Survey device

Abstract

To provide a survey device capable of acquiring information on a pavement multilayer structure layer in which a buried pipe is installed.SOLUTION: A survey device using an underground radar comprises: a reflected signal processing unit 41 that generates two-dimensional image data representing a cross section of a pavement multilayer structure layer on the basis of reflected signals of an emitted radar beam from the pavement multilayer structure layer; a first image processing unit 42 that generates first image processing data by performing suppression processing to suppress ground surface reflection signals on the two-dimensional image data; a second image processing unit 43 that generates second image processing data by performing sharpening processing to sharpen boundaries between layers of the pavement multilayer structure layer on the first image processing data; and a thickness calculation unit 44a that calculates the pavement thickness and the base course thickness from the second image processing data.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an inspection device that uses a ground-penetrating radar to inspect the condition of a multi-layered pavement layer in which buried pipes are buried, while moving along the surface of the multi-layered pavement layer. [Background technology]

[0002] When an exploration device using a ground penetrating radar scans along a scanning line set in a search range including buried pipes buried underground, it processes the reflected waves of the exploration electromagnetic waves emitted toward the ground, acquires cross-sectional data showing the buried state of the buried pipes in a vertical cross-section including the scanning line, and displays the cross-sectional data on a display unit. For example, in the exploration device disclosed in Patent Document 1, cross-sectional data is acquired based on multiple scanning lines parallel to each other in the search range, and buried pipe markers are set in the acquired cross-sectional data at positions where buried pipes may exist. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-57235 Summary of the Invention [Problem to be solved by the invention]

[0004] When working on buried pipes such as gas and water pipes, it is important not only to know the location of the pipes, but also to predict the condition of the multi-layered pavement structure in which the pipes are buried. When working on buried pipes, excavation work is first carried out to expose the buried pipes. During this work, if the pavement thickness confirmed in the construction drawings is much thicker than the hard roadbed containing asphalt or cement, a problem arises in which the construction costs will be higher than expected.

[0005] However, although the exploration device described in Patent Document 1 can obtain the position information of the buried pipe, it cannot obtain information about the multi-layered pavement layer in which the buried pipe is buried. Therefore, there is a demand for an exploration device that can obtain information about the multi-layered pavement layer in which the buried pipe is buried. [Means for solving the problem]

[0006] The exploration device of the present invention, which uses an underground radar to explore the condition of a pavement multi-layer layer in which a buried pipe is buried, moves along the surface of the pavement multi-layer layer and comprises: a reflection signal processing unit that generates two-dimensional image data showing a cross-section of the pavement multi-layer layer based on the reflection signal of the emitted radar beam from the pavement multi-layer layer; a first image processing unit that generates first image processing data by performing a suppression process to suppress the ground surface reflection signal in the two-dimensional image data; a second image processing unit that generates second image processing data by performing a sharpening process to sharpen the boundaries of each layer that makes up the pavement multi-layer layer in the first image processing data; and a thickness calculation unit that calculates the thickness of the pavement and the thickness of the roadbed from the second image processing data.

[0007] According to this configuration, first image processing data is generated from two-dimensional image data showing a cross-sectional image based on the reflection signals from each layer of the pavement multi-layer structure, in which ground surface reflection signals with large amplitudes, rather than reflection signals from each underground layer, are suppressed. Second image processing data is then generated from the first image processing data, in which the boundaries of each layer of the pavement multi-layer structure are sharpened. Because the pavement multi-layer structure includes a pavement layer such as asphalt pavement and a subgrade layer supporting the pavement, the thickness of the pavement (pavement thickness) and the subgrade thickness (subgrade thickness) can be calculated from the second image processing data. Because buried pipes are buried beneath the pavement and subgrade, the thickness of the pavement and the subgrade, which are information about the pavement multi-layer structure layer in which the buried pipes are buried, can be determined by an inspection device that inspects the buried pipes. As a result, construction costs for the buried pipes can be estimated more accurately. The pavement multi-layer structure consists of, from the ground surface, the pavement, the subgrade, and the roadbed.

[0008] When excavating a multi-layered pavement structure in buried pipe construction, incisions are made in the pavement structure in advance to ensure smooth construction. However, if the hardness of the pavement structure, particularly the roadbed, is found to be harder than expected, inconveniences such as the need to prepare special tools and increased construction costs for the incisions can occur. To avoid this problem, it is necessary to accurately determine the roadbed hardness in advance. For this reason, the present invention includes a hardness evaluation unit that calculates the multiple reflection characteristics of the radar beam generated at the boundary region between the roadbed and the roadbed from the 2D image data and determines the hardness of the roadbed based on the multiple reflection characteristics. This exploration device can determine the hardness of the roadbed based on the multiple reflection waves generated by the boundary between the pavement and the roadbed and by boundaries within the roadbed.

[0009] The ground surface reflection signals in the 2D image data, which are the exploration data acquired at the beginning of the exploration, are based on surface reflection waves from the ground surface, which is the scanning plane of the exploration device. Therefore, the surface reflection waves, which are the locus of the reflection points, extend substantially in the horizontal direction in a cross-sectional image, with the horizontal axis being the scanning direction and the vertical axis being the depth direction of the pavement multi-layer structure layer. Therefore, by setting filter parameters that can remove (suppress) the surface reflection waves in a 1D FFT (Fast Fourier Transform) process and filtering, the surface reflection waves can be substantially removed from the 2D image data. Alternatively, by performing a correlation process on the standard surface reflection waves created from the acquired 2D image data with the 2D image data, the surface reflection waves can be substantially removed from the 2D image data. The cross-sectional image from which the surface reflection waves have been removed can be visually understood more easily. For this reason, the present invention proposes that the suppression process include 1D FFT processing and correlation processing.

[0010] The reflected waves from the boundaries of each layer of the pavement multi-layer structure in the first image processing data are reflected from reflection sources at various depths in each layer, and have a complex shape, i.e., contain many frequency components. In other words, the reflected waves are waveforms that spread in the horizontal and vertical directions in the cross-sectional image, and two-dimensional FFT processing is suitable for shaping (filtering) them into an appropriate shape. For this reason, in the present invention, it is proposed that the sharpening process includes two-dimensional FFT processing.

[0011] As a specific example of sharpening processing based on two-dimensional FFT processing, a two-dimensional Fourier transform is performed on first image processing data, and filter processing parameters are set based on the result of the two-dimensional Fourier transform (Fourier transform data), followed by filter processing. By performing an inverse Fourier transform on the filtered Fourier transform data, second image processing data is obtained as a boundary-sharp image in which the boundaries of each layer of the pavement multi-layer structure are sharpened. Such second image processing data is not only suitable for calculating the thickness and hardness of the pavement or roadbed, but also for visually understanding them. For this reason, the present invention proposes that the sharpening processing generates, as the second image processing data, a boundary-sharp image in which the boundaries have been sharpened by performing a two-dimensional Fourier transform, filter processing, and inverse Fourier transform on the first image processing data.

[0012] As a more specific example of the sharpening process, the present invention proposes that the sharpening process is a process of obtaining a sharpened image consisting of multiple horizontal lines in which each layer of the pavement multi-layer structure is sharpened by image subtraction, in which a horizontal stripe-removed image obtained by the horizontal stripe removal filter process and inverse Fourier transform in the two-dimensional FFT process is subtracted from a surface wave-suppressed image in which the ground surface reflection signals have been suppressed by the suppression process.As a result, it becomes easier to evaluate the condition of the roadbed, which is a constituent layer of the pavement multi-layer structure (such as layer thickness and layer hardness).

[0013] It is preferable that the surveyor can check the condition of the pavement multi-layer structure layers simultaneously with the survey using the surveying device. To this end, the surveyor should be provided with a monitor screen, and the survey image (two-dimensional image data, first image processing data, second image processing data) that is a cross-sectional image of the pavement multi-layer structure layer as described above should be visualized and displayed on the monitor screen. While an experienced surveyor can read the thickness and hardness of the pavement and roadbed from the monitor screen, it is preferable for an unskilled surveyor to display numerical values ​​of the pavement and roadbed thickness and hardness calculated by the surveying device on the monitor screen. For this reason, the present invention proposes that a monitor device that displays the survey status be provided, and that the monitor device be configured to display an survey image display screen that displays the survey image that is a cross-sectional image based on the second image processing data, and an survey result display screen that displays the survey results including the pavement thickness and the roadbed thickness.

[0014] Other features, operations, and advantages of the present invention will become apparent from the following description of the invention using the accompanying drawings. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram of an exploration device. [Figure 2] FIG. 2 is a functional block diagram showing functions of the exploration device. [Figure 3] FIG. 2 is a schematic diagram illustrating a pavement multi-layer structure layer and its relationship to a survey image. [Figure 4] FIG. 10 is a transition diagram of an exploration image that changes due to image processing in the exploration device. [Figure 5] FIG. 2 is a screen diagram showing an example of a display screen of a monitor device. [Figure 6] FIG. 10 is a screen diagram showing another example of the display screen of the monitor device. DETAILED DESCRIPTION OF THE INVENTION

[0016] (Outline of the exploration device) As shown in FIGS. 1 and 2, an exploration device 1 according to an embodiment of the present invention can be manually pushed by an explorer or can travel automatically. The exploration device 1 explores underground, i.e., a buried pipe X buried in a pavement multi-layer structure layer 2 as shown in FIG. 3, by traveling along a set scan line SL. As the exploration device 1 travels along the scan line SL, a radar beam, which is an electromagnetic wave used for exploration, is emitted underground. A reflected signal, which is a reflected wave of the radar beam reflected by the pavement multi-layer structure layer 2 and returned to the exploration device 1, is processed by a control unit 4 of the exploration device 1. The control unit 4 generates an exploration image (cross-sectional image), which is a two-dimensional image showing the state of the pavement multi-layer structure layer 2 and the buried state of the buried pipe X in a vertical cross section including the scan line SL. The exploration image, which is an example of the exploration situation, is displayed on a monitor device 10 installed above the exploration device 1.

[0017] As shown in FIG. 3, the pavement multi-layer structure layer 2 is, for example, composed of, in order from the ground surface (road surface), a pavement 21 consisting of a surface asphalt layer 21a and a base asphalt layer 21b, a roadbed 22 consisting of an upper roadbed 22a and a lower roadbed 22b, and a roadbed 23. A buried pipe X is buried in the roadbed 23. A radar beam emitted to the pavement multi-layer structure layer 2 is reflected by the ground surface, each layer of the pavement multi-layer structure layer 2, and the buried pipe X. The reflected wave of the radar beam, which is a reflection signal, is converted into two-dimensional image data by the control unit 4 and displayed on the monitor device 10 as a detection image as shown on the right side of FIG. 3. Note that the horizontal axis of the detection image represents the traveling direction of the detection device 1, and the vertical axis represents the depth direction of the pavement multi-layer structure layer 2. In this detection image, a group of reflected waves reflected at each location is shown as a straight line or a wave in the horizontal axis direction. The reflected wave from buried pipe X creates a curved wave that protrudes upward and is located at the bottom of the survey image.

[0018] (Detailed configuration of the exploration device) As shown in Fig. 2, the exploration device 1 is broadly composed of an antenna 9, a control unit 4, and a monitor device 10. The control unit 4 converts the reflected signal of the radar beam received by the antenna 9 into two-dimensional image data and then processes the image, and the monitor device 10 displays the exploration image data (also simply referred to as an exploration image) image-processed by the control unit 4 in a visualized form. The exploration image data includes first image processing data and second image processing data, as will be described later.

[0019] The antenna 9 comprises a transmitting antenna 9a and a receiving antenna 9b, but these may be integrated as a transmitting and receiving antenna. The transmitting antenna 9a emits a radar beam, which is a pulsed electromagnetic wave in the microwave range, toward the pavement multi-layer structure layer 2 at a predetermined repetition frequency, and the receiving antenna 9b receives the reflected wave reflected from each layer of the pavement multi-layer structure layer 2 and the buried pipe X, and provides it to the control unit 4 as a reflected signal.

[0020] The exploration device 1 travels along a scanning line SL, and is equipped with a position detection sensor unit (not shown) that detects the distance or point of movement of the exploration device 1. This position data is sent to the control unit 4, correlated with a reflected signal, which is a wave reflected from the ground, and used to generate an exploration image. The position detection sensor unit can be simply constructed using a rotary encoder connected to the traveling wheels, but it may also be constructed using a GNSS or gyro.

[0021] The monitor device 10 is equipped with a touch panel 10A that displays the exploration images, messages indicating the exploration results, etc. so that the explorer can visually confirm them. The explorer can also issue various operation commands to the control unit 4 through the touch panel 10A. The touch panel 10A is mounted on the top surface of the exploration device 1 and can be set to any inclined position so that it can be clearly seen by the explorer operating the exploration device 1.

[0022] The control unit 4 is configured as a computer system in which each function is constructed with hardware and software, as shown in Fig. 2. The control unit 4 includes, as functional parts, a transmitting / receiving part 40, a reflected signal processing part 41, a first image processing part 42, a second image processing part 43, a structural layer evaluation part 44, and a display control part 45.

[0023] FIG. 4 shows how the two-dimensional image data generated in the control unit 4 based on the reflected signal of the radar beam undergoes various image processing steps and transitions.

[0024] The transmitter / receiver unit 40 generates an excitation signal to generate a radar beam, which is a pulsed electromagnetic wave, and provides it to the transmitting antenna 9a. It also receives the reflected wave received by the receiving antenna 9b, generates a reflected signal, and provides it to the reflected signal processing unit 41.

[0025] The reflected signal processing unit 41 generates two-dimensional image data showing a vertical cross section of the scanning line SL in the area of ​​the pavement multi-layer structure layer 2 based on the appropriately amplified received signal and position data from a position detection sensor unit (not shown). An example of a two-dimensional image visualizing this two-dimensional image data is shown on the right side of FIG. 3. This two-dimensional image is a so-called initial exploration image acquired first, and it includes waveforms showing each layer of the pavement multi-layer structure layer 2 and the buried pipe X. In general, the reflection from the interface (road surface) between the atmosphere and the surface asphalt 21a is strong, the reflection from the interface between the surface asphalt 21a and the base asphalt 21b is weak, the reflection from the interface between the base asphalt 21b and the upper roadbed 22a is strong, the reflection from the interface between the upper roadbed 22a and the lower roadbed 22b is strong, the reflection from the interface between the lower roadbed 22b and the roadbed 23 is weak, and the reflection from the surface of the buried pipe X buried in the roadbed 23 is strong. It is particularly noteworthy that when the roadbed 22 is formed hard by including a large amount of cement components due to heavy traffic, multiple reflections occur between the base layer asphalt 21b and the hard roadbed 22. These reflection characteristics are reflected in the detection image based on the 2D image data. An example of an image visualized from this 2D image data is shown in Figure 4 (1).

[0026] The first image processing unit 42 generates first processed image data by performing suppression processing on the two-dimensional image data generated by the reflected signal processing unit 41 to suppress ground surface reflected signals. This suppression processing includes one-dimensional FFT processing and correlation processing. Since one-dimensional FFT processing and correlation processing are well-known image processing methods, detailed description thereof will be omitted. However, in the one-dimensional FFT processing, filter parameters capable of removing (suppressing) surface reflected waves are set based on the results of the one-dimensional FFT processing. By filtering the two-dimensional image data with a filter having these parameters, the waveform of the surface reflected waves is substantially removed from the two-dimensional image data, leaving a straight horizontal line indicating the road surface (ground surface). In addition, in the correlation processing, a standard surface reflected wave created from the acquired two-dimensional image data is correlated with the two-dimensional image data, thereby substantially removing the surface reflected waves from the two-dimensional image data, leaving a straight horizontal line indicating the road surface (ground surface). An example of an image visualizing the first processed image data is shown in (2) of FIG. 4.

[0027] The second image processing unit 43 performs a sharpening process on the first image processing data generated by the first image processing unit 42 to sharpen the boundaries of each layer of the pavement multi-layer structure layer 2, generating second image processing data, which is a boundary-sharp image (sharpened image). This sharpening process includes a two-dimensional FFT process. Since the two-dimensional FFT process itself is a well-known image processing method, a detailed description is omitted. In brief, the filter processing parameters are set based on the Fourier transform data obtained by the two-dimensional Fourier transform, and filtering, for example, filtering with a DC component θ = 7 degrees, is performed. Furthermore, the second image processing unit 43 generates second image processing data by performing an inverse Fourier transform on the filtered Fourier transform data. In the second image processing data, the boundaries of each layer of the pavement multi-layer structure layer 2 are sharpened. Due to this sharpening, the reflected waves, which showed complex waveforms in the second image processing data, are suppressed, resulting in substantially straight horizontal lines. An example of an image visualizing this second image processing data is shown in (3) of Figure 4.

[0028] The image in Figure 4 (3) can also be obtained by image subtraction, which subtracts the horizontal stripe-removed image (i.e., an image containing essentially only waveform elements) obtained by horizontal stripe removal filter processing and inverse Fourier transform in two-dimensional FFT processing from the image in Figure 4 (2), which is a surface wave-suppressed image in which the ground surface reflection signal is suppressed.

[0029] Furthermore, the second image processing unit 43 can also generate third image processing data by removing only the straight horizontal line components in the second image processing data from the first image processing data. When this third image processing data is visualized, an image showing only the curved waveform (hyperbolic waveform) is obtained.

[0030] In order to calculate the pavement thickness, it is necessary to determine the horizontal line indicating the road surface and the linear horizontal line indicating the boundary between the base asphalt layer 21b and the upper subgrade 22a. In addition, in order to calculate the subgrade thickness, it is necessary to determine the linear horizontal line indicating the boundary between the base asphalt layer 21b and the upper subgrade 22a and the boundary between the lower subgrade 22b and the roadbed 23. Therefore, the second image processing unit 43 performs image processing to clarify the horizontal lines. Figure 4 (4) shows an image that combines Figure 4 (2) and Figure 4 (3) and has been processed to highlight the first horizontal line indicating the boundary between the pavement 21 and the roadbed 22 (denoted by the symbol L1 and drawn darker in Figures 4 and 5) and the second horizontal line indicating the boundary between the roadbed 22 and the roadbed 23 (denoted by the symbol L2 and drawn darker in Figures 4 and 5).

[0031] The structural layer evaluation unit 44 evaluates the condition of each layer of the pavement multi-layer structure layer 2 from the second image processing data based on the second image processing data. The structural layer evaluation unit 44 includes a thickness calculation unit 44a that calculates the thickness of the pavement 21 and the thickness of the roadbed 22, and a hardness evaluation unit 44b that evaluates the roadbed hardness. The thickness calculation unit 44a calculates, as the pavement thickness, the distance in the depth direction (vertical axis) between the horizontal line indicating the road surface and the reflected wave (straight horizontal line) from the boundary surface between the base asphalt layer 21b and the upper roadbed 22a. Furthermore, the thickness calculation unit 44a calculates, as the roadbed thickness, the distance in the depth direction (vertical axis) between the reflected wave (straight horizontal line) from the boundary surface between the base asphalt layer 21b and the upper roadbed 22a and the reflected wave (straight horizontal line) from the boundary surface between the lower roadbed 22b and the roadbed 23. Alternatively, the thickness calculation unit 44a calculates the roadbed thickness as the distance in the depth direction (vertical axis) between the reflected wave (straight horizontal line) from the boundary surface between the base asphalt 21b and the upper roadbed 22a and the reflected wave (straight horizontal line) from the boundary surface between the upper roadbed 22a and the lower roadbed 22b.

[0032] The hardness evaluation unit 44b of the structural layer evaluation unit 44 determines the multiple reflection characteristics of the radar beam in the boundary region of the roadbed 22, particularly the boundary region between the pavement 21 and the upper roadbed 22a and the boundary between the upper roadbed 22a and the lower roadbed 22b, from the complex and finely distributed reflected waves (appearing as multiple thin (e.g., three or more) horizontal lines in the image) that occur in this boundary region with the roadbed 23 located below the roadbed 22. Because a hard roadbed 22 contains a large amount of cement, the multiple reflection characteristics of the reflected waves due to the cement component are an important factor in determining the hardness of the roadbed 22. Arithmetic processing such as Fourier transform can be used to evaluate the multiple reflection characteristics. Alternatively, the hardness of the roadbed 22 can be determined using pattern recognition technology with probe images obtained by testing pavement multi-structure layers 2 with various roadbed 22 hardnesses.

[0033] In addition, in order to confirm the evaluation of the condition of the pavement multi-layer structure layer 2 by the structure layer evaluation unit 44, or for the explorer to evaluate the condition of the pavement multi-layer structure layer 2 himself, the desired image from images (1) to (4) in Figure 4 can be displayed on the monitor device 10.

[0034] The display control unit 45 includes a display data generation unit 45a and an operation command processing unit 45b. The display data generation unit 45a generates and manages the display data to be displayed on the touch panel 10A of the monitor device 10. The operation command processing unit 45b interprets operation commands given by the explorer via software buttons arranged on the touch panel 10A, and issues operation commands to the display data generation unit 45a and other functional units.

[0035] 5 and 6 show examples of the display screen of the touch panel 10A of the monitor device 10. The touch panel 10A is assigned an exploration image display screen 11 that displays exploration images ((1) to (4) in FIG. 4), which are cross-sectional images based on the second image processing data, and an operation button display screen 12 on which software buttons and the like are arranged. Furthermore, as shown in FIG. 6, the touch panel 10A also displays an exploration result display screen 13 as a pop-up screen that displays the exploration results such as pavement thickness and roadbed thickness by the thickness calculation unit 44a.

[0036] [Another embodiment] (1) In the above-described embodiment, the structural layer evaluation unit 44 has a function of determining the hardness of the roadbed 22. However, this function may be omitted, and the hardness of the roadbed 22 may be determined by an inspector from an inspection image such as (4) in Figure 6 displayed on the touch panel 10A.

[0037] (2) The functional blocks shown in Figure 2 represent only one embodiment of the exploration device 1. For example, at least some of the functions of the control unit 4 and the monitor device 10 can be implemented in a computer system separate from the rover that transmits and receives radar beams, and the computer system and the rover can be connected via a wireless or wired communication line.

[0038] The configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradiction arises. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0039] The present invention is applicable to an exploration device that uses a ground penetrating radar to explore buried pipes. [Explanation of symbols]

[0040] 1: Exploration equipment 2: Multi-layer pavement structure 4: Control unit 9: Antenna 9a: Transmitting antenna 9b: Receiving antenna 10: Monitor device 10A: Touch panel 11: Exploration image display screen 13: Search result display screen 21: Pavement 21a: Surface asphalt 21b: Base asphalt 22: Roadbed 22a: Upper roadbed 22b: Lower roadbed 23: Roadbed 40: Transmitter / receiver 41: Reflection signal processing section 42: First image processing unit 43: Second image processing unit 44: Structural layer evaluation section 44a: Thickness calculation section 44b: Hardness evaluation section 45: Display control section 45a: Display data generation unit 45b: Operation command processing section X: Buried pipe

Claims

1. 1. An exploration device that uses a ground-penetrating radar to explore the condition of a multi-layered pavement layer in which a buried pipe is buried, while moving along the surface of the multi-layered pavement layer, a reflection signal processing unit that generates two-dimensional image data showing a cross section of the pavement multi-layer structure layer based on a reflection signal of the emitted radar beam from the pavement multi-layer structure layer; a first image processing unit that generates first image processing data by performing suppression processing to suppress ground surface reflection signals in the two-dimensional image data; a second image processing unit that generates second image processing data by performing a sharpening process that sharpens the boundaries of each layer that constitutes the pavement multi-layer structure layer in the first image processing data; a thickness calculation unit that calculates a thickness of a pavement and a thickness of a roadbed from the second image processing data; An exploration device equipped with

2. 2. The inspection device according to claim 1, further comprising a hardness evaluation unit that determines, from the two-dimensional image data, the multiple reflection characteristics of the radar beam generated in a boundary region in the roadbed, and determines the hardness of the roadbed based on the multiple reflection characteristics.

3. The exploration device according to claim 1 , wherein the suppression processing includes one-dimensional FFT processing and correlation processing.

4. The exploration device according to claim 1 , wherein the sharpening process includes a two-dimensional FFT process.

5. 5. The exploration device according to claim 4, wherein the sharpening process performs a two-dimensional Fourier transform, a filtering process, and an inverse Fourier transform on the first image processing data to generate a boundary-sharp image in which the boundary has been sharpened as the second image processing data.

6. The exploration device described in claim 4, wherein the sharpening process is a process of obtaining a sharpened image consisting of a plurality of horizontal lines in which each layer of the pavement multi-layer structure layer has been sharpened by image subtraction, in which a horizontal stripe-removed image obtained by horizontal stripe removal filter processing and inverse Fourier transform in the two-dimensional FFT processing is subtracted from a surface wave-suppressed image in which the ground surface reflected signals have been suppressed by the suppression process.

7. 7. The exploration device according to claim 1, further comprising a monitor device for displaying the exploration status, the monitor device displaying an exploration image display screen for displaying an exploration image, which is a cross-sectional image based on the second image processing data, and an exploration result display screen for displaying the exploration results including the thickness of the pavement and the thickness of the roadbed.

Images