the G value and the standard pixel value based on the G value, and calculates an exposure correction value related to the B value based on the herbaceous pixel value based on the B value and the standard pixel value based on the B value.

[0016] The mowing determination system of the present invention may use grayscale values ​​as pixel values. In this case, the herbaceous pixel value calculation means calculates the herbaceous pixel value based on the grayscale value, the standard pixel value calculation means calculates the standard pixel value based on the grayscale value, and the exposure compensation value calculation means calculates the exposure compensation value related to the grayscale value.

[0017] The mowing judgment method of the present invention is a method for estimating the height of herbaceous plants using an image, and includes a reflector arrangement step, an image acquisition step, a herbaceous plant pixel value calculation step, a standard pixel value calculation step, an exposure correction value calculation step, a grass height calculation formula setting step, and a mowing judgment step. In the reflector arrangement step, a standard reflector is arranged at a height substantially the same as (including the same as) the grass height, and in the image acquisition step, a survey image is acquired so that the herbaceous plant and the standard reflector are included. In the herbaceous plant pixel value calculation step, a herbaceous plant pixel value is calculated, in the standard pixel value calculation step, a standard pixel value is calculated, and in the exposure correction value calculation step, an exposure correction value is calculated. In the grass height calculation formula setting step, a grass height calculation formula is set, and in the mowing judgment step, the exposure correction value is compared with an exposure correction threshold value to judge whether mowing is appropriate. In the mowing judgment step, when the exposure correction value for the survey image is below the exposure correction threshold value, it is judged that the grass height for the survey image is appropriate for mowing.

[0018] The mowing determination method of the present invention may also be a method in which a standard reflector is placed on the herbaceous plant in the reflector arrangement step.

[0019] The method for determining whether the crop is to be harvested may be a method for placing a standard reflector with a mark having coordinates in the reflector placement step. In this case, the planar position of the survey image can be identified based on the standard reflector included in the survey image. Effect of the Invention

[0020] The mowing determination system and the mowing determination method of the present invention have the following advantages. (1) The only on-site work required is to collect images, which reduces the workload of determining grass height. (2) The appropriateness of mowing can be judged based on the calculated estimated grass height, which means that an objective judgment can be made without relying on human judgment, and the judgment can be made easily and quickly. (3) Since the grass height calculation formula is set in advance, the planned grass height that serves as the basis for mowing work can be set appropriately, meaning that mowing work can be carried out based on flexible judgment. [Brief description of the drawings]

[0021] [Figure 1] 1 is a block diagram showing the main configuration of a mowing determination system 100 according to the present invention. [Diagram 2] FIG. 2 is a side view showing a standard reflector placed on grass. [Diagram 3] A model diagram showing the relationship between the herbaceous pixel values ​​calculated using the R, G, and B values, the standard pixel values, the exposure compensation value, and the grass height calculation formula. [Figure 4] FIG. 13 is a graph showing a grass height calculation formula that shows the relationship between the "grass height actual value" and the "exposure correction actual value related to the R value". [Diagram 5] FIG. 13 is a graph showing a grass height calculation formula that indicates the relationship between the "grass height actual value" and the "exposure correction actual value related to the G value." [Figure 6] FIG. 13 is a graph showing a grass height calculation formula that shows the relationship between the "grass height actual value" and the "exposure correction actual value related to B value". [Figure 7] 2 is a flow chart showing an example of the main process flow of the mowing determination system 100 of the present invention. [Figure 8] 1 is a flow chart showing the flow of main steps of the mowing determination method of the present invention. [Figure 9] 1 is a scatter plot showing the results of a verification carried out by the inventor of the present application on Zoysia grass. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] An embodiment of the mowing judgment system and mowing judgment method of the present invention will be described with reference to the drawings. The present invention is for judging the suitability of mowing work on herbaceous plants, and can be applied to various herbaceous plants. For example, the present invention can be applied to ground cover plants among herbaceous plants, and among ground cover plants, warm-season turfgrass and cool-season turfgrass of the Poaceae family in particular. For convenience, the present invention will be described with an example of a turfgrass such as Zoysia grass (warm-season turfgrass and cool-season turfgrass) as the herbaceous plant.

[0023] 1. Mowing Judgment System First, the mowing judgment system of the present invention will be described in detail. The mowing judgment system of the present invention can be used to judge the suitability of mowing work using the mowing judgment method of the present invention. Therefore, the mowing judgment system of the present invention will be described first, and then the mowing judgment method of the present invention will be described.

[0024] 1 is a block diagram showing the main components of a reaping determination system 100 of the present invention. As shown in this figure, the reaping determination system 100 of the present invention is configured to include a herbaceous plant pixel value calculation means 101, a standard pixel value calculation means 102, an exposure correction value calculation means 103, a grass height calculation formula setting means 104, and a reaping determination means 105, and can also be configured to include a grass height calculation means 106, an investigation image storage means 107, an achievement data storage means 108, a grass height calculation formula storage means 109, etc.

[0025] Among the main elements constituting the mowing judgment system 100, the herbaceous plant pixel value calculation means 101, the standard pixel value calculation means 102, the exposure correction value calculation means 103, the grass height calculation formula setting means 104, the mowing judgment means 105, and the grass height calculation means 106 can be manufactured as dedicated devices, or a general-purpose computer device can be used. That is, the computer device executes arithmetic processing according to a predetermined program, thereby performing processing specific to each means. This computer device is equipped with a processor such as a CPU, and memories such as ROM and RAM, and some further include input means such as a mouse and a keyboard, and a display, and can be configured, for example, by a personal computer (PC), a server, a tablet PC such as an iPad (registered trademark), a smartphone, etc.

[0026] In addition, the survey image storage means 107, the performance data storage means 108, and the grass height calculation formula storage means 109 can use a storage device of a general-purpose computer, or can be constructed in a database server. When constructed in a database server, they can be placed in a local network (LAN: Local Area Network) or can be a cloud server that stores data via the Internet.

[0027] Below, each of the main elements constituting the mowing determination system 100 will be described in detail.

[0028] (Survey image storage means) The survey image storage means 107 is a means for storing a "survey image" acquired at a site where grass is growing. The survey image is an image obtained by photographing the grass at the site together with a standard reflector, in other words, an image including herbaceous plants and the standard reflector in the angle of view. This standard reflector can be any of various types that have been used in the past, for example, a gray standard reflector with a reflectance of 18% can be used.

[0029] When acquiring survey images, it is advisable to place a standard reflector at the same height as the grass so that survey images acquired at different times can be evaluated equally. For example, as shown in Figure 2, it is advisable to place the standard reflector RF on the grass GR, or to install the standard reflector RF on a surrounding structure (e.g., a promenade) at the same height as the grass GR relative to the sun, or to use a tripod or the like to install the standard reflector RF.

[0030] It is also desirable for the survey image to be an image close to an orthographic projection. For this reason, it is advisable to take the image using a fixed camera placed at a high position, or to take an aerial photograph using a camera mounted on an aircraft such as a drone. The camera for taking the survey image can be any of various conventional photographing means, including digital cameras and digital video cameras. When an image close to an orthographic projection can be obtained, it can be used as a survey image as it is, or it can be used as a survey image after performing so-called ortho-correction on the obtained image.

[0031] When grass grows over a wide area, a sample image taken partially can be used as the survey image, or of course the entire area can be photographed and all the images obtained can be used as the survey image. In either case, it is a good idea to add coordinates to the survey image so that it is clear which area of ​​the site the survey image was taken of. Specifically, in the case of a fixed camera, the installation position and the field of view range should be known in advance, and in the case of aerial photography using an aircraft, the camera position at the time of shooting should be determined using the Global Navigation Satellite System (GNSS). Alternatively, it is possible to place signs with known position coordinates at key points on the site before taking a photograph, and to determine the position of the survey image based on the signs included in the field of view. In this case, a standard reflector RF with a sign (e.g., a cross) can be used.

[0032] (Herbage pixel value calculation means) The herbaceous pixel value calculation means 101 is a means for calculating a "herbaceous pixel value" based on a survey image. The procedure for calculating herbaceous pixel values ​​by the herbaceous pixel value calculation means 101 will be described below. First, pixels of the portion in which the grass GR is photographed are extracted from the survey image (hereinafter simply referred to as "herbaceous pixels"). At this time, the herbaceous pixels can be extracted automatically using various conventionally used image processing techniques, or the herbaceous pixels can be extracted manually, so to speak, by an operator visually inspecting the image.

[0033] Usually, multiple herbaceous pixels are extracted from the survey image, and the pixel values ​​related to these herbaceous pixel values ​​are statistically processed to calculate a representative herbaceous pixel value. Here, the pixel value is a value set based on a color model for computer processing. There are various color models, such as the RGB model with three basic colors of red, green, and blue, the HSV model with hue H, saturation S, and value of brightness V, the CMYK model with four basic colors of cyan, magenta, yellow, and black (key color), as well as the NCS model, the Ostwald color system, and the grayscale model that represents shades of light and dark.

[0034] In statistical processing of pixel values, various conventional statistical methods can be used, such as a method for calculating a simple average value, a method for calculating a weighted average value with weighting, a method for calculating a mode value, a method for calculating a median value, etc. When a grayscale (e.g., 0 to 255) is used as the color model, one type of herbaceous pixel value is calculated, but when an RGB model is used, it is preferable to calculate three types of herbaceous pixel values ​​using R values, G values, and B values ​​as shown in Figure 3.

[0035] (Standard pixel value calculation means) The standard pixel value calculation means 102 is a means for calculating a "standard pixel value" based on the survey image. The procedure for calculating the standard pixel value by the standard pixel value calculation means 102 will be described below. First, pixels (hereinafter simply referred to as "standard pixels") in the portion where the standard reflector RF is photographed are extracted from the survey image. At this time, the standard pixels can be extracted automatically using various conventionally used image processing techniques, or the standard pixels can be extracted manually by an operator while visually checking the image.

[0036] Usually, multiple standard pixels are extracted from a survey image, and the pixel values ​​of these standard pixels are statistically processed to calculate a standard pixel value that is a representative value. As with herbaceous pixel values, this pixel value can be set based on the RGB model, the laser scale, the HSV model, the CMYK model, the NCS model, the Ostwald color system, or other models. As with herbaceous pixel values, various statistical methods can be used to calculate simple averages, weighted averages, modes, medians, and other values. When grayscale is used as the color model, one type of standard pixel is calculated, and when the RGB model is used, three types of standard pixel values ​​based on the R, G, and B values ​​are calculated as shown in Figure 3.

[0037] (Exposure compensation value calculation means) The exposure compensation value calculation means 103 is a means for calculating a value obtained by dividing the herbaceous pixel value by the standard pixel value (hereinafter referred to as "exposure compensation value"). Therefore, when a grayscale is adopted as the color model, one type of exposure compensation value is calculated, and when an RGB model is adopted, three types of exposure compensation values ​​based on the R value, G value, and B value are calculated as shown in FIG.

[0038] (Method of setting the grass height calculation formula) The grass height calculation formula setting means 104 is a means for setting the "grass height calculation formula." The procedure by which the grass height calculation formula setting means 104 sets the grass height calculation formula will be described below. First, the actually measured grass height of the lawn GR (hereinafter referred to as the "grass height actual value") and an exposure correction value calculated based on a survey image including the lawn GR and the standard reflector RF (particularly referred to as the "exposure correction actual value") are acquired. The grass height actual value and exposure correction actual value acquired here (hereinafter collectively referred to as the "actual data") are stored in the actual data storage means 108 (FIG. 1).

[0039] When multiple pieces of performance data are obtained, these pieces of performance data are scattered in a coordinate system with the horizontal axis representing the actual grass height value and the vertical axis representing the exposure correction actual value. Then, a regression analysis is performed on the multiple scattered performance data to set a grass height calculation formula with the actual grass height value as an explanatory variable and the exposure correction actual value as a target variable. When a grayscale is used as the color model, one type of grass height calculation formula is set, and when an RGB model is used, three types of grass height calculation formulas based on R, G, and B values ​​as shown in FIG. 3 are set. FIG. 4 is a graph showing the grass height calculation formula that represents the relationship between the "actual grass height value" and the "exposure correction actual value related to the R value", FIG. 5 is a graph showing the grass height calculation formula that represents the relationship between the "actual grass height value" and the "exposure correction actual value related to the G value", and FIG. 6 is a graph showing the grass height calculation formula that represents the relationship between the "actual grass height value" and the "exposure correction actual value related to the B value". The grass height calculation formula set by the grass height calculation formula setting means 104 is stored in the grass height calculation formula storage means 109 (FIG. 1).

[0040] (Method of calculating grass height) The grass height calculation means 106 is a means for calculating an estimate of the grass height of the lawn GR on-site (hereinafter referred to as the "estimated grass height value"). Specifically, the grass height estimate value is calculated by inputting an exposure correction value into the grass height calculation formula set by the grass height calculation formula setting means 104. For example, when the exposure correction value related to the G value is calculated as 0.3 from the acquired survey image, the grass height estimate value is calculated as 120 mm according to the grass height calculation formula based on the G value shown in FIG. 5. Similarly, the grass height estimate value based on the R value can be calculated by inputting an exposure correction value related to the R value into the grass height calculation formula based on the R value, and the grass height estimate value based on the B value can be calculated by inputting an exposure correction value related to the B value into the grass height calculation formula based on the B value. When different grass height estimate values ​​are obtained in this way, it is preferable to set the value according to the grass height calculation formula with the highest correlation coefficient (the grass height calculation formula based on the G value in the case of FIGS. 4 to 6) as the estimated grass height value.

[0041] (Reaping judgment means) The mowing determination means 105 is a means for determining whether mowing work is appropriate for the grass GR at the site. Specifically, the exposure correction value obtained from the survey image is compared with a predetermined threshold value (hereinafter referred to as the "exposure correction threshold value"), and when this exposure correction value is below the exposure correction threshold value, it is determined that the grass height of the grass GR is appropriate for mowing work. This exposure correction threshold value is obtained by setting the grass height at which mowing work should be performed (hereinafter referred to as the "planned grass height") in advance and then inputting this planned grass height into the grass height calculation formula. For example, when the planned grass height is set to 40 mm, the exposure correction threshold value is obtained as 0.509 according to the grass height calculation formula based on the R value shown in FIG. 4, the exposure correction threshold value is obtained as 0.529 according to the grass height calculation formula based on the G value shown in FIG. 5, and the exposure correction threshold value is obtained as 0.227 according to the grass height calculation formula based on the B value shown in FIG. 6. When different exposure compensation thresholds are required in this way, it is possible to determine that mowing is suitable when the exposure compensation values ​​for all of the R, G, and B values ​​are below the exposure compensation thresholds, or to determine that mowing is suitable when the exposure compensation value for any of the R, G, and B values ​​is below the exposure compensation thresholds. Also, it is possible to determine the suitability of mowing by prioritizing the evaluation using the grass height calculation formula with the highest correlation coefficient (the grass height calculation formula based on the G value in the case of Figures 4 to 6).

[0042] The mowing determination means 105 can compare the estimated grass height calculated by the grass height calculation means 106 with the planned grass height, and when this estimated grass height value exceeds the planned grass height, determine that the grass height of the lawn GR is suitable for mowing work. In this case, too, it can be specified to determine that the grass height is suitable for mowing work when the estimated grass height value exceeds the planned grass height in all of the R value, G value, and B value, or to determine that the grass height is suitable for mowing work when the estimated grass height value exceeds the planned grass height in any of the R value, G value, and B value.

[0043] (Processing flow) Below, the main processing of the reaping determination system 100 will be described in detail with reference to Fig. 7. Fig. 7 is a flow diagram showing an example of the flow of main processing of the reaping determination system 100 of the present invention, in which the central column shows the processing to be executed, the left column shows information required for that processing, and the right column shows information resulting from that processing.

[0044] First, the grass height calculation formula is set by the grass height calculation formula setting means 104. Specifically, the "grass height actual value" of the lawn GR is measured, and an inspection image including the lawn GR and the standard reflector RF is acquired, and an exposure correction value (i.e., exposure correction actual value) is calculated, and a regression analysis is performed on multiple actual data scattered in the coordinate system (grass height actual value-exposure correction actual value) to set the grass height calculation formula (Step 201 in FIG. 7). Next, a planned grass height is set, and the exposure correction threshold value is obtained by inputting this planned grass height into the grass height calculation formula (Step 202 in FIG. 7).

[0045] Once the grass height calculation formula is set and the exposure correction threshold is calculated, a survey image is acquired in the vegetation area of ​​the grass GR that is the actual target of judgment, so that the grass GR and the standard reflector RF are included. Then, based on this survey image, the grass pixel value calculation means 101 calculates the grass pixel value (Step 203 in FIG. 7), and the standard pixel value calculation means 102 calculates the standard pixel value (Step 204 in FIG. 7).

[0046] When the herbaceous pixel value and the standard pixel value are obtained, the exposure correction value calculation means 103 calculates the exposure correction value (Step 205 in FIG. 7), and when the exposure correction value falls below the exposure correction threshold value, the mowing determination means 105 determines that the grass height of the lawn GR is suitable for mowing work (Step 207 in FIG. 7). Alternatively, when the grass height estimated value calculated by the grass height calculation means 106 (Step 206 in FIG. 7) exceeds the planned grass height, it can also be determined that the grass height of the lawn GR is suitable for mowing work (Step 207 in FIG. 7).

[0047] 2.Reaping judgment method Next, the reaping judgment method of the present invention will be described. When judging the suitability of reaping work using the reaping judgment method of the present invention, the reaping judgment system 100 of the present invention described so far can be used. Therefore, we will avoid overlapping explanations with those of the reaping judgment system 100, and only explain the contents unique to the reaping judgment method of the present invention. In other words, the contents not described here are the same as those explained in "1. Reaping judgment system".

[0048] Fig. 8 is a flow chart showing the flow of the main steps of the reaping judgment method of the present invention. When judging the suitability of reaping work using the reaping judgment method of the present invention, first, a grass height calculation formula is set based on the performance data (grass height performance value and exposure correction performance value) (Step 301 in Fig. 8), and the exposure correction threshold is obtained by inputting the planned grass height into the grass height calculation formula (Step 302 in Fig. 8).

[0049] Once the grass height calculation formula is set and the exposure correction threshold is calculated, the process goes to the vegetation area of ​​the grass GR that is the actual subject of the judgment, and the standard reflector RF is placed (Step 303 in Fig. 8). At this time, it is advisable to place the standard reflector RF at a height equivalent to that of the grass GR, for example, by placing the standard reflector RF on the grass GR, setting the standard reflector RF on a surrounding structure at the same height as the grass GR, or setting the standard reflector RF using a tripod or the like.

[0050] Once the standard reflector RF is placed, a fixed camera or a camera mounted on a drone is used to obtain a survey image that includes the grass GR and the standard reflector RF in the field of view (Step 304 in Fig. 8). At this time, it is advisable to add coordinates to the survey image so that it is clear which area of ​​the site the survey image was taken of. For example, it is possible to place signs (with known position coordinates) at key locations on the site before taking an image, and to determine the position of the survey image based on the signs included in the field of view. In this case, a standard reflector RF with a sign (for example, a cross) attached to it can be used.

[0051] When the survey image is obtained, a herbaceous pixel value is calculated based on pixel values ​​relating to herbaceous pixels in the survey image (Step 305 in FIG. 8), a standard pixel value is calculated based on pixel values ​​relating to standard pixels (Step 306 in FIG. 8), and an exposure correction value is calculated based on the herbaceous pixel value and the standard pixel value (Step 307 in FIG. 8). Then, when the exposure correction value falls below the exposure correction threshold, it is determined that the grass height of the lawn GR is suitable for mowing work (Step 308 in FIG. 8). [Industrial Applicability]

[0052] The mowing determination system and mowing determination method of the present invention can be used to determine the height of various herbaceous plants, such as ground cover plants including warm-season turfgrass (e.g., Zoysia grass) and cool-season turfgrass. The present invention can prevent herbaceous plants from becoming diseased or dying, which means that vegetation can be properly maintained, and as a result, carbon dioxide absorption is promoted. Considering this, it can suppress the increase in greenhouse gases, which is an urgent issue at present, and is an invention that can be expected to not only be used industrially, but also to make a great contribution to society. [Explanation of symbols]

[0053] 100 The harvesting judgment system of the present invention 101 (of the cutting judgment system) herbaceous pixel value calculation means 102 (of the mowing judgment system) standard pixel value calculation means 103 (of the mowing judgment system) exposure correction value calculation means 104 (for the cutting judgment system) Grass height calculation formula setting means 105 (of the harvesting judgment system) harvesting judgment means 106 (for the cutting judgment system) grass height calculation means 107 (Mowing Judgment System) Survey Image Storage Means 108 (Mowing determination system) performance data storage means 109 (for the cutting judgment system) grass height calculation formula storage means GR Lawn RF standard reflector

Claims

1. A system for estimating the height of herbaceous plants using an image, comprising: a herbaceous plant pixel value calculation means for calculating a herbaceous plant pixel value based on a pixel value of the herbaceous plant in a survey image including the herbaceous plant and a standard reflector; a standard pixel value calculation means for calculating a standard pixel value based on pixel values ​​of the pixels of the standard reflector in the survey image; an exposure compensation value calculation means for calculating an exposure compensation value obtained by dividing the herbaceous pixel value by the standard pixel value; A grass height calculation formula setting means for setting a grass height calculation formula that represents a relationship between a grass height actual value and an exposure correction actual value; a mowing determination means for determining whether or not mowing work is appropriate by comparing the exposure correction value with an exposure correction threshold value, The exposure correction threshold is calculated based on the planned grass height and the grass height calculation formula, the mowing determination means determines that the grass height in the survey image is suitable for mowing work when the exposure correction value in the survey image is below the exposure correction threshold value; A mowing determination system comprising:

2. The method further includes a grass height calculation means for calculating a grass height estimation value based on the grass height calculation formula and the exposure correction value related to the survey image.

2. The mowing determination system according to claim 1 .

3. the herbaceous plant pixel value calculation means calculates, among RGB values ​​as pixel values, the herbaceous plant pixel value based on an R value, the herbaceous plant pixel value based on a G value, and the herbaceous plant pixel value based on a B value; the standard pixel value calculation means calculates the standard pixel value based on an R value, the standard pixel value based on a G value, and the standard pixel value based on a B value out of RGB values ​​as pixel values; the exposure compensation value calculation means calculates the exposure compensation value related to the R value based on the herbaceous pixel value based on the R value and the standard pixel value based on the R value, calculates the exposure compensation value related to the G value based on the herbaceous pixel value based on the G value and the standard pixel value based on the G value, and calculates the exposure compensation value related to the B value based on the herbaceous pixel value based on the B value and the standard pixel value based on the B value; 2. The mowing determination system according to claim 1 .

4. the herbaceous plant pixel value calculation means calculates the herbaceous plant pixel value based on a grayscale value as a pixel value; the standard pixel value calculation means calculates the standard pixel value based on a grayscale value as a pixel value; the exposure compensation value calculation means calculates the exposure compensation value based on the herbaceous pixel value based on a grayscale value and the standard pixel value based on a grayscale value; 2. The mowing determination system according to claim 1 .

5. A method for estimating the height of a herb using an image, comprising: A reflector arrangement step of arranging a standard reflector at a height equal to or substantially equal to the grass height; an image acquisition step of acquiring a survey image so as to include the herbaceous plant and the standard reflector; a herbaceous pixel value calculation step of calculating a herbaceous pixel value based on pixel values ​​of the herbaceous pixels in the survey image; a standard pixel value calculation step of calculating a standard pixel value based on pixel values ​​of the pixels of the standard reflector in the survey image; an exposure correction value calculation step of calculating an exposure correction value obtained by dividing the herbaceous pixel value by the standard pixel value; A grass height calculation formula setting step of setting a grass height calculation formula that represents a relationship between a grass height actual value and an exposure correction actual value; and a mowing determination step of determining whether or not mowing work is appropriate by comparing the exposure correction value with an exposure correction threshold value, The exposure correction threshold is calculated based on the planned grass height and the grass height calculation formula, In the mowing determination step, when the exposure correction value related to the survey image is below the exposure correction threshold, it is determined that the grass height related to the survey image is suitable for mowing work. A mowing determination method comprising:

6. In the reflector placement step, the standard reflector is placed on the herb.

6. The mowing determination method according to claim 5,

7. The standard reflector is provided with a mark having coordinates; A planar position of the survey image can be identified based on the standard reflector included in the survey image.

6. The mowing determination method according to claim 5,

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