JP7555103B2 - Information processing device, information processing method, and program - Google Patents

Description

One aspect of the present invention relates to a technology for estimating the spatial distribution of soil moisture.

In Japan, where precipitation is high, improving the drainage of crop-producing fields or reducing spatial unevenness in soil moisture leads to increased yields and higher quality for many crops. For this reason, there is a demand for technology that can monitor the soil moisture content of large-scale fields in a short period of time. The use of aerial images taken with a thermal infrared camera is effective in meeting this societal need.

Non-Patent Document 1 discloses a method for estimating soil moisture content from the amount of change in soil temperature by referring to thermal infrared images taken at different times. Non-Patent Document 2 discloses a method for detecting underground culvert pipes from the distribution of soil temperature by referring to thermal infrared images, utilizing the difference in the change in ground surface temperature caused by the amount of soil moisture depending on whether or not there is an underground culvert pipe buried in the soil.

Anne Verhoef, Remote estimation of thermal inertia and soil heat flux for bare soil. Agricultural and Forest Meteorology, 123(2004), pp.221-236. Barry Allred, Neal Eash, Robert Freeland, Luis Martinez, and DeBonne Wishart. Effective and efficient agricultural drainage pipe mapping with UAS thermal infrared imagery: A case study. Agricultural Water Management, 197(2018), pp.132-137.

The above-mentioned technology estimates the spatial distribution of soil moisture by using a thermal infrared camera to measure the spatial distribution of ground surface temperature, which is caused by the amount of soil moisture. However, because soil surface temperature is affected by weather conditions and changes from moment to moment, the accuracy of moisture estimation varies depending on the timing of the image capture. However, there has been no method to date that can determine the optimal image capture time for moisture estimation, and there is a problem in that the spatial distribution of soil moisture cannot be obtained efficiently.

One aspect of the present invention has been made in consideration of the above problems, and aims to estimate the optimal time for capturing thermal infrared images to estimate the spatial distribution of soil moisture.

To solve the above problem, an information processing device according to one aspect of the present invention includes an acquisition unit that acquires location information indicating the location of soil for which the spatial distribution of soil moisture is to be estimated, date information indicating the date on which a thermal infrared image is captured to be referenced in the estimation of the spatial distribution, and soil quality information indicating the soil quality of the soil at the location, and an estimation unit that estimates the time on the date when the difference in ground surface temperature between wet and dry conditions of the soil at the location is maximum by referring to the location information, the date information, and the soil quality information.

According to one aspect of the present invention, it is possible to estimate the time suitable for capturing thermal infrared images to estimate the spatial distribution of soil moisture.

1 is a functional block diagram illustrating an example of the configuration of an information processing device according to an embodiment. FIG. 2 is a diagram showing an example of a thermal infrared image. FIG. 1 is a diagram showing an example of the relationship between ground surface temperature and volumetric water content. 1 is a flowchart showing a flow of processing by an information processing device. 2 shows an example of a screen for a user to input each piece of information.

[Embodiment]
An embodiment of the present invention will be described in detail below. In this embodiment, an information processing device that estimates a time suitable for capturing a thermal infrared image for estimating a spatial distribution of soil moisture will be described. The thermal infrared image of soil may be captured from the air by, for example, a drone or a UAV (Unmanned Aerial Vehicle).

1. Example of the configuration of an information processing device
1 is a functional block diagram showing an example of the configuration of an information processing device 1 according to the present embodiment. As shown in FIG. 1, the information processing device 1 includes a control unit 10, a storage unit 16, a display unit 20, and an input unit 18.

The control unit 10 is a control device such as a CPU that controls the entire information processing device 1, and also functions as an acquisition unit 12 and an estimation unit 14.

The acquisition unit 12 acquires location information indicating the location (range) of the soil for which the spatial distribution of soil moisture is to be estimated, date information indicating the date on which the thermal infrared image referenced in the estimation of the spatial distribution was captured, and soil quality information indicating the soil quality of the soil at the location.

Here, the location information may be information specified by, for example, latitude and longitude, or information specified by address. Also, the soil information may be information classified by, for example, the size of soil particles, or information classified by the saturated water content.

The estimation unit 14 refers to the location information, date information, and soil type information to estimate the time on the date when the difference in ground surface temperature between wet and dry conditions of the soil at the location indicated by the location information is maximum.

Here, the wet condition means the moisture content condition at the location that tends to be the wettest in a given range under certain weather conditions, which is a given range for estimating the spatial distribution of soil moisture. The dry condition means the moisture content condition at the location that tends to be the driest in the given range. The moisture content of the soil under the wet and dry conditions may be acquired by the acquisition unit 12 from a sensor (not shown) separately provided in the information processing device 1, or may be input by the user via the input unit 18, based on a measured value. The weather conditions mentioned above are, for example, conditions related to the amount of solar radiation, temperature, humidity, or weather. In the present disclosure, the moisture content of the soil may also mean the amount of moisture contained in the soil per unit volume, or the volumetric water content.

The memory unit 16 is a storage device that stores various information, for example, a table showing the correspondence between soil moisture and ground surface temperature under various weather conditions.

The display unit 20 is a display panel that displays text, moving images, etc., based on the control of the control unit 10. The input unit 18 is an interface such as a keyboard that allows the user to perform input operations on the information processing device 1.

The information processing device 1 may also be configured to access an external device, for example, via the Internet, and the control unit 10 may acquire information regarding weather conditions, which will be described later.

Figure 2 shows an example of a thermal infrared image. In Figure 2, the rectangular area 24 separated by the walkway 22 is the soil, and the brighter areas have a higher ground surface temperature. In the lower part of the image in Figure 2, a black weed control sheet has been placed over the walkway 22 and part of the rectangular area 26, which makes the ground surface temperature higher in that area. However, in the rectangular area 24 where the soil is exposed, the soil shown in the upper part of the image is measured to have a higher ground surface temperature than the soil shown in the lower part of the image. This is because the soil shown in the upper part of the image has less moisture.

3 shows the relationship between soil surface temperature and volumetric water content at a first time (10:00) and a second time (15:00) at the same location and date, respectively. In each graph, the horizontal axis corresponds to soil surface temperature, and the vertical axis corresponds to soil volumetric water content. In addition, " ^R2 " at the top of the graph indicates the decision variable used in the statistical calculation.

As shown in each graph, the soil surface temperature and volumetric moisture content change depending on the time of day, but the general trend is that the more moisture there is in the soil, the lower the soil surface temperature.

In addition, the ground surface temperature difference between wet conditions and dry conditions at the first time and the second time is different. In the case of the first time corresponding to the explanatory diagram 30, the ground surface temperature is about 30 degrees in wet conditions where the soil volumetric moisture content is about 30%, and the ground surface temperature is about 45 degrees in dry conditions where the soil volumetric moisture content is about 10%. That is, the ground surface temperature difference at the first time is about 15 degrees. On the other hand, in the case of the second time corresponding to the explanatory diagram 32, the ground surface temperature is about 25 degrees in wet conditions where the soil volumetric moisture content is about 25%, and the ground surface temperature is about 35 degrees in dry conditions where the soil volumetric moisture content is about 10%. That is, the ground surface temperature difference at the second time is about 10 degrees. Of the first time and the second time shown in FIG. 3, the first time, which has a larger ground surface temperature difference, is more suitable for capturing a thermal infrared image.

In addition, by using thermal infrared images taken at the time when the difference in ground surface temperature is greatest on a certain date, the differences in the spatial distribution of soil moisture are more emphasized, making it possible to estimate the spatial distribution of soil moisture with higher accuracy than if thermal infrared images taken at other times were used. In other words, the time when the difference in ground surface temperature is greatest is an extremely suitable time for taking thermal infrared images.

2. Processing example of information processing device
The flow of processing in the information processing device 1 according to this embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the flow of processing by the information processing device 1 according to this embodiment.

In step S101, the acquisition unit 12 acquires location information, date information, and soil quality information. FIG. 5 shows an example of a screen displayed on the display unit 20, which allows the user to input each piece of information via the input unit 18. In the example of FIG. 5, latitude and longitude values are used as location information. Also, "0616" in the screen indicates June 16th, which is an example of date information. Also, "soil type" corresponds to soil quality information, and one of "Roam," "Sand," and "FineSand," which are classified according to the size of the soil particles, is selected. In this example, "FineSand" has the largest soil particles, and "Roam" has the smallest soil particles. Note that the input screen and input format of each piece of information are not limited to those exemplified in FIG. 4. Also, each piece of information acquired by the acquisition unit 12 is not limited to that input to the information processing device 1 by the user's operation.

In step S102, the estimation unit 14 refers to the location information and date information acquired by the acquisition unit 12 and estimates the weather conditions on the date indicated by the date information. The estimation unit 14 estimates, for example, the amount of solar radiation per unit time as the weather conditions on the above date.

In step S103, the estimation unit 14 refers to the soil information and estimates the ground surface temperature of the soil of the soil type indicated by the soil conditions, which is the ground surface temperature under wet and dry conditions under each of the weather conditions on the above date, by calculating thermal parameters and calculating the energy balance at the ground surface.

In step S104, the estimation unit 14 estimates the difference in ground surface temperature between wet and dry soil conditions for each predetermined time on the date indicated by the date information. Here, the predetermined time is not limited to a specific time and may be, for example, one minute.

In step S105, the estimation unit 14 estimates the time when the difference in ground surface temperature between wet and dry soil conditions is maximum on the date indicated by the date information. Also, in this step S105, the control unit 10 causes the display unit 20 to display the above time, as shown in FIG. 5.

The above describes an information processing method realized by the information processing device 1, which includes an acquisition step of acquiring location information indicating the location of the soil for which the spatial distribution of soil moisture is to be estimated, date information indicating the date on which a thermal infrared image is captured to be referenced in the estimation of the spatial distribution, and soil quality information indicating the soil quality of the soil at the location, and an estimation step of estimating the time on the date when the difference in ground surface temperature between wet and dry conditions of the soil at the location is maximum, by referring to the location information, the date information, and the soil quality information.

The above configuration makes it possible to estimate the optimal time to capture thermal infrared images to estimate the spatial distribution of soil moisture.

[Software implementation example]
The control block of the information processing device (particularly the acquisition unit 12 and the estimation unit 14) may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software.

In the latter case, the information processing device includes a computer that executes the instructions of a program, which is software that realizes each function. The computer includes, for example, one or more processors, and a computer-readable recording medium that stores the program. The object of the present invention is achieved by the processor reading the program from the recording medium and executing it in the computer. The processor can be, for example, a CPU (Central Processing Unit). The recording medium can be a "non-transient tangible medium," such as a ROM (Read Only Memory), tape, disk, card, semiconductor memory, programmable logic circuit, etc. The computer may also include a RAM (Random Access Memory) that expands the program. The program may be supplied to the computer via any transmission medium (such as a communication network or broadcast waves) that can transmit the program. One aspect of the present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in different embodiments.

1 Information processing device 10 Control unit 12 Acquisition unit 14 Estimation unit 16 Storage unit 18 Input unit 20 Display unit

Claims (5)

an acquisition unit that acquires location information indicating a location of a soil for which a spatial distribution of soil moisture is to be estimated, date information indicating a date on which a thermal infrared image to be referenced in the estimation of the spatial distribution of the soil moisture was captured, and soil quality information indicating the soil quality of the soil at the location;
and an estimation unit that estimates the time on the date when the difference in ground surface temperature between wet and dry conditions of the soil at the location is maximum by referring to the location information, the date information, the soil type information, and information indicating the correspondence between values related to soil moisture and ground surface temperature at each time. The estimation unit is
estimating weather conditions on the date by referring to the location information and the date information;
estimating a ground surface temperature of soil of the soil type under wet conditions and dry conditions under the weather conditions by referring to the soil type information and information indicating the correspondence relationship under the weather conditions;
Estimating a ground surface temperature difference between wet and dry conditions of the soil for each predetermined time on the date;
2. The information processing apparatus according to claim 1, further comprising: a time on the date when the ground surface temperature difference is maximum; The information processing device according to claim 2, characterized in that the weather conditions include at least conditions related to the amount of solar radiation. 1. An information processing method performed by an apparatus, comprising:
an acquisition step in which the device acquires location information indicating a location of soil for which a spatial distribution of soil moisture is to be estimated, date information indicating a date on which a thermal infrared image to be referenced in the estimation of the spatial distribution is taken, and soil quality information indicating the soil quality of the soil at the location;
and an estimation step in which the device estimates the time on the date when the difference in ground surface temperature between wet and dry conditions of the soil at the location is maximum by referring to the location information, the date information, the soil type information, and information indicating the correspondence between values related to soil moisture at each time and ground surface temperature. A program for causing a computer to function as the information processing device according to claim 1, the program causing a computer to function as the acquisition unit and the estimation unit.

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