Tree measuring apparatus and tree measuring system

Abstract

To provide a tree measuring apparatus capable of accurately determining whether a tree is in a growth state or a withered state by measuring temperature changes by a far-infrared image for changes of an outside temperature.SOLUTION: A tree measuring apparatus comprises: an image acquisition part 41 which acquires a first far-infrared image IN1 of a tree F imaged at first timing and a second far-infrared image IN2 of the tree imaged at second timing; and a growth determination part 42 which, regarding a tree F having a predetermined value or more of a difference between the acquired first far-infrared image IN1 and the acquired second far-infrared image IN2, determines a growth state of the tree F is in a withered state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tree measuring device that measures the growth state of a tree using an image. [Background technology]

[0002] As a technique for measuring plants, trees, etc. using images, for example, the techniques shown in Patent Documents 1 to 3 are disclosed.

[0003] The technology shown in Patent Document 1 is an automatic forest damaged tree detection device that accepts input of aerial image data and information specifying the detection range for damaged trees contained in the aerial image, generates a grid within the specified range and cuts out multiple rectangular images from the aerial image, and detects damaged trees contained in the rectangular images.In detecting damaged trees, it is determined whether the rectangular image contains a damaged tree, and the location information of the damaged tree is calculated.Supervised learning of an object detection model is performed using training data, and the learned object detection model is used to determine whether the rectangular image contains a damaged tree.The training data includes aerial images for training data that contain damaged trees and labeling applied to rectangles circumscribing the damaged trees.If it is determined that the cut-out rectangular image contains a damaged tree, the object detection model outputs a rectangle circumscribing the damaged tree, and the location information of the detected damaged tree is calculated based on that rectangle.

[0004] The technology disclosed in Patent Document 2 is a non-destructive metabolic product measuring device (measuring device) that irradiates light of at least two wavelengths, one of which has absorption sensitivity to the substance being measured and the other of which has no absorption sensitivity to metabolic products, onto the petiole or stalk of a growing plant to detect fluctuations in absorbance and measure changes in the movement of metabolic products passing through the petiole or stalk, corrects the measurement data using values ​​measured with light of a wavelength that has absorption properties for water but not for metabolic products, and measured values ​​that have absorption properties for both water and metabolic products, fixes the petiole or stalk of a growing plant to this measuring device, and feedback-controls the plant's cultivation environment factors based on the measurement data of metabolic products passing through the petiole or stalk.

[0005] The technology disclosed in Patent Document 3 involves photographing the surface of the object to be analyzed via satellite, generating a panchromatic image including trees, automatically extracting trees from the generated panchromatic image based on image features, surrounding the trees with a circle, calculating a co-occurrence matrix of the area inside the extracted circle, obtaining multispectral normalized data at the center of the circle, performing normalization processing, matching the training data with the extracted trees, creating a tree species estimation model using a multivariate analysis model, and using the analysis model to estimate the tree species of the trees extracted from the panchromatic image of the object to be analyzed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2023-105672 [Patent Document 2] Japanese Patent Publication No. 2020-95034 [Patent Document 3] Japanese Patent Application Publication No. 2019-144507 Summary of the Invention [Problem to be solved by the invention]

[0007] Patent Document 1 describes a method for automatically detecting damaged trees in a forest area under investigation from aerial image data of the forest area under investigation, but in the case of deciduous trees, for example, they lose their leaves in autumn and winter, making it difficult to identify the trees using visible light. In other words, there is a problem in that the period during which highly accurate investigations can be performed is limited.

[0008] The technology disclosed in Patent Document 2 detects fluctuations in absorptivity by irradiating the petiole or pedicel of a growing plant with light of two wavelengths, one with absorption sensitivity to the substance to be measured and the other with light insensitive to metabolic products. However, this technology is not capable of measuring the growth state of trees. Furthermore, because the growth environment of plants and trees (temperature, humidity, weather, etc.) changes in real time, the light absorption characteristics also change, making it difficult to obtain accurate measurement data in a steady state.

[0009] The technology disclosed in Patent Document 3 estimates the tree species by analyzing satellite images, but is not capable of determining the growth state (growing state / dead state) of the tree.

[0010] The present invention has been made to solve the above-mentioned problems, and aims to provide a tree measuring device that can accurately determine whether a tree is in a growing state or a dead state by measuring temperature changes in far-infrared images in response to changes in outside air temperature. [Means for solving the problem]

[0011] The tree measuring device of the present invention comprises an image acquisition means for acquiring at least a first far-infrared image of a tree captured at a first timing and a second far-infrared image of the tree captured at a second timing, and a growth determination means for determining that the growth state of a tree is dead for a tree for which the difference between the acquired first far-infrared image and the acquired second far-infrared image is greater than a predetermined value.

[0012] In this way, the tree measuring device of the present invention acquires far-infrared images of the tree to be measured taken at different times, and determines that the growth state of the tree for which the difference between the far-infrared images is greater than a predetermined value is dead.Therefore, if there is a large change in the far-infrared image representing the change in temperature in relation to environmental changes around the tree to be measured, it can be assumed that the tree is not metabolizing or is in a very poor metabolic state, thereby achieving the effect of being able to determine whether the tree to be measured is in a growing state or in a dead state. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing the system configuration of a tree measurement system according to a first embodiment. [Figure 2] 1 is a schematic diagram showing the hardware configuration of a tree measurement device according to a first embodiment. [Figure 3] 3 is a functional block diagram showing the configuration of a control unit in the tree measuring device according to the first embodiment. FIG. [Figure 4] 3A and 3B are diagrams showing an example of a far-infrared image and a differential image of a tree in a growing state in the tree measuring device according to the first embodiment. [Figure 5] 3A and 3B are diagrams showing an example of a far-infrared image and a differential image of a tree in a dead state in the tree measuring device according to the first embodiment. [Figure 6] FIG. 2 is a diagram showing an example of an image when a dead tree is identified in the tree measuring device according to the first embodiment. [Figure 7] 4 is a flowchart showing the operation of the tree measuring device according to the first embodiment. [Figure 8] FIG. 10 is a functional block diagram showing a configuration in which a control unit of a tree measurement device and a control unit of an aircraft cooperate with each other in a tree measurement system according to a second embodiment. [Figure 9] 10 is a flowchart showing processing when capturing an image of a tree in the tree measurement system according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] (First embodiment of the present invention) A tree measurement device according to this embodiment and a tree measurement system using this tree measurement device will be described with reference to Figures 1 to 7. The tree measurement device and tree measurement system according to this embodiment use an aircraft such as a drone to capture images of trees from the sky with far-infrared rays, and then perform image analysis of the captured data to measure the state of withering or growth of trees affected by oak wilt, etc.

[0015] FIG. 1 is a schematic diagram showing the system configuration of a tree measurement system according to this embodiment. In FIG. 1, the tree measurement system 1 includes a tree measurement device 10 capable of capturing images of a tree F to be measured using at least far-infrared light; an aircraft 20 carrying the tree measurement device 10; and a management device 30 that manages the measurement results of the tree measurement device 10, manages the flight operation of the aircraft 20, and manages the tree measurement system 1 as a whole. The aircraft 20 is not a required component. For example, the tree measurement device 10 may be installed in a fixed location like a fixed camera to capture images of the tree F, or the tree F may be captured while held by a person performing the measurement. The aircraft 20 and the tree measurement device 10 may also be integrated into one unit. In the tree measurement system 1 shown in FIG. 1, the tree measurement device 10, the aircraft 20, and the management device 30 are all connected to each other so as to be able to communicate wirelessly, and the devices work together to perform the processes described below.

[0016] The control means for controlling the flying object 20 is preset with condition information relating to conditions such as flight path, flight speed, and timing of flight start (measurement start), and the flight operation of the flying object 20 is controlled based on this set condition information. Furthermore, the control means for controlling the tree measuring device 10 is preset with condition information relating to conditions such as imaging position, imaging direction (imaging angle), and imaging timing, and the imaging operation of the tree measuring device 10 is controlled based on this set condition information. The control of the flying object 20 and the control processing of the tree measuring device 10 will be described in detail below. The management device 30 is a computer that visualizes and analyzes the measurement results measured by the tree measuring device 10, and can be, for example, a personal computer or tablet.

[0017] In addition, the condition information for controlling the flying object 20 and the condition information for controlling the tree measuring device 10 may be configured to be stored in the flying object 20 and the tree measuring device 10, respectively, as described above, or may be stored in the management device 30 and transmitted to the flying object 20 and the tree measuring device 10 as needed.

[0018] Fig. 2 is a schematic diagram showing the hardware configuration of a tree measurement device according to this embodiment. In Fig. 2, tree measurement device 10 includes a camera 11 (visible light imaging means) that captures an image of a target tree F and its surrounding area using visible light, a thermal sensor 12 (far-infrared imaging means) that detects and captures far-infrared light emitted by tree F, a control unit 13 that performs image analysis on the image information captured by camera 11 and thermal sensor 12, and controls the overall processing of the device, such as determining the growth state (withered state / growing state) of each tree F and controlling each sensor, an input / output interface 14 for inputting and outputting data to and from external devices, and a communication interface 15 for communicating with external devices via wired or wireless connections.

[0019] The camera 11 is an image sensor that captures images of the tree F, and captures images in a normal imaging mode using visible light such as sunlight as a light source. If the tree measurement device 10 is configured to include a near-infrared LED as needed, the camera may be configured to capture images in a night imaging mode using near-infrared light rays using the LED as a light source. In this case, when capturing images in the normal imaging mode, the light passes through a filter that cuts out near-infrared light rays, and when capturing images in the night imaging mode, the filter that cuts out near-infrared light rays can be removed to capture images.

[0020] The thermal sensor 12 detects far-infrared rays and detects the temperature according to their strength. Generally, the stronger the far-infrared rays, the higher the temperature, which is displayed in red, and the weaker the far-infrared rays, the lower the temperature, which is displayed in blue. In other words, the temperature distribution of the trees F can be detected for each individual tree.

[0021] The control unit 13 is composed of arithmetic processing devices such as a CPU, MPU, and MCU, and controls the entire tree measurement device 10. The processing of this control unit 13 will be described in detail later. The input / output interface 14 is an interface for connecting to external devices such as a power supply. The communication interface 15 is an interface for communicating with the flying object 20 and the management device 30, and is capable of wireless communication such as Wi-Fi, Bluetooth (registered trademark), and LTE.

[0022] 3 is a functional block diagram showing the configuration of the control unit in the tree measuring device according to this embodiment. The control unit 13 includes an image acquisition unit 41 that acquires a visible light image VI captured by the camera 11 and a far-infrared image IN detected by the thermal sensor 12, a growth determination unit 42 that determines whether the growth state of the tree F is alive or dead based on the difference between a first far-infrared image IN1 of the tree F captured at a first timing and a second far-infrared image IN2 of the tree F captured at a second timing, a dead tree identification unit 43 that identifies a dead tree F based on the visible light image VI and a difference image IN3 between the first far-infrared image IN1 and the second far-infrared image IN2 generated by the growth determination unit 42, and the dead tree identification unit 43. Finally, a result transmission unit 44 that transmits result information including at least the processing results of the growth determination unit 42 and the dead tree identification unit 43 to the management device 30.

[0023] The thermal sensor 12 of the tree measuring device 10 captures a first far-infrared image IN1 at a first timing and a second far-infrared image IN2 at a second timing. At this time, the camera 11 captures a visible light image VI at the same timing as the first timing or the second timing. The first far-infrared image IN1 and the second far-infrared image IN2 are captured by the thermal sensor 12 at the same imaging position and from the same imaging direction (imaging angle). This imaging information is sent to the image acquisition unit 41 of the control unit 13.

[0024] The growth determination unit 42 generates a difference image IN3 that shows the difference between the first far-infrared image IN1 and the second far-infrared image IN2 acquired by the image acquisition unit 41. If the representative value shown in this difference image IN3 is equal to or greater than a predetermined value, i.e., the difference between the first far-infrared image IN1 and the second far-infrared image IN2 is large, the tree F is determined to be in a dead state, and if the representative value shown in the difference image IN3 is less than the predetermined value, i.e., the difference between the first far-infrared image IN1 and the second far-infrared image IN2 is small, the tree F is determined to be in a growing state. In this case, the greater the difference between the outside air temperature around the tree F at the first timing and the outside air temperature around the tree F at the second timing, the more accurate the processing by the growth determination unit 42 becomes.

[0025] For example, suppose that at a first time point, the outside air temperature around tree F is T1, and the representative value of the temperature distribution of tree F measured by thermal sensor 12 at this time is t1. Also, suppose that at a second time point, the outside air temperature around tree F is T2, and the representative value of the temperature distribution of tree F measured by thermal sensor 12 at this time is t2. When tree F is growing, vital activities such as water circulation are occurring on the surface and inside of tree F, making tree F less susceptible to changes in outside air temperature (T1-T2). In other words, t1 and t2 are relatively close in value, and the value of t1-t2 is less than a predetermined value. In contrast, when tree F is growing in a dead state, vital activities are not occurring on the surface and inside of tree F, making tree F more susceptible to changes in outside air temperature (T1-T2). In other words, t1 and t2 are divergent in value, and the value of t1-t2 is greater than or equal to a predetermined value. That is, it is possible to determine the growth state of the tree F based on the difference between the first far-infrared image IN1 at the first timing and the second far-infrared image IN2 at the second timing.

[0026] As described above, the growth state of the tree F may be determined simply based on the magnitude of the difference (predetermined threshold) between the first far-infrared image IN1 and the second far-infrared image IN2, or may be determined based on the magnitude of the difference between the representative value t1 and the representative value t2 relative to the difference between the outside air temperatures T1 and T2. In this case, as shown in Fig. 3, temperature information 50, which is information about the outside air temperature, is input to the growth determination unit 42. For example, when the change in the outside air temperature (T1-T2) is 10°C, the tree F is determined to be in the withered state if t1-t2 is 5°C or higher and in the growing state if it is less than 5°C; and when the change in the outside air temperature (T1-T2) is 5°C, the tree F is determined to be in the withered state if t1-t2 is 2.5°C or higher and in the growing state if it is less than 2.5°C. In this way, it is desirable to change the reference threshold according to the change in the outside air temperature.

[0027] Furthermore, when multiple trees are included in the trees F, the state of growth may be determined by relatively comparing one tree with the other trees. For example, a representative value of the difference image IN3 between the first far-infrared image IN1 and the second far-infrared image IN2 may be calculated for each tree, and if the representative value of one tree is relatively larger than the other trees, the state of growth of the tree may be determined to be dead.

[0028] 4 and 5 are diagrams showing examples of a far-infrared image and a difference image in the tree measuring device according to this embodiment. FIG. 4 is a diagram showing an image of a growing tree F, and FIG. 5 is a diagram showing an image of a dead tree F. In FIG. 4, FIG. 4(A) is a first far-infrared image IN1 of the growing tree F, FIG. 4(B) is a second far-infrared image IN2 of the growing tree F, and FIG. 4(C) is an example of a difference image IN3 between FIGS. 4(A) and 4(B). Also, in FIG. 5, FIG. 5(A) is a first far-infrared image IN1 of the dead tree F, FIG. 5(B) is a second far-infrared image IN2 of the dead tree F, and FIG. 5(C) is an example of a difference image IN3 between FIGS. 5(A) and 5(B). In Figures 4 and 5, it is assumed that there is a predetermined temperature difference between the outside air temperature T1 at the first timing when the first far-infrared image IN1 is captured and the outside air temperature T2 at the second timing when the second far-infrared image IN2 is captured.

[0029] As described above, a growing tree F is relatively resistant to changes in outside air temperature, and therefore, as shown in Fig. 4(C), the difference (e.g., the sum, average, etc. of pixel values) between the first far-infrared image IN1 and the second far-infrared image IN2 is small. In contrast, a dead tree F is more susceptible to changes in outside air temperature, and therefore, as shown in Fig. 5(C), the difference (e.g., the sum, average, etc. of pixel values) between the first far-infrared image IN1 and the second far-infrared image IN2 is large. In other words, by performing image processing as shown in Figs. 4 and 5, the growth determination unit 42 can determine that the tree F shown in the image of Fig. 4(C) is growing and that the tree F shown in the image of Fig. 5(C) is dead.

[0030] The dead tree identification unit 43 superimposes the difference image IN3 of FIG. 5(C) on the visible light image VI acquired by the image acquisition unit 41 for a tree F determined to be dead by the growth determination unit 42. FIGS. 6A and 6B show an example of an image when a dead tree is identified in the tree measurement device according to this embodiment. FIG. 6A shows the visible light image VI, FIG. 6B shows the difference image IN3 of the dead tree F, and FIG. 6C shows an image obtained by superimposing FIGS. 6A and 6B. As described above, the visible light image VI is captured by the camera 11 at either the first timing or the second timing. Therefore, the imaging position and imaging direction of each of the infrared images in FIGS. 5(A) to 5(C) are the same as the imaging position and imaging direction of the visible light image VI (assuming that the angle of view for capturing images is also set to be the same). In other words, as shown in Figure 6(C), by simply overlaying the difference image IN3 obtained in Figure 5(C) on the visible light image VI at the same size, it is possible to identify the dead tree F in the visible light image VI.

[0031] The result transmission unit 44 transmits information such as the image data acquired by the image acquisition unit 41, the determination results of the growth determination unit 42, and the identification results of the dead tree identification unit 43 to the management device 30 as needed. This transmission process may be performed periodically or irregularly, or may be performed continuously in real time.

[0032] The management device 30 uses the information transmitted from the tree measuring device 10 to visualize images such as those shown in FIGS. 4 to 6, and indicates the location of the dead tree (e.g., location information indicated by latitude and longitude, or the location of the dead tree on a map) and outputs it to a display or the like. For example, from a macro perspective, the location of the dead tree can be indicated on a map displayed in a PC browser or a map app on a tablet, and from a micro perspective, the actual location of the dead tree can be easily reached by displaying an overlay with a visible light image VI as shown in FIG. 6(C). The tree manager can refer to the information displayed on the display of the management device 30 and take action to deal with the actual dead tree.

[0033] When displaying the location of a dead tree on a map, the route from the current location to the dead tree may also be displayed. Furthermore, when carrying a mobile device such as a tablet and heading to the actual location of a dead tree, it may be difficult to pinpoint the dead tree in a forest or mountain path. In such cases, the dead tree may be clearly displayed using the AR (augmented reality) function by capturing an image of the surroundings using the camera function of the mobile device.

[0034] Next, the operation of the tree measuring device 10 will be described. Fig. 7 is a flowchart showing the operation of the tree measuring device according to this embodiment. First, the image acquisition unit 41 acquires a first far-infrared image IN1 in which a tree F is captured at a first timing (S1). The image acquisition unit 41 further acquires a second far-infrared image IN2 in which the same tree F is captured at the same imaging position and imaging direction (imaging angle) as the first far-infrared image IN1 at a second timing when the outside air temperature T1 at the first timing has changed by a predetermined value or more (S2). The image acquisition unit 41 also acquires a visible light image VI that is captured simultaneously with the far-infrared image at the first timing or the second timing.

[0035] The growth determination unit 42 generates a difference image IN3 between the first far-infrared image IN1 and the second far-infrared image IN2 (S3), and determines whether the tree F is in a growing state or a dead state based on whether a representative value indicated by this difference image IN3 exceeds a predetermined value (S4). The representative value here refers to, for example, the average value, median value, or intermediate value between the maximum and minimum values ​​of the pixel values ​​of the entire difference image IN3, or the average value, median value, or intermediate value between the maximum and minimum values ​​of the pixel values ​​of the tree F portion in the difference image. If the representative value exceeds the predetermined value, i.e., if there is a large difference between the first far-infrared image IN1 and the second far-infrared image IN2, it is determined that the tree F is significantly affected by changes in outside temperature (there is no metabolism, which is a vital activity), and the tree F is determined to be in a dead state. Conversely, if it is below the representative value, i.e., if the difference between the first far-infrared image IN1 and the second far-infrared image IN2 is small, it is determined that the tree F is not significantly affected by changes in outside temperature (it has metabolism, which is a life activity), and the tree F is determined to be in a growing state.

[0036] If the tree F is determined to be dead, the dead tree identification unit 43 superimposes the visible light image VI on the difference image IN3 in which the tree F determined to be dead is captured (S5), and identifies the position of the dead tree F in the visible light image VI (S6). The result transmission unit 44 transmits information related to the results obtained by the above process to the management device 30 (S7), and the process ends.

[0037] The management device 30 visualizes and analyzes the result information sent from the tree measurement device 10 (such as displaying the location of dead trees F on a map) and displays it on a display or the like to provide it to the system administrator.

[0038] The functions of the growth determination unit 42 and the dead tree identification unit 43 may be provided on the management device 30 side, rather than on the tree measurement device 10. In that case, the tree measurement device 10 may be configured to have the function of acquiring the first far-infrared image IN1, the second far-infrared image IN2, and the visible light image VI and transmitting them to the management device 30.

[0039] Furthermore, in the above, the growth judgment unit 42 judges whether the tree F is in a growing state or a dead state based on the representative value of the difference image IN3, but by dividing the threshold into more detailed stages, it may be possible to judge, in addition to the growing state / dead state, for example, "a state on the verge of dying" or "a state in which vital activity is weak."

[0040] Furthermore, the growth state may be determined from the temperature distribution state other than the representative value. For example, an area with large temperature changes may be determined as an area where vital activity is weakened, i.e., an area that has suffered a lot of damage from pests or the like.

[0041] Furthermore, if the thermal sensor 12 can continuously sense the tree F from the first timing to the second timing, the growth state may be determined based on the rate of temperature change (temperature change per unit time). Specifically, in an environment or tree where there is no difference between the first far-infrared image IN1 and the second far-infrared image IN2, whether the tree is growing or dead, the growth state may be determined by calculating the difference in characteristics of the process from the first far-infrared image IN1 to the second far-infrared image IN2 (for example, whether the temperature change is fast / slow, or the mode of the temperature change is different, etc.).

[0042] Furthermore, in forests or woodlands where trees vary greatly in height, the temperature change is not uniform between shaded and sunny areas. In principle, the temperature change is small in shaded areas and large in sunny areas. In other words, different thresholds for determining the growth state may be used for shaded and sunny areas, and the determination may be performed using separate processes. In this case, a shadow area may be determined as an area where the color (lightness or luminance) of the visible light image VI is darker than a predetermined value and the temperature of the far-infrared image is lower than a predetermined value. Alternatively, for example, the distance to the top of the tree F may be calculated as the difference in elevation based on the focus adjustment when capturing an image vertically from the sky, and a region where the tree F is low (i.e., a region where the distance from the image capturing position in the sky to the top of the tree F is long) may be regarded as a shadow region. Alternatively, when capturing an image from the sky, a distance sensor such as a laser rangefinder may be used to calculate the vertical distance to the top of the tree F as the difference in elevation, and a region where the tree F is low (i.e., a region where the distance from the image capturing position in the sky to the top of the tree F is long) may be regarded as a shadow region. Also, the position of the sun at the first timing and the position of the sun at the second timing may be taken into consideration. That is, the influence on the temperature difference due to the difference in angle between the sunlight irradiated at the first timing and the sunlight irradiated at the second timing may be eliminated by correction.

[0043] In this way, in the tree measuring device 10 of this embodiment, a first far-infrared image IN1 and a second far-infrared image IN2 are acquired for the tree F to be measured at different times, and the tree F for which the difference between the two far-infrared images is greater than a predetermined value is determined to be in a dead state.Therefore, if there is a large change in the far-infrared image representing temperature changes in relation to environmental changes around the tree F to be measured, it can be assumed that the tree is not metabolizing or is in a very poor metabolic state, and it can be determined whether the tree F to be measured is in a growing state or in a dead state.

[0044] Furthermore, for a tree F in which the difference between the first far-infrared image IN1 and the second far-infrared image IN2 is relatively large compared to other trees, the growth state of the tree F is determined to be dead, so the growth state of the tree F can be accurately determined from its relative relationship with the surrounding trees.

[0045] Furthermore, for a tree F for which the rate of change between the first far-infrared image IN1 and the second far-infrared image IN2 in response to the change in the outside air temperature T1 of the area where the tree F is located at the first time and the change in the outside air temperature T2 of the area where the tree F is located at the second time is greater than or equal to a predetermined value, the tree F is determined to be in a dead state, so that the growth state of the tree F can be accurately determined from the change in temperature of the tree F in response to the change in the outside air temperature.

[0046] (Second embodiment of the present invention) The second embodiment will be described below with reference to Fig. 8 and Fig. 9. As described in the first embodiment, in the present invention, it is desirable that the imaging mode when imaging a tree F at a first timing and the imaging mode when imaging a tree F at a second timing be the same. To achieve this, in this embodiment, the thermal sensor 12 captures a first far-infrared image IN1 at the first timing, and the camera 11 captures a visible light image VI, and then the visible light image VI is used for positioning to capture a second far-infrared image IN2 at the second timing.

[0047] Furthermore, in this embodiment, the tree measuring device 10 images the tree F while the flying object 20 flies along a preset flight path at a first timing when the outside air temperature is T1. When the series of imaging processes at the first timing is completed, the flying object 20 returns to the standby position and waits. Then, at a second timing when the outside air temperature reaches T2, the flying object 20 starts flying again, and the tree measuring device 10 images the tree F.

[0048] In other words, in this embodiment, the control unit of the aircraft 20 (not shown in Figure 1) and the control unit 13 of the tree measuring device 10 work together (work together as an imaging control means) to control each piece of equipment, making it possible to perform accurate flight control and tree measurement.

[0049] Figure 8 is a functional block diagram showing a configuration in which the control unit of the tree measurement device and the control unit of the flying object cooperate with each other in the tree measurement system according to this embodiment. In Figure 8, the control unit 21 of the flying object 20 includes a flight determination unit 22 that determines the start of flight at a first timing and the start of flight at a second timing based on temperature information 50, and a flight control unit 24 that controls the flight of the flying object 20 at the first timing and the second timing based on information stored in a flight information storage unit 23 in which information related to, for example, the flight path, flight speed, flight altitude, and other flight aspects is preset and registered.

[0050] 8, the control unit 13 of the tree measurement device 10 is equipped with an image acquisition unit 41 that acquires images captured by the camera 11 and thermal sensor 12 at a first timing and stores them in an image information storage unit 45, and also stores the imaging aspects of the camera 11 and thermal sensor 12 when these images were captured (e.g., imaging position, imaging direction, imaging angle, field angle size, etc.), and a calibration unit 46 that reads out information about the visible light image VI and imaging aspects stored in the image information storage unit 45 at a second timing and calibrates the thermal sensor 12 so that the imaging aspects are the same as the imaging aspects at the first timing. The calibration unit 46 also adjusts the imaging position of the flying object 20 by transmitting calibration information to the flight control unit 24 as necessary.

[0051] Then, the control unit 21 of the flying object 20 and the control unit 13 of the tree measurement device 10 cooperate to perform imaging at the second timing in the same imaging mode as the imaging mode at the first timing.

[0052] Note that the functional block diagram shown in Figure 3 shows only the minimum necessary configuration directly related to the process of determining the growth of tree F, and the functional block diagram shown in Figure 8 shows only the minimum necessary configuration directly related to the process of capturing an image of tree F, and other well-known configurations are omitted in both drawings.

[0053] FIG. 9 is a flowchart showing the process of capturing an image of a tree in the tree measurement system according to this embodiment. First, the flight determination unit 22 acquires the outside air temperature T1 at a first timing (S1). The flight control unit 24 starts the flight of the flying object 20 based on the information registered in the flight information storage unit 23 (S2). The thermal sensor 12 of the tree measurement device 10 captures a first far-infrared image IN1, and the camera 11 captures a visible light image VI (S3). The image acquisition unit 41 stores each image captured in S3 in the image information storage unit 45, and also stores information related to the image capturing mode at that time (S4). After completing a series of flights along the flight path registered in the flight information storage unit 23, the flying object 20 returns to a waiting location (S5).

[0054] The flight determination unit 22 acquires the outside air temperature T2 and determines whether T1-T2 is equal to or greater than a predetermined value (S6). If T1-T2 is less than the predetermined value, i.e., the temperature difference between the outside air temperature T1 at the first timing and the current outside air temperature T2 is small, the flying object 20 continues to wait (S7). If T1-T2 is equal to or greater than the predetermined value, i.e., the temperature difference between the outside air temperature T1 at the first timing and the current outside air temperature T2 is large, the current time is set as the second timing and flight begins (S8). The calibration unit 46 aligns the visible light image VI stored in the image information storage unit 45 with the real-time scenery captured by the camera 11, and determines the imaging mode of the thermal sensor 12 so that they match (S9). The thermal sensor 12 captures a second far-infrared image IN2 according to the determined imaging mode (S10). The image acquisition unit 41 acquires the second far-infrared image IN2 captured in S10 and stores it in the image information storage unit 45 (S11). When the aircraft 20 completes a series of flights along the flight path registered in the flight information storage unit 23, the processing ends.

[0055] In S6, the flight determination unit 22 acquires the outside air temperature T2 at the second timing and determines whether T1-T2 is equal to or greater than a predetermined value. This determination process may be performed periodically or irregularly based on preset information. Specifically, for example, the outside air temperature T2 may be acquired at a preset time, or when a predetermined time has elapsed since the first timing. Furthermore, if the first timing is set to a time when the temperature is low, such as in the morning or evening, the second timing may be set to a time during the day when the temperature is relatively high, or vice versa. Furthermore, if the first timing is set to a time when the weather is fine, the second timing may be set to a time after it has rained, or vice versa.

[0056] As described above, the tree measurement system of this embodiment includes a thermal sensor 12 that captures at least a far-infrared image of tree F, a control unit 13 that controls the imaging mode of the thermal sensor 12, an image acquisition unit 41 that acquires a first far-infrared image IN1 captured by the thermal sensor 12 at a first timing and a second far-infrared image IN2 captured by the tree F at a second timing, and a growth judgment unit 42 that judges the growth state of a tree F for which the difference between the acquired first far-infrared image IN1 and second far-infrared image IN2 is greater than or equal to a predetermined value to be in a dead state. The control unit 13 controls the thermal sensor 12 so that the imaging mode of the thermal sensor 12 at the second timing is the same as the imaging mode of the thermal sensor 12 at the first timing, so that the first far-infrared image IN1 and the second far-infrared image IN2 can be captured in the same imaging mode, and a difference image IN3 between them can be generated accurately and easily.

[0057] In addition, the device is equipped with a camera 11 that captures a visible light image VI of at least a tree F at the same first timing as the thermal sensor 12, and the control unit 13 uses the visible light image VI captured at the first timing to calibrate and control the imaging mode of the thermal sensor 12 at the second timing.Therefore, the imaging mode of the thermal sensor 12 at the first timing and the imaging mode of the thermal sensor 12 at the second timing can be accurately matched using the visible light image VI, and a difference image IN3 between the first far-infrared image IN1 and the second far-infrared image IN2 can be accurately and easily generated.

[0058] Furthermore, a tree measuring device 10 having a thermal sensor 12 is installed on an aircraft 20, a tree F is photographed from the thermal sensor 12 by aerial photography, and the control unit 21 of the aircraft 20 and the control unit 13 of the tree measuring device 10 work together to determine the second timing as the timing when the outside temperature T2 in the area where the tree F is located at a first timing and the difference between the outside temperature T1 and the outside temperature T2 is greater than a predetermined value, and control the aircraft 20 and the thermal sensor 12 so that the flight mode of the aircraft 20 and the imaging mode of the thermal sensor 12 are the same as those at the first timing, thereby making it possible to accurately and easily generate a difference image IN3 between the first far-infrared image IN1 and the second far-infrared image IN2 from the sky by an aircraft 20 such as a drone.

[0059] In the present invention, in the first stage, a neural network that has been thoroughly trained on far-infrared images of trees F in a growing state and far-infrared images of trees F in a dead state may be used to perform an AI-based assessment of the growth of the trees F, and in the second stage, the processing described in the first or second embodiment may be performed. Trees F that have been assessed as dead in either of these processes may then be formally assessed as dead. The first and second stage processes may be performed seasonally. For example, the first stage process may be performed in summer, and the second stage process may be performed in autumn or winter. This allows for more accurate assessment of dead trees. [Explanation of symbols]

[0060] 1. Tree measurement system 10 Tree measuring device 11 Camera 12 Thermal Sensor 13 Control Unit 14 Input / Output Interface 15 Communication Interface 20 Flying Objects 21 Control Unit 22 Flight Judgment Section 23 Flight information storage section 24 Flight control unit 30 Management device 41 Image acquisition unit 42 Development Judgment Department 43 Dead tree identification department 44 Result transmission unit 45 Image information storage unit 46 Calibration section 50 Temperature Information

Claims

1. an image acquisition means for acquiring at least a first far-infrared image of a tree captured at a first timing and a second far-infrared image of the tree captured at a second timing; A tree measuring device characterized by comprising a growth determination means for determining that the growth state of a tree is dead for trees for which the difference between the acquired first far-infrared image and the acquired second far-infrared image is greater than a predetermined value.

2. The tree measuring device according to claim 1, The growth determination means A tree measuring device characterized in that, for a tree for which the difference between the first far-infrared image and the second far-infrared image is relatively large compared to other trees, the growth state of the tree is determined to be dead.

3. The tree measuring device according to claim 1 or 2, The growth determination means A tree measuring device characterized by determining that a tree is dead when the rate of change between the first far-infrared image and the second far-infrared image relative to the change between a first outside air temperature in the area where the tree is located at the first timing and a second outside air temperature in the area where the tree is located at the second timing is greater than a predetermined value.

4. a far-infrared imaging means for capturing a far-infrared image of at least a tree; an imaging control means for controlling the imaging mode of the far-infrared imaging means; an image acquisition means for acquiring at least a first far-infrared image of the tree captured by the far-infrared imaging means at a first timing and a second far-infrared image of the tree captured by the far-infrared imaging means at a second timing; a growth determination means for determining that a growth state of a tree is dead when a difference between the acquired first far-infrared image and the acquired second far-infrared image is equal to or greater than a predetermined value, A tree measurement system characterized in that the imaging control means controls the far-infrared imaging means so that the imaging mode of the far-infrared imaging means at the second timing is the same as the imaging mode of the far-infrared imaging means at the first timing.

5. 5. The tree measurement system according to claim 4, a visible light imaging means for capturing a visible light image of at least the tree at the same first timing as the far-infrared imaging means; The imaging control means A tree measurement system characterized in that the imaging mode of the far-infrared imaging means at the second timing is calibrated and controlled using the visible light image captured at the first timing.

6. 6. The tree measurement system according to claim 4 or 5, the far-infrared imaging means is installed on an aircraft, and the tree is imaged from the far-infrared imaging means by aerial photography; A tree measurement system characterized in that the imaging control means and the control means of the aircraft control the second timing, which is the timing when the difference between the first outside air temperature in the area where the tree is located at the first timing and the second outside air temperature is greater than a predetermined value, and control the aircraft and the far-infrared imaging means so that the flight behavior of the aircraft and the imaging behavior of the far-infrared imaging means are the same as those at the first timing.

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