Forest management systems and forest management methods

Abstract

To manage the state of trees constituting forestry.SOLUTION: A low-altitude observation machine comprises: a ranging device for generating a distance map; and a positioning device for measuring the position of the low-altitude observation machine. The low-altitude observation machine moves in a region of a forest near the ground without branches or leaves. The low-altitude distance map generated by the ranging device and the position of the low-altitude observation machine are acquired by a data acquisition unit from the low-altitude observation machine. The position of a tree is specified by a position-specifying unit on the basis of the position of the low-altitude observation machine and the distance from the low-altitude observation machine to the tree specified on the basis of the low-altitude distance map. Identification information for identifying an individual tree on the basis of the position of the tree is acquired by an identification unit. Low-altitude tree information, which is information on the tree at a portion lower than branches and leaves of the individual measured on the basis of the low-altitude distance map, is recorded by a recording unit in a database in association with the identification information.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a forest management system and a forest management method. Background Art

[0002] Patent Document 1 discloses a technology of recognizing topography of a work site and planning a movement route for a forestry machine for timber harvesting based on images of the work site acquired by imaging with an unmanned aerial vehicle. Prior Art Literature Patent Literature

[0003] Patent Document 1 U.S. Pat. No. 10322803 Specification Summary of the Invention Problem to be Solved by the Invention

[0004] When trees are densely grown in a forest, the tree canopy appears in images captured from above the forest, and there is a possibility that portions of trees below the canopy do not appear in the images. In addition, trees that do not form part of the canopy do not appear in images captured from above the forest, and there is a possibility that the conditions of such trees cannot be managed. An object of the present disclosure is to provide a forest management system and a forest management method that can manage the conditions of trees constituting a forest. Means for Solving the Problem

[0005] According to one aspect of the present invention, the forest management system includes a data acquisition unit that acquires the low-altitude distance map generated by a distance measuring device and the position of a low-altitude observation device from a low-altitude observation device equipped with a distance measuring device that generates a distance map and a positioning device that measures its own position, which moves through an area of ​​the forest near the ground surface where there are no branches or leaves; a position identification unit that identifies the position of a tree based on the distance from the low-altitude observation device to the tree identified based on the low-altitude distance map and the position of the low-altitude observation device; an identification unit that acquires identification information to identify an individual tree based on the position of the tree; and a recording unit that records low-altitude tree information, which is tree information of the part of the individual tree that is lower than the branches and leaves measured based on the low-altitude distance map, in a database in association with the identification information. [Effects of the Invention]

[0006] According to the above embodiment, the forest management system can manage the condition of the trees that make up the forest. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram showing a forest management system according to the first embodiment. [Figure 2] This is a configuration diagram showing the external appearance of a low-altitude observation aircraft according to the first embodiment. [Figure 3] This is a diagram showing the external appearance of a high-altitude observation aircraft according to the first embodiment. [Figure 4] This is a configuration diagram showing the external appearance of a forestry machine according to the first embodiment. [Figure 5] This is a schematic block diagram showing the configuration of the forest management device according to the first embodiment. [Figure 6] This figure shows the database stored by the storage according to the first embodiment. [Figure 7] This is a flowchart showing the tree information update process by the forest management device according to the first embodiment. [Figure 8] This is a flowchart showing the process of generating a logging plan by the forest management device according to the first embodiment. [Figure 9]This is a schematic block diagram showing the configuration of the forest management device according to the second embodiment. [Modes for carrying out the invention]

[0008] <First Embodiment> 《Configuration of Forest Management Systems》 The embodiments will be described in detail below with reference to the drawings. Figure 1 is a schematic diagram showing the forest management system 1 according to the first embodiment. The forest management system 1 identifies individual trees growing in forest F and manages the status of each individual tree. The forest management system 1 also generates a harvesting plan based on the status of the trees and carries out the harvesting. The forest management system 1 includes a low-altitude observation device 10, a high-altitude observation device 30, forestry machinery 50, and a forest management device 70.

[0009] The low-altitude observation aircraft 10 travels on the ground of forest F by remote control and observes the trunks of trees and the ground surface growing in forest F. As shown in Figure 1, the low-altitude observation aircraft 10 according to the first embodiment may be a robot equipped with caterpillar tracks. The low-altitude observation aircraft 10 according to other embodiments may be a vehicle that travels on wheels or legs, or a drone that flies through the air. When the low-altitude observation aircraft 10 is flying, it flies at an altitude lower than the canopy of forest F. The canopy refers to the part of the forest where branches and leaves grow. In other words, the low-altitude observation aircraft 10 flies in the area near the ground surface of forest F where there are no branches or leaves.

[0010] The high-altitude observation aircraft 30 flies over forest F via remote control and observes the tree canopy of trees growing in forest F. The tree canopy refers to the part of the tree where the branches and leaves grow. Remote control may be performed by an operator in real time via controller C3, or the operator may fly along a pre-set route using controller C3. In other words, the high-altitude observation aircraft 30 flies at an altitude higher than the canopy of forest F. As shown in Figure 1, the high-altitude observation aircraft 30 according to the first embodiment may be a drone.

[0011] The forestry machine 50 is a work machine that grasps the trunk of a tree, cuts it down, and can move while holding the trunk. This allows the forestry machine 50 to accumulate the timber in a designated location. The forestry machine 50 may be a feller buncher or a harvester.

[0012] The forest management device 70 receives measurement data from the low-altitude observation device 10 and the high-altitude observation device 30, identifies individual trees inhabiting forest F, and records the status of each individual tree. The forest management device 70 also generates a harvesting plan based on the status of the trees and transmits instruction signals to the forestry machinery 50. The forestry machinery 50 operates based on the instruction signals received from the forest management device 70. The low-altitude observation device 10, the high-altitude observation device 30, the forestry machinery 50, and the forest management device 70 are connected to each other via a communication network N such as the Internet. The forest management device 70 may be installed remotely from the low-altitude observation device 10, the high-altitude observation device 30, and the forestry machinery 50.

[0013] 《Configuration of the Low-Altitude Observation Aircraft 10》 Figure 2 is a configuration diagram showing the external appearance of the low-altitude observation aircraft 10 according to the first embodiment. The low-altitude observation aircraft 10 comprises a running gear 11 and an airframe 12. The running gear 11 supports the airframe 12 so that it can move. The running gear 11 of the low-altitude observation aircraft 10 may be, for example, an endless track driven by the power of a motor.

[0014] The aircraft body 12 is equipped with a rangefinder 121, a positioning device 122, an attitude measuring device 123, an illuminance sensor 124, a battery 125, a control device 126, and an imaging device 127. The ranging device 121 generates a distance map in which distances to objects within the field of view are mapped. Examples of the ranging device 121 include a stereo camera, a ToF camera, a pattern projection camera, and LiDAR. The imaging device 127 captures a color image of a subject. The ranging device 121 and the imaging device 127 are provided such that their lines of sight face forward of the airframe 12. Note that when the ranging device 121 can acquire a color image, for example in a case where the ranging device 121 is a stereo camera, the airframe 12 may not include the imaging device 127. A distance map is data obtained by mapping distances at a plurality of points on a two-dimensional plane. The distance map includes, for example, three-dimensional shape data generated by LiDAR or the like and a distance image generated by a stereo camera.

[0015] The positioning device 122 includes an antenna that receives positioning signals from GNSS, and measures the position of the low-altitude observation aircraft 10 based on the positioning signals received via the antenna. The positioning device 122 outputs position data indicating the measured position to the control device 126. The position of the low-altitude observation aircraft 10 is represented in a three-dimensional global coordinate system. When the positioning device 122 includes a plurality of antennas, the positioning device 122 can measure the azimuth direction in which the low-altitude observation aircraft 10 is facing. The attitude measurement device 123 measures the attitude of the airframe 12. Specifically, the attitude measurement device 123 measures the pitch angle, roll angle, and yaw angle of the airframe 12 based on acceleration and angular acceleration measured by a built-in IMU (Inertial Measurement Unit). When the IMU includes a geomagnetic sensor, the attitude measurement device 123 can measure the attitude in the global coordinate system. On the other hand, the attitude measurement device 123 may measure the attitude in a local coordinate system with reference to the airframe 12, and convert the attitude to the global coordinate system based on the azimuth direction in which the airframe 12 is facing measured by the positioning device 122.

[0016] The illuminance sensor 124 is provided on the upper surface of the airframe 12, and measures the brightness around the low-altitude observation aircraft 10. The battery 125 is a power source for the traveling device 11 and the control device 126.

[0017] The control device 126 receives control signals for the travel device 11 from the controller C1, which remotely operates the low-altitude observation aircraft 10, and drives the travel device 11 according to the control signals. The controller C1 may be a PC or a smartphone. The control device 126 transmits to the controller C1 an image of the distance map generated by the rangefinder 121 or an image captured by the imaging device 127. The control device 126 also receives measurement instruction signals from the controller C1 instructing the measurement of the state of the trees. For example, the operator operates the controller C1 to point the front of the low-altitude observation aircraft 10 towards the tree to be measured and transmits the measurement instruction signal. In other words, the operator controls the attitude of the low-altitude observation aircraft 10 so that the tree is in the center of the image and transmits the measurement instruction signal. After receiving the measurement instruction signal, the control device 126 transmits the measurement data acquired by the distance measuring device 121, positioning device 122, attitude measuring device 123, and illuminance sensor 124 to the forest management device 70, associating it with the time of measurement.

[0018] Configuration of the 30 High-Altitude Observation Vehicles Figure 3 is a diagram showing the external appearance of the high-altitude observation aircraft 30 according to the first embodiment. The high-altitude observation aircraft 30 comprises a fuselage 31 and a propeller 32. The propeller 32 is mounted on the top of the fuselage 31 and generates lift through rotation. The fuselage 31 is equipped with a rangefinder 311, a multispectral camera 312, a positioning device 313, an attitude measuring device 314, an illuminance sensor 315, a battery 316, and a control device 317.

[0019] The rangefinder 311 generates a distance map that maps the distance to the subject within the field of view. Examples of rangefinders 311 include stereo cameras, ToF cameras, and LiDAR. The rangefinder 311 is positioned so that its line of sight is directed downwards from the aircraft 31. The multispectral camera 312 measures the intensity of reflected light at multiple wavelengths from the visible to the infrared region and generates data cubes representing the captured images for each wavelength. A data cube is three-dimensional data formed by arranging two-dimensional image data, represented by the X and Y axes, on the wavelength axis. The multispectral camera 312 acquires images in the visible region, which is used for photosynthesis, and images in the near-infrared region, which is not used for photosynthesis. The multispectral camera 312 is positioned so that its line of sight is directed downwards from the aircraft 31.

[0020] The positioning device 313 is equipped with an antenna that receives positioning signals from GNSS and measures the position of the high-altitude observation aircraft 30 based on the positioning signals received via the antenna. The positioning device 313 outputs position data indicating the measured position to the control device 317. The position of the high-altitude observation aircraft 30 is represented in a three-dimensional global coordinate system. If the positioning device 313 is equipped with multiple antennas, the positioning device 313 can measure the direction the high-altitude observation aircraft 30 is facing. The attitude measurement device 314 measures the attitude of the aircraft 31. Specifically, the attitude measurement device 314 measures the pitch angle, roll angle, and yaw angle of the aircraft 31 based on the acceleration and angular acceleration measured by the built-in IMU. If the IMU includes a geomagnetic sensor, the attitude measurement device 314 can measure the attitude in a global coordinate system. On the other hand, the attitude measurement device 314 may measure the attitude in a local coordinate system based on the aircraft 31 and convert it to a global coordinate system based on the direction the aircraft 31 is facing, as measured by the positioning device 313.

[0021] The illuminance sensor 315 is mounted on the upper surface of the aircraft body 31 and measures the brightness around the high-altitude observation aircraft 30. The battery 316 is the power source for the motor and control device 317 that drive the propeller 32.

[0022] The control device 317 receives control signals from the controller C3, which remotely operates the high-altitude observation aircraft 30, and drives the propellers 32 according to these control signals. The controller C3 may be a PC or a smartphone. The control device 317 may also transmit to the controller C3 an image of the distance map captured by the ranging device 311, or a color image of the data cube captured by the multispectral camera 312. In another embodiment, the high-altitude observation aircraft 30 may move in conjunction with the low-altitude observation aircraft 10 while maintaining their planar position. In this case, the control device 317 may determine the direction of movement based on the position data measured by the positioning device 313 and the position data of the low-altitude observation aircraft 10, and drive the propellers 32. The control device 317 also receives a measurement instruction signal from the controller C3 instructing it to measure the condition of the trees below. That is, the operator operates the controller C3 to position the high-altitude observation aircraft 30 directly above the trees to be measured and transmits the measurement instruction signal. In other words, the operator controls the high-altitude observation aircraft 30 so that the tree to be measured is in the center of the image, and then transmits a measurement instruction signal. The control device 317 transmits the measurement data acquired by the distance measuring device 311, the multispectral camera 312, the positioning device 313, the attitude measuring device 314, and the illuminance sensor 315 to the forest management device 70, associating it with the time of measurement.

[0023] 《Composition of 50 Forestry Machines》 Figure 4 is a diagram showing the external appearance of the forestry machine 50 according to the first embodiment. The forestry machine 50 comprises a vehicle body 51, a travel device 52, a work implement 53, and a control device 54.

[0024] The running gear 52 supports the vehicle body 51 so that it can move. The running gear 52 is a continuous track driven by the power of the engine. On the other hand, in other embodiments, the running gear 52 may be equipped with wheels driven by the power of the engine.

[0025] The vehicle body 51 is equipped with a positioning device 511 for measuring the position of the vehicle body 51. The positioning device 511 has an antenna that receives positioning signals from GNSS and measures the position of the vehicle body 51 based on the positioning signals received via the antenna. The positioning device 511 outputs position data indicating the measured position to the control device 54. The position of the vehicle body 51 is represented in a three-dimensional global coordinate system.

[0026] The work implement 53 is used for gripping and felling trees. The work implement 53 is mounted on the front of the vehicle body 51. The work implement 53 comprises a boom 531, an arm 532, a head 533, an arm cylinder 534, and a head cylinder 535.

[0027] The base end of the boom 531 is attached to the rear of the vehicle body 51. The boom 531 is rotated by a hydraulic motor (not shown). The base end of the arm 532 is rotatably attached to the tip of the boom 531 around an axis extending in the width direction of the vehicle body 51. The head 533 is rotatably attached to the arm 532 around a first axis extending in the width direction of the vehicle body 51, and also rotatably around a second axis perpendicular to the first axis. A grapple 5331 for gripping trees is provided on the upper part of the head 533. A circular saw 5332 for felling trees is provided on the lower part of the head 533 parallel to the grapple 5331.

[0028] The arm cylinder 534 and head cylinder 535 are hydraulic cylinders. The base end of the arm cylinder 534 is attached to the boom 531. The tip end of the arm cylinder 534 is attached to the arm 532. The arm 532 moves up and down as the arm cylinder 534 extends and retracts due to the hydraulic fluid. The base end of the head cylinder 535 is attached to the arm 532. The tip end of the head cylinder 535 is attached to the head 533. The head 533 rotates around the first axis as the head cylinder 535 extends and retracts due to the hydraulic fluid.

[0029] The control device 54 generates drive signals to drive the traveling device 52 and the work machine 53, and controls the actuators of the traveling device 52 and the work machine 53. The control device 54 is equipped with a communication device that communicates with the forest management device 70 via the communication network N. The control device 54 controls the traveling device 52 and the work machine 53 based on instruction signals received from the forest management device 70 via the communication network N and position data measured by the positioning device 511. The instruction signals received from the forest management device 70 include the travel route in the forest F, as well as identification information and location information of the trees to be felled. The control device 54 drives the traveling device 52 along the travel route based on the position data measured by the positioning device 511. The control device 54 also drives the traveling device 52 so that it faces the trees directly based on the position data and drives the work machine 53. When the felling of a tree is completed, the control device 54 transmits a felling notification signal containing the identification information of the tree to the forest management device 70.

[0030] Configuration of Forest Management System 70 Figure 5 is a schematic block diagram showing the configuration of the forest management device 70 according to the first embodiment. The forest management device 70 is a computer equipped with a processor 71, main memory 73, storage 75, and interface 77. The storage 75 stores programs. The processor 71 reads programs from the storage 75, loads them into the main memory 73, and executes processing according to the programs. In other embodiments, the forest management device 70 may include, in addition to or instead of the above configuration, a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device). Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions realized by the processor 71 may be realized by the integrated circuit. Such an integrated circuit is also included as an example of a processor.

[0031] The forest management device 70 is connected to the communication network N via interface 77. The forest management device 70 is also connected to an input / output device (not shown) via interface 77. Examples of storage 75 include HDDs (Hard Disk Drives), SSDs (Solid State Drives), and non-volatile memory. Storage 75 may be an internal medium directly connected to the bus of the forest management device 70, or it may be an external medium connected to the forest management device 70 via an interface 77. Storage 75 is a tangible, non-temporary storage medium.

[0032] Storage 75 contains a database 751 that stores information about individual trees growing in forest F. Figure 6 shows the database stored by the storage according to the first embodiment. Specifically, the database 751 stores, for each individual tree, the ID, location, type, height, diameter, activity level, defects, relative brightness of the surroundings, age, timber volume, image, presence or absence of planting, and logging status, associated with each individual tree. The ID is identification information for identifying an individual tree. The location is the three-dimensional position in the global coordinate system where the tree exists. That is, the location is the latitude, longitude, and elevation of the ground surface on which the tree stands. The height is the length from the ground surface to the treetop. The activity level is an index value of the tree's photosynthetic activity. The activity level is expressed, for example, by NDVI (Normalized Difference Vegetation Index), which is the ratio of the amount of reflected light in the red wavelength region to the amount of reflected light in the near-infrared region. Defects indicate the presence or absence of bark peeling or decay. Relative illumination is the ratio of illumination below the canopy to illumination above the canopy. Logging status indicates whether or not the tree has been felled. The presence or absence of planting may be obtained from an external database not shown in the diagram, and in that case, data on planting, such as information on the time, location, and type of planting, may be obtained and used to update the tree age, location, and type in this database 751.

[0033] The processor 71, by executing a program, functions as a data acquisition unit 711, a location identification unit 712, a fallen tree determination unit 713, an identification unit 714, a tree head height calculation unit 715, a tree height calculation unit 716, a diameter calculation unit 717, a type identification unit 718, a defect identification unit 719, an activity level calculation unit 720, a relative light intensity calculation unit 721, a recording unit 722, a logging plan generation unit 723, and a logging instruction unit 724.

[0034] The data acquisition unit 711 acquires measurement data from the low-altitude observation aircraft 10 and the high-altitude observation aircraft 30. Specifically, the data acquisition unit 711 acquires the distance map (low-altitude imaging data) acquired by the low-altitude observation aircraft 10, as well as the time, position, attitude, and illuminance at the time of imaging. The distance map of the low-altitude observation aircraft 10 may be imaged so that a tree is visible in the center. Hereinafter, the central point in the distance map will also be referred to as the point of interest. In other embodiments, the processor 71 may analyze the distance map or the image captured by the imaging device 127 and identify the point where a tree exists as the point of interest. For example, if an object with a shape similar to a tree trunk, a semi-cylindrical shape, etc., is recognized in the measured distance map, that object may be recognized as a tree, and furthermore, if an object similar to a tree is imaged in that direction in the image, that object may be recognized as a tree. The data acquisition unit 711 also acquires the distance map and data cube (high-altitude imaging data) acquired by the high-altitude observation aircraft 30, as well as the time, position, attitude, and illuminance at the time of imaging.

[0035] The positioning unit 712 identifies the three-dimensional position of the lower end of the tree from the position and attitude of the low-altitude observation aircraft 10 acquired by the data acquisition unit 711, as well as from the distance map. Specifically, the data acquisition unit 711 identifies the three-dimensional position of the lower end of the tree using the following procedure. The positioning unit 712 identifies the portion in which a semi-cylindrical structure is captured by pattern matching of the distance map of the low-altitude observation aircraft 10. Next, the positioning unit 712 identifies the point in which the axial end of the said structure is captured. Since the treetop is not visible in the field of view of the rangefinder 121 of the low-altitude observation aircraft 10, it is estimated that the axial end of the tree is the lower end of the tree. The positioning unit 712 identifies the three-dimensional position of the identified point based on the position and attitude of the low-altitude observation aircraft 10. If the tree is a living tree, the position of the lower end of the tree is the position of the ground surface on which the tree stands. The altitude of the ground surface on which the tree stands is one of the tree information items for the part of the tree lower than the trunk.

[0036] The fallen tree determination unit 713 determines whether a tree identified by the position identification unit 712 is a fallen tree or a living tree, based on the distance map of the low-altitude observation aircraft 10 acquired by the data acquisition unit 711. Specifically, the fallen tree determination unit 713 identifies the axis direction of the tree from the distance map and determines that the tree is a fallen tree if the angle between the axis direction and the horizontal plane is less than a predetermined fallen tree determination threshold, i.e., if the axis direction of the tree is close to horizontal. On the other hand, the fallen tree determination unit 713 determines that the tree is a living tree if the angle between the axis direction and the horizontal plane is greater than or equal to the fallen tree determination threshold. The fallen tree determination unit 713 may record the location of the tree determined to be a fallen tree in the database 751.

[0037] The identification unit 714 obtains the ID of a tree that has been determined to be a living tree by the fallen tree determination unit 713. Specifically, the identification unit 714 identifies an uncut tree from the database 751 that is closest to the latitude and longitude of the tree identified by the location identification unit 712. If the distance to this tree is less than a predetermined error threshold, the identification unit 714 determines that the tree shown on the distance map is that tree and obtains its ID. On the other hand, if the distance to the closest tree is greater than or equal to the error threshold, the identification unit 714 determines that the tree shown on the distance map is a new tree and assigns a new ID to it. When the identification unit 714 assigns a new ID to a tree, it associates the planar position identified by the location identification unit 712 with the ID and records it in the database 751.

[0038] Furthermore, the treetop altitude calculation unit 715 calculates the altitude of the treetops from the distance map of the high-altitude observation aircraft 30 acquired by the data acquisition unit 711. Specifically, the treetop altitude calculation unit 715 calculates the altitude of the treetops using the following procedure. The treetop altitude calculation unit 715 identifies the point where the treetops are visible from the distance map of the high-altitude observation aircraft 30. For example, the treetop altitude calculation unit 715 may identify the point where the height is maximum in the distance map as the point where the treetops are visible. Next, the treetop altitude calculation unit 715 calculates the three-dimensional position of the point where the treetops are visible based on the position and attitude of the high-altitude observation aircraft 30 at the time of imaging. The identification unit 714 identifies an uncut tree from the database 751 that is closest to the latitude and longitude of the point where the treetops are visible. Then, the treetop altitude calculation unit 715 identifies the altitude of the calculated three-dimensional position as the altitude of the treetop of the identified tree. The tree height calculation unit 716 calculates the height of the tree by taking the difference between the elevation of the ground surface on which the tree stands, calculated by the location identification unit 712, and the elevation of the tree top, calculated by the tree top height calculation unit 715. The diameter calculation unit 717 calculates the diameter of a tree from the distance map of the low-altitude observation aircraft 10 acquired by the data acquisition unit 711. For example, the diameter calculation unit 717 identifies the leftmost and rightmost pixels of the tree in the width direction perpendicular to the tree's axis direction in the distance map, and calculates the distance between the positions indicated by these pixels as the tree's diameter. The tree's diameter is one of the tree information items for the part of the tree below the trunk.

[0039] The species identification unit 718 identifies the type of tree based on the image captured by the imaging device 127 of the low-altitude observation aircraft 10. For example, the species identification unit 718 may identify the type of tree by inputting the image captured by the imaging device 127 of the low-altitude observation aircraft 10 into a trained model that takes an image as input and outputs the type of tree shown in the image. Alternatively, the species identification unit 718 may identify the type of tree by template matching using pre-prepared bark template images for each type of tree. Furthermore, if a color image can be obtained, such as when the rangefinder 121 is a stereo camera, the species identification unit 718 may identify the type of tree based on the image obtained by the rangefinder 121.

[0040] The defect identification unit 719 identifies the presence and type of defects in the trunk based on the image captured by the imaging device 127 of the low-altitude observation aircraft 10. Examples of defects include peeling bark and decay. For example, the defect identification unit 719 may identify the presence or absence of defects in a tree by inputting the image captured by the imaging device 127 of the low-altitude observation aircraft 10 into a trained model that takes an image as input and outputs whether or not there is peeling bark and decay in the tree shown in the image. Alternatively, the defect identification unit 719 may identify defects in a tree by template matching using template images prepared in advance for each type of defect. Information regarding defects in the trunk is one type of tree information below the trunk. If a color image can be obtained, such as when the rangefinder 121 is a stereo camera, the defect identification unit 719 may identify the presence or absence of defects in a tree based on the image obtained by the rangefinder 121.

[0041] The activity level calculation unit 720 calculates the activity level of trees based on the data cubes of the high-altitude observation instrument 30. For example, the activity level calculation unit 720 identifies the pixels in the data cubes that show the tree tops identified by the tree top altitude calculation unit 715, and calculates the tree activity level as the ratio of the brightness in the red region to the brightness in the infrared region of those pixels. The relative light intensity calculation unit 721 calculates the relative light intensity based on the illuminance measurements of the low-altitude observation aircraft 10 and the illuminance measurements of the high-altitude observation aircraft 30. The relative light intensity calculation unit 721 extracts the value corresponding to the time closest to when the low-altitude observation aircraft 10 measured the illuminance from the time series of the illuminance measurements of the high-altitude observation aircraft 30 and calculates the relative light intensity. Note that since the relative light intensity fluctuates depending on the altitude of the sun and the weather, the relative light intensity calculation unit 721 may absorb the fluctuations by taking the average of multiple measurements obtained at different times. Relative light intensity is one of the tree information values ​​for the part of the tree below the trunk.

[0042] The recording unit 722 records the date and time, type, height, diameter, activity level, defects, relative contrast with the surroundings, age, timber volume, and images captured by the imaging device 127 of the low-altitude observation instrument 10 in the database 751, in association with the ID acquired by the identification unit 714. The age can be calculated from the date the tree was planted and the current date and time, if that date is recorded as information at the time of planting. Alternatively, the age may be determined from the diameter or from image analysis of images captured by the imaging device 127. The timber volume may be calculated from the height, diameter, and type using a predetermined calculation formula. The recording unit 722 may also record the three-dimensional position of the tree on the ground surface in the database 751. In order to manage the growth history of the tree, the recording unit 722 adds data without overwriting past data.

[0043] The logging plan generation unit 723 generates a logging plan for thinning using forestry machinery 50 based on the condition of the trees recorded in the database 751. The logging plan generation unit 723 receives input from the user regarding the target area and logging rate, and determines which trees should be felled based on the height, activity level, health status, and relative contrast of the surrounding trees growing in the target area. For example, the logging plan generation unit 723 calculates a felling suitability score for each individual tree based on its activity level, health status, and relative contrast of the surrounding trees, and determines which trees should be felled in order from those with the highest felling suitability scores. A tree's felling suitability score increases when its activity level is below a predetermined threshold and there is a high probability of it dying while standing. The score also increases if there are defects in the trunk, as these defects are expected to reduce the tree's future value as timber. The score increase due to decay is greater than the score increase due to bark peeling. Furthermore, a lower relative brightness of the surrounding area results in a higher felling suitability score because the high density of trees in the canopy layer reduces sunlight exposure to trees in the sub-canopy and shrub layers. Additionally, a shorter and thinner tree results in a higher felling suitability score. Conversely, a younger tree results in a lower felling suitability score. In other words, even thin and short trees are not considered for felling if they are young. However, the method for determining which trees to fell is not limited to these criteria. In other embodiments, the logging plan generation unit 723 may receive a specification for the number of trees to be felled instead of the felling rate. Alternatively, the logging plan generation unit 723 may not receive a specification for the felling rate or the number of trees to be felled, and may select trees for felling if their felling suitability score exceeds a threshold.

[0044] The logging instruction unit 724 generates an instruction signal that includes the travel route and information indicating the identification and location of the trees to be felled, based on the logging plan generated by the logging plan generation unit 723, and transmits it to the forestry machine 50. When the logging instruction unit 724 receives notification of completion of felling along with the tree ID from the forestry machine 50, it rewrites the felling status of the tree corresponding to that ID in the database 751 to "felled".

[0045] Processing by the Forest Management Device 70 Figure 7 is a flowchart illustrating the tree information update process by the forest management device 70 according to the first embodiment. The operator controls the low-altitude observation device 10 and the high-altitude observation device 30 using the controller C1 to collect tree data within the target area of ​​forest F. The low-altitude observation device 10 collects data at the measurement timing when a measurement instruction signal is transmitted by the operator. The high-altitude observation device 30 collects data at regular intervals. When the operator's operation is complete, the low-altitude observation device 10 and the high-altitude observation device 30 transmit the collected data to the forest management device 70.

[0046] The data acquisition unit 711 acquires measurement data from the low-altitude observation aircraft 10 and the high-altitude observation aircraft 30 (step S1). The measurement data is accompanied by information indicating the measurement time. The forest management device 70 selects one measurement data from each of the multiple measurement timings collected by the low-altitude observation aircraft 10 (step S2), and uses the selected measurement data to perform the following processes from steps S3 to S18.

[0047] First, the position identification unit 712 identifies the three-dimensional position of the lower end of the tree from the position and attitude of the low-altitude observation aircraft 10 indicated by the measurement data selected in step S2, as well as from the distance map of the low-altitude observation aircraft 10 (step S3). Next, the fallen tree determination unit 713 identifies the axis direction of the tree from the distance map of the low-altitude observation aircraft 10 selected in step S2, and determines whether the angle between the axis direction and the horizontal plane is less than the fallen tree determination threshold (step S4). If the angle between the axis direction of the tree and the horizontal plane is less than the fallen tree determination threshold, the fallen tree determination unit 713 determines that the tree is fallen. If the tree is determined to be fallen (step S4: YES), the forest management device 70 skips monitoring the status of the tree and proceeds to process the next measurement timing in step S2. The fallen tree determination unit 713 may also record the location where the fallen tree is located in the database 751.

[0048] If the angle between the axis of the tree and the horizontal plane is greater than or equal to the fall detection threshold (Step S4: NO), the fall detection unit 713 determines that the tree is alive. Next, the identification unit 714 identifies an uncut tree from the database 751 that is closest to the latitude and longitude of the tree identified in Step S3, and determines whether the distance to that tree is less than a predetermined error threshold (Step S5). If the distance to the closest tree is less than the error threshold (Step S5: YES), the identification unit 714 determines that the tree shown on the distance map is that tree and obtains the ID of that tree (Step S6). On the other hand, if the distance to the closest tree is greater than or equal to the error threshold (Step S5: NO), the identification unit 714 determines that the tree shown on the distance map is a new tree, assigns a new ID (Step S7), and records the ID in the database 751 in association with the three-dimensional position identified in Step S3 (Step S8).

[0049] When the identification unit 714 obtains the individual ID in step S6 or step S7, the treetop altitude calculation unit 715 determines the altitude of the treetop of the individual identified in step S6 or step S7 from the distance map of the high-altitude observation device 30 obtained in step S1 (step S10).

[0050] The tree height calculation unit 716 calculates the height of the tree as the difference between the ground altitude calculated in step S3 and the tree crown altitude calculated in step S10 (step S11). The diameter calculation unit 717 calculates the diameter of the tree from the distance image of the low-altitude observation device 10 (step S12). The type identification unit 718 identifies the type of tree based on the image captured by the imaging device 127 (step S13). The defect identification unit 719 identifies the presence or absence of defects in the trunk and the type of defects based on the image captured by the imaging device 127 (step S14). The activity level calculation unit 720 identifies a pixel corresponding to the planar position identified by the position identification unit 712 from among the data cubes of the high-altitude observation device 30, and calculates the activity level of the tree as the ratio of the brightness in the red region to the brightness in the infrared region of that pixel (step S15). The relative light intensity calculation unit 721 extracts the value corresponding to the time closest to when the low-altitude observation aircraft 10 measured illuminance from the time series of illuminance measurements of the high-altitude observation aircraft 30, and calculates the relative light intensity using the illuminance of the low-altitude observation aircraft 10 and the illuminance of the high-altitude observation aircraft 30 (step S16).

[0051] The recording unit 722 records the obtained tree information, namely the type identified in step S13, the height calculated in step S11, the diameter calculated in step S12, the activity level calculated in step S15, the presence or absence of defects identified in step S14, and the relative illumination of the surroundings calculated in step S16, in the database 751, associating it with the ID and measurement time obtained in step S6 or step S7 (step S17).

[0052] By performing the above procedure for each measurement timing of the low-altitude observation aircraft 10, the information on individual trees in the database 751 can be updated to the latest state. Note that the collection of tree information may be performed at times unrelated to thinning.

[0053] Figure 8 is a flowchart illustrating the logging plan generation process by the forest management device 70 according to the first embodiment. The operator accesses the forest management device 70 at the time of thinning and inputs the target area for thinning and the logging rate. The logging rate may be automatically determined from the average value of relative light intensity recorded in the database 751, rather than being input by the operator. The logging plan generation unit 723 receives input from the user regarding the target area and the logging rate (step S31). The logging plan generation unit 723 determines the number of trees to be felled based on the number of unfelled trees within the target area recorded in the database 751 and the input logging rate (step S32). For each unfelled individual within the target area recorded in the database 751, the logging plan generation unit 723 calculates a logging suitability score based on the latest status of that individual (step S33). The logging plan generation unit 723 generates a logging plan by selecting the individuals to be felled based on the number of trees determined in step S32, in order from those with the highest logging suitability scores (step S34).

[0054] The logging instruction unit 724 determines the travel route of the forestry machine 50 based on the logging plan generated by the logging plan generation unit 723 (step S35). The logging instruction unit 724 searches for the shortest route that passes through all the trees that have been determined to be felled. The logging instruction unit 724 generates an instruction signal including the determined travel route and the IDs and locations of the trees to be felled, and transmits it to the forestry machine 50 (step S36). As a result, the forestry machine 50 autonomously travels along the travel route and fells the trees to be felled. The control device 54 of the forestry machine 50 transmits a felling notification including the ID of the felled tree to the forest management device 70 when the tree is felled. When the logging instruction unit 724 receives the felling notification from the forestry machine 50 (step S37), it rewrites the felling status of the tree corresponding to that ID in the database 751 to felled (step S38).

[0055] As a result, the forest management device 70 can instruct the forestry machinery 50 to perform logging based on tree information collected by the low-altitude observation device 10 and the high-altitude observation device 30, and record the logging results in the database 751.

[0056] Action / Effect As described above, according to the forest management system 1 of the first embodiment, the location of trees is identified based on images taken by a low-altitude observation aircraft 10 moving through the forest at an altitude lower than the forest canopy, and the position at the time of acquisition, and individual trees are identified based on their locations. As a result, the forest management system 1 can measure and manage trees throughout the entire forest, including trees whose treetops are lower than the forest canopy, which cannot be measured by the high-altitude observation aircraft 30. Furthermore, the forest management system 1 records information on the part of each individual tree below the canopy in the database 751, based on images taken by the low-altitude observation aircraft 10, and associates it with the ID of that individual tree. As a result, the forest management system 1 can collect tree information on the part of the tree below the canopy that is not visible in images taken from above.

[0057] Furthermore, the forest management system 1 according to the first embodiment can calculate the ground altitude of trees that cannot be measured from images taken from above, based on images taken by the low-altitude observation aircraft 10. Based on the ground altitude and the tree crown altitude obtained from images taken by the high-altitude observation aircraft 30, the forest management system 1 can accurately determine the height of the trees. In other embodiments, however, the forest management system 1 may not calculate the height of the trees, but may record the ground altitude and tree crown altitude in the database 751. Also, the forest management system 1 according to other embodiments may not record information regarding tree height in the database 751. In other words, the forest management system 1 according to other embodiments may record data measured only by the low-altitude observation aircraft 10 in the database 751.

[0058] Furthermore, the forest management system 1 according to the first embodiment calculates relative light intensity based on the illuminance measured by the low-altitude observation device 10 and the illuminance measured by the high-altitude observation device 30, and records it in the database 751 in association with individual trees. Relative light intensity affects the growth of the shrub layer and forest floor of the forest. Therefore, by recording such information in the database 751, the forest management system 1 can appropriately manage the forest F. Although the forest management system 1 according to the first embodiment calculates relative light intensity, it is not limited to this, and in other embodiments, the forest management system 1 may record the illuminance at an altitude lower than the forest canopy, i.e., the illuminance measured by the low-altitude observation device 10, in the database 751. In this case, the high-altitude observation device 30 does not need to be equipped with an illuminance sensor 315.

[0059] <Second Embodiment> In the first embodiment, the low-altitude observation aircraft 10 and the high-altitude observation aircraft 30 are remotely controlled by an operator. In contrast, in the second embodiment, the low-altitude observation aircraft 10 and the high-altitude observation aircraft 30 operate autonomously according to instructions from the forest management device 70.

[0060] Figure 9 is a schematic block diagram showing the configuration of the forest management device 70 according to the second embodiment. The forest management device 70 according to the second embodiment further includes a measurement indicator unit 725 in addition to the configuration of the first embodiment. The measurement instruction unit 725 generates an observation instruction signal instructing the observation of trees present within the target area of ​​forest F and transmits it to the low-altitude observation device 10 and the high-altitude observation device 30. The observation instruction signal includes information indicating the movement route. For example, the measurement instruction unit 725 generates a movement route such that the trajectory of the measurement range of the distance measuring device 121 accompanying the movement of the low-altitude observation device 10 covers the target area. If the route to be traveled by the forestry machinery 50 is predetermined, the measurement instruction unit 725 may transmit an observation instruction signal that uses the route to be traveled by the forestry machinery 50 as the movement route. Furthermore, if the control device 126 of the low-altitude observation device 10 autonomously determines whether or not the target area has been covered by its movement, the measurement instruction unit 725 may transmit an observation instruction signal that includes information indicating the target area instead of the movement route.

[0061] The control device 126 of the low-altitude observation aircraft 10 moves the low-altitude observation aircraft 10 along the movement route indicated by the received observation instruction signal. For example, the control device 126 may generate an environmental map by SLAM (Simultaneous Localization and Mapping) processing based on the distance map captured by the ranging device 121 and the position data measured by the positioning device 122, and control the moving device 11 while correcting the movement route. While moving based on the observation instruction signal, the control device 126 determines whether or not trees are visible on the distance map, and if it determines that trees are visible, it collects measurement data. For example, the control device 126 can determine whether or not trees are visible using three-dimensional pattern matching or a trained object detection model.

[0062] The control device 317 of the high-altitude observation aircraft 30 causes the high-altitude observation aircraft 30 to fly at a predetermined altitude above the canopy along the movement route indicated by the received observation instruction signal. The control device 317 may move the high-altitude observation aircraft 30 in synchronization with the low-altitude observation aircraft 10, or it may move the high-altitude observation aircraft 30 independently of the low-altitude observation aircraft 10.

[0063] The control devices 126 of the low-altitude observation aircraft 10 and 317 of the high-altitude observation aircraft 30 may control their movement based on instruction signals received from the operator if an interrupt operation is received from the operator during autonomous operation. Subsequently, when instruction signals from the operator cease, the control devices 126 of the low-altitude observation aircraft 10 and 317 of the high-altitude observation aircraft 30 switch to autonomous operation along the movement route. The control devices 126 of the low-altitude observation aircraft 10 and 317 of the high-altitude observation aircraft 30 transmit the collected measurement data to the forest management device 70 once movement along the travel route is complete. This allows the forest management device 70 to record tree information of trees standing near its travel route in the database 751.

[0064] <Other Embodiments> Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to that described above, and various design changes are possible. In other embodiments, the order of the above-described processes may be changed as appropriate. Also, some processes may be executed in parallel.

[0065] In the forest management system 1 according to the above embodiment, the low-altitude observation device 10 and the high-altitude observation device 30 transmit the measurement data to the forest management device 70 without processing it, and the forest management device 70 calculates tree information such as tree type, ground surface altitude, diameter, activity level, and defects from the measurement data, but is not limited to this. For example, in the forest management system 1 according to another embodiment, the control device 126 of the low-altitude observation device 10 or the control device 317 of the high-altitude observation device 30 may calculate tree information based on the measurement data, and the forest management device 70 may receive the calculated tree information. In other words, the forest management device 70 may be composed of a single computer, or the configuration of the forest management device 70 may be divided and arranged among multiple computers, and the multiple computers may cooperate with each other to function as the forest management device 70. In this case, some of the computers constituting the forest management device 70 may be mounted inside the low-altitude observation device 10 or the high-altitude observation device 30, and the other computers may be provided externally.

[0066] The forest management system 1 according to the above embodiment generates a logging plan based on information recorded in the database 751 and transmits instructions to the autonomously operated forestry machine 50, but is not limited to this. For example, the forest management system 1 according to another embodiment may not generate a logging plan and may only perform individual tree management. Also, for example, in another embodiment, the forestry machine 50 may not operate autonomously but may be directly operated by an operator or remotely operated. In this case, the forest management device 70 outputs an instruction signal that instructs the operator to perform logging according to the logging plan. This instruction signal may be a signal to display the logging plan on a monitor in the driver's cab of the forestry machine 50, or a signal to display the logging plan on a portable terminal held by the operator.

[0067] The forest management system 1 according to the above embodiment determines the altitude of the ground on which trees stand based on measurement data from the low-altitude observation aircraft 10, and calculates the height of the trees based on this, but is not limited to this. For example, the altitude of the ground may be read from three-dimensional map data stored in an external database. The forest management system 1 according to the above embodiment also determines the illuminance of the upper atmosphere using the illuminance sensor 315 equipped on the high-altitude observation aircraft 30, and calculates the relative intensity based on this, but is not limited to this. For example, the illuminance of the upper atmosphere may be read from meteorological data stored in an external database.

[0068] In the forest management system 1 according to the above embodiment, the low-altitude observation device 10 is equipped with a ranging device 121 capable of acquiring distance maps in order to obtain state variables related to size, such as height and diameter, as state variables of trees. On the other hand, in other embodiments, when calculating only state variables unrelated to size, such as the type of tree and the presence or absence of defects, the ranging device 121 that generates distance maps does not need to be provided. In this case, the low-altitude observation device 10 may measure the distance to the trees by being equipped with a laser rangefinder or the like separately from the imaging device 127.

[0069] (Note 1) A data acquisition unit obtains the low-altitude distance map generated by the ranging device and the position of the low-altitude observation device from the low-altitude observation device, which is equipped with a ranging device that generates a distance map and a positioning device that measures its own position, as the low-altitude observation device moves through the area of ​​the forest near the ground where there are no branches or leaves. A position identification unit that identifies the location of the tree based on the distance from the low-altitude observation aircraft to the tree, which is determined based on the low-altitude distance map, and the position of the low-altitude observation aircraft. An identification unit that acquires identification information to identify an individual tree based on the position of the tree, A recording unit records low-altitude tree information, which is tree information of the part of the individual tree that is lower than the branches and leaves, measured based on the low-altitude distance map, in a database in association with the identification information. A forest management system equipped with [features / equipment].

[0070] (Note 2) The system includes an altitude calculation unit that calculates the altitude of the ground surface on which the trees stand, which is the low-altitude tree information, based on the low-altitude distance map and the three-dimensional position of the low-altitude observation device in the global coordinate system. The forest management system described in Appendix 1.

[0071] (Note 3) The recording unit records high-altitude tree information, which is tree information of the individual measured from the portion of the high-altitude imaging data captured from above the forest in which the individual is visible, in the database in association with the identification information of the individual. The forest management system described in Appendix 1 or Appendix 2.

[0072] (Note 4) The system includes a height calculation unit that calculates the height of the individual based on the height of the treetop of the individual, measured from the portion of a high-altitude distance map taken from an altitude higher than the forest canopy in which the individual is visible, and the height of the ground on which the individual is standing. The recording unit records the height of the individual in the database in association with the identification information of the individual. A forest management system as described in any of the appendices 1 through 3.

[0073] (Note 5) The height calculation unit identifies the height of the tree head of the individual, which is the tree head whose planar position is closest to the planar position of the individual related to the identification information, from among the multiple tree heads identified from the high-altitude distance map measured from above the forest. The forest management system described in Appendix 4.

[0074] (Note 6) The aforementioned low-altitude observation aircraft is equipped with an illuminance sensor, The data acquisition unit acquires the illuminance data measured by the illuminance sensor, The recording unit records the values ​​related to the illuminance data in the database, associating them with the identification information of the trees. A forest management system as described in any of the appendices 1 through 5.

[0075] (Note 7) The database stores identification information for identifying individual trees, the location of the individual tree, and low-altitude tree information for the individual tree, in association with each other. The identification unit assigns new identification information to the individual if the identification information corresponding to the identified location is not recorded in the database. A forest management system as described in any of the appendices 1 through 6.

[0076] (Note 8) The low-altitude observation aircraft moves through the forest along the route used by forestry machinery for felling trees. The recording unit records low-altitude tree information of trees standing near the driving route in the database. A forest management system as described in any of the appendices 1 through 7.

[0077] (Note 9) A logging plan generation unit generates a logging plan that indicates which trees should be felled by forestry machinery based on the information recorded in the aforementioned database, A logging instruction unit transmits an instruction signal to the forestry machine to instruct logging to be carried out according to the logging plan generated above. A forest management system described in any of the appendices 1 to 8, comprising the features specified in appendices 1 to 8.

[0078] (Note 10) The system includes a fallen tree determination unit that determines whether a tree is fallen or alive based on the angle of the tree relative to the horizontal as captured in the low-altitude imaging data. The identification unit acquires identification information of the tree when it is determined that the tree is a living tree. A forest management system as described in any of the appendices 1 through 9. [Explanation of Symbols]

[0079] 1…Forest Management System 10…Low Altitude Observation Vehicle 11…Tracking System 12…Aircraft Body 121…Rangefinder 122…Positioning System 123…Attitude Measurement System 124…Illuminance Sensor 125…Battery 126…Control System 127…Imaging System 30…High Altitude Observation Vehicle 31…Aircraft Body 311…Rangefinder 312…Multispectral Camera 313…Positioning System 314…Attitude Measurement System 315…Illuminance Sensor 316…Battery 317…Control System 32…Propeller 50…Forestry Machinery 51…Vehicle Body 511…Positioning System 52…Tracking System 53…Work Machinery 531…Boom 532…Arm 533…Head 5331…Grapple 5332…Circular Saw 534…Arm Cylinder 535…Head Cylinder 54…Control System 70…Forest Management System 71…Processor 751…Database 711…Data acquisition unit 712…Location identification unit 713…Fallen tree detection unit 714…Identification unit 715…Tree cap height calculation unit 716…Tree height calculation unit 717…Diameter calculation unit 718…Type identification unit 719…Defect identification unit 720…Activity level calculation unit 721…Relative light intensity calculation unit 722…Recording unit 723…Logging plan generation unit 724…Logging instruction unit 725…Measurement instruction unit 73…Main memory 75…Storage 77…Interface F…Forest N…Communication network

Claims

1. A data acquisition unit obtains the low-altitude distance map generated by a distance measuring device and the position of a low-altitude observation device from a low-altitude observation device equipped with a distance measuring device that moves through the area of ​​the forest near the ground where there are no branches or leaves and generates a distance map, and a positioning device that measures its own position. A position identification unit that identifies the location of the tree based on the distance from the low-altitude observation aircraft to the tree, which is determined based on the low-altitude distance map, and the position of the low-altitude observation aircraft. A database that stores, for each individual tree, an ID that identifies the individual tree and the location of the individual tree in association with each individual tree, and an identification unit that obtains the ID of the individual tree based on the identified location of the tree. A recording unit records low-altitude tree information, which is tree information of the part of the individual that is lower than the branches and leaves, measured based on the low-altitude distance map, in the database in association with the ID, and high-altitude tree information, which is tree information of the individual that is measured from the part of the high-altitude imaging data taken from above the forest that shows the individual, in the database in association with the ID of the individual. A forest management system equipped with [features / equipment].

2. The system includes an altitude calculation unit that calculates the altitude of the ground surface on which the trees stand, which is the low-altitude tree information, based on the low-altitude distance map and the three-dimensional position of the low-altitude observation device in the global coordinate system. The forest management system according to claim 1.

3. The recording unit records high-altitude tree information, which is tree information of the individual measured from the portion of the high-altitude imaging data captured from above the forest in which the individual is visible, in the database in association with the ID of the individual. A forest management system according to claim 1 or claim 2.

4. The system includes a height calculation unit that calculates the height of the individual based on the height of the treetop of the individual, measured from the portion of a high-altitude distance map taken from an altitude higher than the forest canopy in which the individual is visible, and the height of the ground on which the individual is standing. The recording unit records the height of the individual in the database in association with the ID of the individual. A forest management system according to claim 1 or claim 2.

5. The height calculation unit identifies the height of the tree head of the individual, which is the tree head whose planar position is closest to the planar position of the individual corresponding to the ID, from among a plurality of tree heads identified from a high-altitude distance map measured from above the forest. The forest management system according to claim 4.

6. The aforementioned low-altitude observation aircraft is equipped with an illuminance sensor, The data acquisition unit acquires the illuminance data measured by the illuminance sensor, The recording unit records the values ​​related to the illuminance data in the database, associating them with the ID of the tree. A forest management system according to claim 1 or claim 2.

7. The database stores an ID that identifies an individual tree, the location of the individual tree, and low-altitude tree information of the individual tree, in association with each other. The identification unit assigns a new ID to the individual if an ID corresponding to the identified location is not recorded in the database. A forest management system according to claim 1 or claim 2.

8. The low-altitude observation aircraft moves through the forest along the route used by forestry machinery for felling trees. The recording unit records low-altitude tree information of trees standing near the driving route in the database. A forest management system according to claim 1 or claim 2.

9. A logging plan generation unit generates a logging plan that indicates which trees should be felled by forestry machinery based on the information recorded in the aforementioned database, A logging instruction unit transmits an instruction signal to the forestry machine to instruct logging to be carried out according to the logging plan generated above. A forest management system according to claim 1 or claim 2, comprising:

10. The system includes a fallen tree determination unit that determines whether a tree is fallen or alive based on the angle of the tree relative to the horizontal as seen in the low-altitude imaging data captured by the low-altitude observation device, The identification unit obtains the ID of the tree when it is determined that the tree is a living tree. A forest management system according to claim 1 or claim 2.

11. A low-altitude observation aircraft moves in a forest area near the ground where there are no branches or leaves, and is equipped with a ranging device that generates a distance map and a positioning device that measures the position of the low-altitude observation aircraft. The steps include obtaining the low-altitude distance map generated by the ranging device and the position of the low-altitude observation aircraft from the low-altitude observation aircraft, A step of determining the location of the tree based on the distance from the low-altitude observation aircraft to the tree, which is determined based on the low-altitude distance map, and the position of the low-altitude observation aircraft. A database that stores, for each individual tree, an ID that identifies the individual and the location of the individual, and a step of obtaining the ID of the individual tree based on the location of the identified tree. The steps include recording low-altitude tree information, which is tree information of the part of the individual that is lower than the branches and leaves, measured based on the low-altitude distance map, in the database in association with the ID, and recording high-altitude tree information, which is tree information of the individual that is measured from the part of the high-altitude imaging data taken from above the forest that shows the individual, in the database in association with the ID of the individual. A forest management method that includes the following features.

Images