JP7000175B2 - Image generator for tree diagnosis and image generation method for tree diagnosis - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act September 27, 2017 IEICE Technical Report Vol. 117 No. 222 SANE2017-43-SANE2017-62 Announced at Space and Navigation Electronics October 5, 2017 Announced at the Society of Exploration Geotechnical Science Space and Navigation Electronics Study Group (SANE) Underground Electromagnetic Measurement Workshop November 1, 2017 32nd Announced at the Nippon Road Conference October 31, 2017 Announced in the 32nd Nippon Road Conference Proceedings published by the Nippon Road Association November 10, 2017 Society of Exploration Geotechnical Society 137th (2017) Announced at the Academic Lecture on November 8, 2017 Presented at the 137th (Autumn 2017) Academic Lecture Proceedings published by the Society of Exploration Geotechnical Society of Japan

The present invention relates to a technique for generating an image for tree diagnosis.

Conventionally, a method called a resist graph has been known as a method for diagnosing decay inside a tree trunk. The resist graph is made by drilling an elongated hole in the trunk with an electric drill and recording the resistance value at the time of drilling. By repeating this work from multiple directions on the trunk, the decay area is estimated. Since this method involves the destructive work of perforating the trunk, there is a possibility that the perforated part will be damaged and rotting fungi will invade from there, causing the trunk to rot. Therefore, it is considered difficult to apply this method to trees that need to be preserved, such as famous trees.

As a non-destructive method for estimating decay, there is a method using acoustic tomography. In this method, about a dozen microphones (sensors) are driven into the trunk from the bark, then sound waves are transmitted into the trunk, the travel time of the sound waves is measured, and the speed of the P wave on the trunk cross section. Reconstruct the distribution. In this method, since the sensor is installed by driving screws, nails, etc. into the bark to the lower surface of the cork layer, it is not completely non-destructive and is accompanied by slight scratches. Patent Document 1 below proposes a method of attaching a sensor to the bark in a non-destructive manner using clay, but this method may deteriorate the acquisition sensitivity (S / N ratio) of sound waves, which are elastic waves. It is considered expensive.

In addition to the method using sound waves, there is a measurement method using γ-ray transmittance. In this method, the permeation dose is measured using a radiation source arranged across the trunk and a radiation detector, and the state of decay is estimated. However, since this method uses radiation, there is a problem that the equipment cost and the work cost tend to be high.

Japanese Unexamined Patent Publication No. 2006-53045

The present invention has been made in view of the above circumstances. A main object of the present invention is to provide a technique for efficiently visualizing the internal state of a tree in a non-destructive manner.

The present invention can be expressed as the invention described in the following items.

(Item 1)
It is a device for imaging the internal state of the trunk in a tree, and is equipped with a radar scan unit, a stem shape measurement unit, and a migration processing unit.
The radar scanning unit receives the reflected wave of the radio wave transmitted toward the inside of the trunk and scans along the outer circumference of the trunk to acquire scan data about the internal state of the trunk. It is configured to
The trunk shape measuring unit is configured to acquire the cross-sectional shape of the trunk.
The migration processing unit is an image generation device for tree diagnosis, which is configured to generate a cross-sectional image of the trunk by performing migration processing on the scan data using the cross-sectional shape.

(Item 2)
The image generation device for tree diagnosis according to item 1, wherein the radar scanning unit includes a transmitting unit that transmits radio waves toward the inside of the trunk and a receiving unit that receives reflected waves of the radio waves.

(Item 3)
Furthermore, it is equipped with a relative permittivity measuring unit.
The relative permittivity measuring unit is configured to measure the relative permittivity inside the trunk by using the propagation speed of radio waves inside the trunk.
The image generation device for tree diagnosis according to item 1 or 2, wherein the migration processing unit performs the migration processing using the relative permittivity measured by the relative permittivity measuring unit.

(Item 4)
It also has an output section.
The image generation device for tree diagnosis according to any one of items 1 to 3, wherein the output unit is configured to output the cross-sectional image generated by the migration processing unit.

(Item 5)
It is a method for imaging the internal state of the trunk in a tree.
A scan of the internal state of the trunk by receiving the reflected wave of the radio wave transmitted toward the inside of the trunk while scanning both the radiation position and the reception position of the radio wave along the outer periphery of the trunk. Steps to get the data and
The step of acquiring the cross-sectional shape of the trunk and
A method for generating an image for tree diagnosis, which comprises a step of generating a cross-sectional image of the trunk by performing a migration process on the scan data using the cross-sectional shape.

According to the present invention, it becomes possible to efficiently visualize the internal state of a tree in a non-destructive manner.

It is a block diagram for showing the schematic structure of the tree diagnostic apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows the schematic structure of the radar scan part in the apparatus of FIG. It is explanatory drawing which shows the schematic structure of the trunk shape measuring part in the apparatus of FIG. It is a flowchart for demonstrating the procedure of the image generation method using the apparatus of FIG. It is an image showing the scan data obtained by the radar scan unit. The horizontal axis is the position in the circumferential direction of the trunk (that is, the moving distance of the radar scan unit), the vertical axis is the reception time of the reflected wave, and the density is the reflected wave. Amplitude (black is larger negative amplitude, white is larger positive amplitude). An image showing the same scan data as in FIG. 5A, the horizontal axis is the position in the circumferential direction of the trunk, the vertical axis is the reception time of the reflected wave, and the radar waveform (reception) corresponds to the position where the data was acquired. The time waveform of the reflected wave) is displayed. It is data showing the trunk shape measured from one direction, and the horizontal axis is the X coordinate in the horizontal plane and the vertical axis is the Y coordinate. It is data showing the trunk shape measured from another direction, and the horizontal axis is the X coordinate in the horizontal plane and the vertical axis is the Y coordinate. It is data showing the cross-sectional shape of the trunk obtained by synthesizing the measurement data for two times, and the horizontal axis is the X coordinate in the horizontal plane and the vertical axis is the Y coordinate. It is an image which shows the cross-sectional image of the trunk obtained by the migration process.

Hereinafter, an image generation device for tree diagnosis (hereinafter, may be abbreviated as “image generation device” or simply “device”) according to an embodiment of the present invention will be described with reference to the accompanying drawings.

(Structure of this embodiment)
The apparatus of this embodiment includes a radar scanning unit 1, a stem shape measuring unit 2, and a migration processing unit 3 as basic elements (see FIG. 1). Further, this device includes a relative permittivity measuring unit 4 and an output unit 5 as additional elements.

(Radar scan section)
The radar scanning unit 1 receives the reflected wave of the radio wave transmitted toward the inside of the trunk 10 in the tree, and scans along the outer circumference of the trunk 10 to scan data about the internal state of the trunk 10. It is configured to acquire.

More specifically, the radar scanning unit 1 includes a transmitting unit 11 that transmits radio waves toward the inside of the trunk 10 and a receiving unit 12 that receives the reflected waves of the radio waves (see FIG. 2). The transmitting unit 11 and the receiving unit 12 of the radar scanning unit 1 in this example can be integrally moved (that is, scanned) in the outer peripheral direction of the trunk 10 (that is, in the direction of the arrow in FIG. 2).

(Stem shape measuring unit)
The trunk shape measuring unit 2 is configured to acquire the cross-sectional shape of the trunk 10. More specifically, the trunk shape measuring unit 2 of the present embodiment includes a distance measuring unit 21 and a reflecting unit 22 (see FIG. 3). The distance measuring unit 21 has a configuration in which the distance to the reflection position can be accurately measured by using the reflection of the laser beam, and specifically, a so-called total station (TS) is used. The reflecting unit 22 has a configuration capable of reflecting the laser beam from the distance measuring unit 21, and specifically, a so-called 360 ° prism is used.

(Migration processing unit)
The migration processing unit 3 is configured to generate a cross-sectional image of the trunk 10 by performing migration processing on scan data using the cross-sectional shape of the trunk 10. More specifically, the migration processing unit 3 is configured to perform migration processing using the relative permittivity measured by the relative permittivity measuring unit 4. More specific contents of the migration process will be described later.

(Relative permittivity measuring unit)
The relative permittivity measuring unit 4 is configured to measure the relative permittivity inside the trunk 10 by using the propagation speed of the radio wave inside the trunk 10. Specifically, the relative permittivity measuring unit 4 of this example measures the propagation time of radio waves using a transmitting antenna and a receiving antenna (not shown) arranged opposite to each other with the trunk 10 interposed therebetween. .. The propagation velocity of radio waves can be obtained from the relationship between the propagation time and the propagation distance, and the relative permittivity can be calculated from the propagation velocity.

(Output section)
The output unit 5 is configured to output the cross-sectional image generated by the migration processing unit 3. The output unit 5 is, for example, a display for presenting an image to a user, but is not limited thereto, and for example, transfers an image to the outside via various memories for recording the image or a network. It may be an interface for.

(Image generation method in this embodiment)
Next, the image generation method in the present embodiment will be described with reference to FIG. 4.

(Step SA-1 in FIG. 4)
First, in a state where the radar scanning unit 1 is pressed against the trunk 10 of the tree (see FIG. 2), radio waves are transmitted from the transmitting unit 11 toward the inside of the trunk 10. The reflected wave of the transmitted radio wave is received by the receiving unit 12. This transmission / reception operation is performed while scanning both the transmission position and the reception position of the radio wave along the outer circumference of the trunk 10. The reception intensity and reception time (time from transmission to reception) of the radio wave are recorded corresponding to the moving distance of the reception unit 12 (that is, the radar scan unit 1) in the outer peripheral direction of the trunk 10. In this embodiment, it is possible to acquire scan data about the internal state of the trunk 10.

An example of the obtained scan data is shown in FIG. 5A. In this figure, the amplitude of the received radio wave signal is described in black and white shades, and black indicates a large negative amplitude, and white indicates a large positive amplitude. FIG. 5B shows the same data as in FIG. 5A as a time waveform of the received wave at the reception position, and shows the negative amplitude filled with black (such a data display method is generally a wiggle trace). ).

Here, the reception time of the reflected wave can be converted into a depth by assuming the propagation speed of the radio wave. The propagation velocity v of the radio wave in the tree can be expressed by the following equation (1).

here,
c = 3 × ¹⁰⁸ [m / s]: Propagation speed of radio waves in free space ε _r : Relative permittivity inside the trunk. The measurement of the relative permittivity will be described later.

(Step SA-2 in FIG. 4)
The relative permittivity inside the trunk is measured by the relative permittivity measuring unit 4 in parallel with or before and after step SA-1. Specifically, the radio wave transmitting unit and the radio wave receiving unit are positioned so as to face each other with the trunk 10 interposed therebetween, and the radio wave is transmitted and received, and the propagation time of the radio wave is measured. The propagation time of radio waves can be measured by an appropriate method such as detection of a time waveform such as a pulsed waveform. From the obtained propagation time and the known propagation distance, the actual propagation velocity of the radio wave is measured. Using the measured radio wave velocity, the relative permittivity ε _r can be calculated from the above equation (1). Here, the diameter of the trunk 10 can be used as the propagation distance of the radio wave. The diameter of the trunk 10 may be directly measured using a jig, or the measurement result by the trunk shape measuring unit 2 described later may be used.

(Step SA-3 in FIG. 4)
Then, the trunk shape measuring unit 2 acquires the cross-sectional shape of the trunk 10. Specifically, the reflecting unit 22 is moved (scanned) along the outer circumference of the trunk, and the position (position on the horizontal plane) of the reflecting unit 22 is measured by the ranging unit 21. However, when the reflective portion 22 is hidden behind the trunk 10, the position of the ranging unit 21 is appropriately moved, and the position of the reflective portion 22 is measured from the opposite side (see the two-dot chain line in FIG. 3). Here, the distance measuring unit 21 also measures the positions of a plurality of reference points installed on the ground. FIG. 6A shows the cross-sectional shape of the trunk 10 measured from the distance measuring unit 21 installed at a certain position. The shaded area of the trunk 10 has not been measured. FIG. 6B shows the cross-sectional shape of the trunk 10 measured from another position (position on the opposite side).

Next, the trunk shape measuring unit 2 performs coordinate conversion so that the positions of the reference points have the same coordinates, and then synthesizes the measurement data for two times, that is, the data of FIG. 6A and the data of FIG. 6B. As a result, shape data (cross-sectional shape) for one round of the trunk 10 can be obtained. The obtained cross-sectional shape is shown in FIG. Here, when there is a distance from the surface of the trunk 10 to the reflecting portion 22, it is preferable to obtain a cross-sectional shape in which the distance is corrected. In the present embodiment, the position of the trunk 10 measured by the trunk shape measuring unit 2 is substantially the same as the position measured by the radar scanning unit 1.

(Step SA-4 in FIG. 4)
Then, using the obtained cross-sectional shape, migration processing (that is, synthetic aperture radar processing) is performed on the scan data shown in FIG. 5A or FIG. 5B. Thereby, a cross-sectional image of the trunk 10 can be generated. In the migration process, the relative permittivity measured by the relative permittivity measuring unit 4 is used. In this embodiment, it is assumed that the relative permittivity inside the trunk 10 is uniform. For the reflected wave of the radio wave generated inside the trunk 10, the round-trip time to the reflected position (distance when the above-mentioned propagation speed is assumed) is known, but the direction in which the reflected wave arrives is not known. In the migration process itself, the waveform amplitude is given to all the positions where the radio waves may be reflected. By repeating this process for all the waveforms acquired when the transmitting unit and the receiving unit of the radio wave move around the outer circumference of the trunk 10, the amplitude is amplified at the true reflection position and the amplitude is reduced at the non-reflection position. Since such a migration process has been known conventionally, further detailed description thereof will be omitted.

FIG. 8 shows an example of a cross-sectional image obtained by the migration process. The numbers on the outer circumference of the cross-sectional image in FIG. 8 indicate the distance (meters) in the outer peripheral direction of the trunk 10. The higher the brightness in the figure, the higher the positive reflection intensity, and the lower the brightness, the higher the negative reflection intensity. According to FIG. 8, it is observed that a portion having strong reflection exists in an annular shape inside the trunk, and it can be estimated that there is an annular decay portion inside the trunk.

(Step SA-5 in FIG. 4)
Then, the output unit 5 outputs the obtained cross-sectional image. For example, the output unit 5 can print a cross-sectional image or present the cross-sectional image to the user as visual information.

It should be noted that the description of the embodiment is merely an example, and does not show the configuration essential to the present invention. The configuration of each part is not limited to the above as long as the gist of the present invention can be achieved.

For example, in the above-described embodiment, the migration process is performed using the relative permittivity measured by the relative permittivity measuring unit, but the relative permittivity is determined in advance by some method or experimentally determined in advance. Permittivity may be used. For example, when diagnosing a large number of trees rapidly, the migration process can be performed using a relative permittivity that is generally valid to some extent.

1 Radar scan unit 11 Transmitter unit 12 Receiver unit 2 Trunk shape measurement unit 21 Distance measurement unit (total station)
22 Reflector (360 ° prism)
23 Reference point 3 Migration processing unit 4 Relative permittivity measuring unit 10 Trunk

Claims (5)

It is a device for imaging the internal state of the trunk in a tree, and is equipped with a radar scan unit, a stem shape measurement unit, and a migration processing unit.
The radar scanning unit receives the reflected wave of the radio wave transmitted toward the inside of the trunk and scans along the outer circumference of the trunk to acquire scan data about the internal state of the trunk. It is configured to
Moreover, the radar scanning unit includes a transmitting unit that transmits the radio wave toward the inside of the trunk and a receiving unit that receives the reflected wave of the radio wave.
The transmitting unit and the receiving unit are configured to be able to move integrally in the outer peripheral direction of the trunk and scan the outer peripheral surface of the trunk.
In the scan data, the reception intensity of the reflected wave and the reception time, which is the time from transmission to reception, are recorded corresponding to the moving distance of the reception unit in the outer peripheral direction of the trunk.
The trunk shape measuring unit is configured to acquire the cross-sectional shape of the trunk.
The migration processing unit is an image generation device for tree diagnosis, which is configured to generate a cross-sectional image of the trunk by performing migration processing on the scan data using the cross-sectional shape. The trunk shape measuring unit includes a distance measuring unit that can measure the distance to the reflection position by using the reflection of the laser beam, and a reflecting unit that can reflect the laser light from the ranging unit.
Further, the trunk shape measuring unit scans the reflecting portion along the outer periphery of the trunk, and measures the position of the reflecting portion by the ranging unit to obtain a first cross-sectional shape and the reflecting portion. The second cross-sectional shape obtained by appropriately moving the position of the distance measuring portion and then measuring the position of the reflecting portion from the opposite side and installed on the ground in the case where is hidden behind the trunk. Using the reference point information obtained by measuring the positions of a plurality of reference points by the distance measuring unit, the first cross-sectional shape and the second cross-sectional shape are combined, and the cross-sectional shape of one circumference of the trunk is combined. The image generation device for tree diagnosis according to claim 1, which is configured to obtain a shape . Furthermore, it is equipped with a relative permittivity measuring unit.
The relative permittivity measuring unit is configured to measure the relative permittivity inside the trunk by using the propagation speed of radio waves inside the trunk.
The image generation device for tree diagnosis according to claim 1 or 2, wherein the migration processing unit performs the migration processing using the relative permittivity measured by the relative permittivity measuring unit. It also has an output section.
The image generation device for tree diagnosis according to any one of claims 1 to 3, wherein the output unit is configured to output the cross-sectional image generated by the migration processing unit. It is a method for imaging the internal state of the trunk in a tree.
The reflected wave of the radio wave transmitted from the transmitting unit toward the inside of the trunk is scanned together with the radiation position and the receiving position of the radio wave along the outer periphery of the trunk by the receiving unit that moves integrally with the transmitting unit. While receiving, the step of acquiring scan data about the internal state of the trunk, and here, the scan data has the reception intensity of the reflected wave and the reception time which is the time from transmission to reception. , It was recorded corresponding to the moving distance of the receiving unit in the outer peripheral direction of the trunk.
The step of acquiring the cross-sectional shape of the trunk and
A method for generating an image for tree diagnosis, which comprises a step of generating a cross-sectional image of the trunk by performing a migration process on the scan data using the cross-sectional shape.

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