JP2001272467A - Three-dimensional voxel data displaying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge automatically a suitable propagation velocity with a central value by setting the central value for estimating the visibility of an image every propagation velocity when three-dimensional voxel data are displayed with an image. SOLUTION: This three-dimensional voxel data (x, y, t) displaying method includes a process which executes migration treatment or synthetic aperture treatment for the every data propagation velocity and forms the every data propagation velocity, a maximum absolute value extracting process which extracts the maximum absolute value of amplitude values in the reflection time t axis direction every position (x, y) of a medium surface with respect to the data, a plane arrangement process which arranges the maximum absolute values on a prescribed plane and forms an image, a central value calculating process which calculates the central value for estimating the visibility of the image, a propagation velocity selecting process which selects a suitable propagation velocity from the plurality of propagation velocities on the basis of the central value, and a display process which displays the maximum absolute value or the data for each of the positions (x, y) on a medium surface corresponding to the propagation velocities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a function of a position (x, y) of a surface of a medium and a reflection time t, which is generated based on a reflection signal intensity of a wave signal radiated from the surface of the medium into the medium. And a method for displaying three-dimensional voxel data (x, y, t).

[0002]

2. Description of the Related Art Such a three-dimensional voxel data display, for example, in the search for an underground object, emits a wave signal by electromagnetic waves or sound waves while moving on the ground surface, and exists in the ground. A reflected signal from an object is received, and a position (x,
y) and three-dimensional voxel data (x, y, t), which is a function of the reflection time t, were subjected to migration processing and synthetic aperture processing according to the value of the relative dielectric constant (propagation velocity) in an appropriate medium. The results are shown in the three-dimensional data display method (planar image) disclosed in Japanese Patent Application No. 11-330966,
An image is displayed as an image by a technique called a surface display type (three-dimensional image) which is a conventional technique disclosed in 1-3330966. FIGS. 10 to 12 show examples in which the results of processing at relative dielectric constants of 5, 3, and 7 are displayed as (a) a planar image or (b) a three-dimensional image by the above two methods, respectively.

[0003]

In the above-described method, the result of the migration processing at a plurality of arbitrarily set propagation speeds is converted into an image, and an operator compares the plurality of images to estimate an optimum propagation speed. Was. Therefore, there is a problem that it takes time and effort to estimate the optimum image.

[0004] The present invention has been made in view of the above problems, and when displaying three-dimensional voxel data as an image, a representative value for evaluating the sharpness of the image is set for each propagation speed. The purpose is to automatically determine an appropriate propagation speed based on a representative value.

[0005]

A first feature of the present invention to achieve this object is a three-dimensional voxel data display according to the present invention as described in claim 1 of the claims. A method includes generating a three-dimensional voxel data (x) that is a function of a position (x, y) of the medium surface and a reflection time t generated based on a reflection signal intensity of a wave signal emitted from the medium surface into the medium. , Y, t), wherein a migration process or a synthetic aperture process is performed on the original three-dimensional voxel data consisting of the reflection signal intensity for each of a plurality of arbitrarily set propagation velocities in the medium. Generating the three-dimensional voxel data for each propagation velocity; and calculating the three-dimensional voxel data for each propagation velocity in the reflection time t-axis direction for each position (x, y) of the medium surface. Amplitude value A maximum absolute value extracting step of extracting a maximum absolute value, and a maximum absolute value for each position (x, y) of the medium surface extracted in the maximum absolute value extracting step is arranged on a predetermined plane to form an image. A plane arrangement step, a representative value calculation step for calculating a representative value for evaluating the sharpness of the image formed in the plane arrangement step, and the plurality of the plurality of images based on the representative value calculated in the representative value calculation step. A propagation velocity selecting step of selecting an appropriate propagation velocity from the propagation velocity of the medium; and a position (x, x) of the medium surface corresponding to the propagation velocity selected in the propagation velocity selecting step.
y) for displaying the maximum absolute value or the three-dimensional voxel data for each y).

Here, the amplitude value of the voxel means the intensity of the reflected signal at the coordinates (x, y, t) or the intensity of the signal after the predetermined signal processing. Depending on the device configuration or the like, either one or both polarities can be taken.

[0007] The representative value for evaluating the sharpness of an image is, more specifically, a statistical texture feature representing the degree of focus of the image. Here, the statistical texture feature amount includes a density histogram, a co-occurrence matrix,
It refers to difference statistics, run-length matrices, power spectra, etc.

In the second feature configuration, in addition to the first feature configuration, in the maximum absolute value extracting step, the position of the medium surface ( The point is that when extracting the maximum absolute value for each of x, y), an amplitude value outside a predetermined range in the reflection time t-axis direction is excluded.

In the third feature configuration, in addition to the first or second feature configuration, in the maximum absolute value extracting step, the surface of the medium may be added to the first or second feature configuration. When the maximum absolute value is extracted for each position (x, y), the extraction is performed on voxels whose polarity of the amplitude value is either positive or negative.

[0010] In the fourth feature configuration, in addition to the first, second or third feature configuration, the representative value is a variance value, as described in claim 4 of the claims. On the point.

According to a fifth aspect of the present invention, in addition to the first, second, or third aspect, the representative value is a contrast value. On the point.

In a sixth aspect, the representative value is an entropy value in addition to the first, second, or third aspect, as described in claim 6 of the claims. On the point.

[0013] A seventh characteristic configuration is that, as described in claim 7 of the claims, the three-dimensional voxel data display device according to the present invention provides a three-dimensional voxel data display device of the wave signal radiated from the surface of the medium into the medium. A display device for displaying three-dimensional voxel data (x, y, t), which is a function of a position (x, y) of the medium surface and a reflection time t, generated based on a reflection signal intensity,
Performing a migration process or a synthetic aperture process on the original three-dimensional voxel data composed of the reflection signal intensity for each of a plurality of arbitrarily set propagation velocities in the medium,
Three-dimensional voxel data generating means for generating the three-dimensional voxel data for each propagation velocity; and a reflection time t for each position (x, y) of the medium surface with respect to the three-dimensional voxel data for each propagation velocity. Maximum absolute value extracting means for extracting the maximum absolute value of the amplitude value in the axial direction; and the maximum absolute value for each position (x, y) of the medium surface extracted by the maximum absolute value extracting means arranged on a predetermined plane. A plane arrangement unit for forming an image; a representative value calculation unit for calculating a representative value for evaluating the sharpness of the image formed by the plane arrangement unit; and the representative value calculated by the representative value calculation unit. A propagation speed selecting means for selecting an appropriate propagation speed from the plurality of propagation speeds, and the medium speed corresponding to the propagation speed selected by the propagation speed selecting means. Location (x, y) the maximum absolute value for each, or in a point which is a display means for displaying the three-dimensional voxel data.

In an eighth aspect, the computer-readable recording medium according to the present invention is adapted to display the three-dimensional voxel data of the first aspect as described in claim 8 of the claims. Performing the migration processing or the synthetic aperture processing in the method for each of a plurality of arbitrarily set propagation velocities in a medium;
A program for causing one or two or more computers to execute processing for generating three-dimensional voxel data, and for each of the three-dimensional voxel data, the maximum absolute value extraction step, the plane arrangement step, and the representative value calculation step And a program for causing the computer to execute the program for each of the propagation speeds, and a program for causing the computer to execute the propagation speed selection step and the display step.

The operation and effect of these features will be described below.

According to the first characteristic configuration, the synthetic aperture processing or the migration processing is executed using a plurality of arbitrarily set propagation velocities in the medium, and the three-dimensional voxel data generated for each propagation velocity is obtained. The maximum absolute value is arranged in the plane arrangement process, a representative value for evaluating the sharpness of the object image obtained from the maximum absolute value arranged on the plane is calculated, and the propagation speed when the representative value is maximum is automatically calculated. To obtain 3D voxel data that has been subjected to migration processing or synthetic aperture processing at an appropriate propagation speed in the medium, and consequently obtains a high-definition maximum absolute value image or 3D voxel data display. Can be.

According to the second characteristic configuration, when extracting the maximum absolute value of the amplitude value in the direction of the reflection time t-axis for each position (x, y) on the surface of each medium, the predetermined range of the reflection time t is determined. In the case of underground exploration, regions where the reflected signal intensity in the medium is extremely strong, such as near the surface of the ground or underground water, can be excluded in order to exclude the amplitude values outside, and as a result, the object region in the medium can be excluded. It is possible to improve the visibility with respect to the (buried object area in the case of underground object exploration).

According to the third characteristic configuration, when the maximum absolute value of the amplitude value in the direction of the reflection time t-axis for each position (x, y) on each medium surface is extracted, the polarity of the amplitude value is positive. Alternatively, by targeting only one of the negative voxels, only the amplitude value of the higher polarity of the S / N ratio of the reflected signal from the object in the medium is extracted, so that the object region in the medium can be visually recognized. Performance can be improved. This is due to the fact that in the case of underground exploration, the reflection coefficient of the radiated signal at the buried object has a different polarity depending on the material of the buried object. In the case of a cavity or a cavity, it has a positive reflection coefficient.

According to the fourth to sixth feature configurations, the variance value, contrast value, or entropy value is a statistical texture feature amount as a representative value, and can be used as a representative value for evaluating the sharpness of an image. From the relationship between the propagation speed and each of the representative values, it is possible to accurately select a propagation speed capable of clearly displaying an object image, that is, a propagation speed in a medium. Further, these variance values, contrast values, and entropy values are suitable for easy and high-speed computer processing, and the representative value calculation step can be performed quickly.

According to the seventh aspect, the synthetic aperture processing or the migration processing is executed by using the propagation velocities in a plurality of media, and the maximum absolute value of the three-dimensional voxel data generated for each propagation velocity is calculated on a plane. And a device for calculating a representative value for evaluating the sharpness of the object image obtained from the maximum absolute value arranged on the plane, and automatically selecting a propagation speed when the representative value is maximized. As a result, three-dimensional voxel data subjected to migration processing or synthetic aperture processing at an appropriate propagation speed in the medium can be obtained, and as a result, a maximum absolute value image or three-dimensional voxel data display with high definition can be obtained.

According to the eighth aspect, once the program recorded on the recording medium is installed in the main storage area of the computer, the program on the main storage area is executed, so that the program is stored in the computer. The first to sixth three-dimensional voxel data display methods can be executed. As a result, the same functions and effects as those of the method for displaying three-dimensional voxel data having the first to sixth characteristic configurations are exhibited.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the underground objects 3
An embodiment when applied to dimensional exploration will be described with reference to the drawings. As shown in FIG.
The three-dimensional exploration device 3 including the three-dimensional voxel data display device includes a transceiver 10 as a transmission / reception unit and a transceiver 10
And a data analysis device 20 for processing the signal obtained in step (1). In the present application, the analysis process in the data analysis device 20 has the feature.

As shown in FIG. 1, an object 2 such as a steel pipe for delivering a fluid such as a gas is buried in a soil 1 as a medium, and an exploration device 3 having a transceiver 10 and a data analyzer 20 is provided. The buried position of the object 2 is searched while moving on the ground surface. The moving direction is the x direction. Then, when obtaining three-dimensional voxel data as in the present application, after collecting data in the x direction, the y direction (the front and back direction in FIG. 1)
, The x-direction data is sequentially collected while repeating a predetermined amount of movement. The object 2 shown in FIG. 1 schematically illustrates an object to be searched, and shows, for example, a part of the buried pipe 32 in a buried state as shown in FIG.

The transceiver 10 is, for example, 100 MHz to 1
A single-pulse signal illustrated in FIG. 2B and FIG. 2A at 1 GHz is generated in the transmission circuit 13 and radiated from the transmission antenna 11 to the soil 1 as an electromagnetic wave. For example, when moving on the surface of the object 2 as illustrated in FIG.
Incident wave 4 incident on soil in electromagnetic waves radiated from 1
Is reflected and scattered on the surface of the object 2, and after the reflected wave 5 therein is received by the receiving antenna 12, the signal is demodulated and amplified in the receiving circuit 14 as a received signal as exemplified in FIGS. (In this figure, a single line corresponds to a plurality of received signal groups received at fixed positions with a time difference). The time difference between the radiation from the transmitting antenna 11 and the reception by the receiving antenna 12 (this is a substantial reflection time) t is the distance from the surface of the soil 1 to the object 2 and the dielectric constant ε of the soil 1 or the propagation speed of the electromagnetic wave. Is uniquely determined from FIG.
In the case shown in (1), the transmitting antenna 11 and the receiving antenna 12 are arranged at a fixed interval so as to face the ground surface. x
The directional movement is performed so as to cross the object 2.

As shown in FIG. 1, the transceiver 10 is provided with signal intensity modulating means 15 for modulating the gain of the amplifying section of the receiving circuit 14 in accordance with the time difference t. 1, the loss of the pulse signal propagating through 1 increases, and the amplitude of the received signal strength (same as the reflected signal strength) is corrected to be attenuated. It is configured to obtain an intensity distribution. With this configuration, it is possible to secure the signal strength necessary for the subsequent signal processing.

Next, the data analyzer 20 to which a received signal is sent will be described with reference to FIGS. The data analysis device 20 includes a data processing unit 21 including a microcomputer, a semiconductor memory, and the like, and an input unit 2 such as a mouse and a keyboard for inputting an operation instruction from the outside.
2 and a display unit 23 such as a CRT monitor or a liquid crystal display for displaying image data and output results at each processing stage. Further, an external auxiliary storage unit 24 such as a magnetic disk for storing data and output results at each processing stage is provided.

As shown in FIG. 3, the data processing unit 21
Comprises three-dimensional voxel data generating means 25 for organizing and processing a received signal input from the receiving circuit 14 for each of a plurality of propagation velocities in relation to a position (x, y) on the medium surface and time t. ing.

This three-dimensional voxel data generating means 25
Is for generating three-dimensional voxel data to be used in the subsequent processing. First, an original three-dimensional data in which the received signal strength s is used as it is as a function of the position (x, y) on the medium surface and the time t The voxel data s (x, y, t) is generated.
Further, the original three-dimensional voxel data s (x, y, t)
Is subjected to migration processing, and new three-dimensional voxel data S (x, y, t) that has undergone migration processing is generated.

The migration process is performed using a program for the migration process with an arbitrarily set propagation velocity in the medium as an input variable. Since a plurality of propagation velocities in the medium are set, different three-dimensional voxel data is obtained for each propagation velocity. The setting of the propagation speed is performed by sequentially reading out the plurality of underground propagation speeds stored in a predetermined storage area in advance, or when the plurality of underground propagation speeds are separated from each other with a fixed relation to each other. , One underground propagation velocity is calculated and set based on a relational expression representing the relation.

Here, the migration processing means the moving direction information (space, depth =) obtained on the surface of the medium.
0, time information) is converted into information in the depth direction of the medium (information of space, depth, time = 0) using a Fourier or inverse Fourier transform method based on a wave equation representing the propagation of a wave. This is a known method.

In this method, when only the x direction is targeted as spatial coordinates, x is an observation line on the surface of the medium, z is a depth taking a positive direction into the medium, and t is a propagation time. The wave field is represented by u (x, z, t), and u (x,
z (t) obtained by performing a three-dimensional Fourier transform on U (ξ, η,
ω), the migration method uses a depth field u (x, z, 0) at time t = 0 from observation data u (x, 0, t) (radar image) obtained for t> 0. (Depth section).

That is, in the phase shift method which is a kind of the migration method, the following processing is performed. 1. The observed data is subjected to a two-dimensional Fourier transform with respect to x and t to obtain U (ξ, 0, ω). 2. One line of the desired depth is obtained from U (ξ, 0, ω). 3.2. Is repeated while updating the depth to obtain the entire depth section.

On the other hand, F, which is a kind of the migration method,
In the −K migration method, the following processing is performed. 1. The observed data is subjected to a two-dimensional Fourier transform with respect to x and t to obtain U (ξ, 0, ω). 2. Find the value of the Fourier transform of the depth section in the frequency domain. 3. This value is subjected to a two-dimensional inverse Fourier transform with respect to ξ and η to obtain u (x, z, 0).

In this way, a sectional structure at t = 0 can be obtained. Here, only the x direction is described as the spatial coordinates, but the case where both the x and y directions are targets as in the present application can be handled in the same manner.

Further, the data processing unit 21 generates the three-dimensional voxel data S generated for each of a plurality of propagation speeds arbitrarily set by the three-dimensional voxel data generating means 25.
With respect to (x, y, t), a position (x, y, t) on the medium surface
y) The maximum absolute value extracting means 27 for extracting the maximum absolute value of the amplitude value in the direction of the t-axis for each reflection time for each propagation speed, and the position on the medium surface extracted by the maximum absolute value extracting means 27 (x , Y), a plane arranging means 28 for arranging the maximum absolute value on a predetermined plane for each propagation speed, and processing the maximum absolute value arranged on the plane to evaluate the sharpness of the image arranged on the plane. Value calculating means 2 for calculating a representative value to be calculated
9 and a propagation speed selecting means 30 for selecting an appropriate propagation speed by evaluating the calculated representative value for each propagation speed.
And the maximum absolute value at the selected propagation velocity or 3
A display unit 31 for outputting the dimensional voxel data and displaying the data on the display unit 23;

Here, the three-dimensional voxel data generating means 25, the maximum absolute value extracting means 27, the plane arranging means 28, the representative value calculating means 29, and the propagation speed selecting means 30 which constitute the data processing section 21 are described. And the display means 31 is such that a program for causing a computer including the above-described microcomputer, semiconductor memory, or the like to function as the respective means is installed in a main storage area of the computer and is in an executable state. Is realized by: The main storage area refers to an area in a predetermined storage device in which the program is recorded in a state where the central processing unit of the computer can sequentially execute the program. The processing device has a hierarchical structure of a semiconductor memory from which the program can be read at high speed and a nonvolatile magnetic disk memory for storing the execution program. In the case of having both the non-volatility and the non-volatility, the hierarchical structure is not necessarily required.

Next, an embodiment of the three-dimensional voxel data display method according to the present invention will be described with reference to the data processing unit 21 shown in FIG.
A description will be given based on a flowchart of a typical data processing procedure in.

1. Three-dimensional voxel data generation step (ST)
1) In this step, while moving the three-dimensional search device 3, data is collected and processed, and the three-dimensional voxel data S (x, y,
This is the step of generating t).

In this step, a cross-sectional image of the soil 1 including the object is obtained from the digitized received signal strength by using the antenna 1
The positions (x, y) on the medium surface of 1 and 12 and the reflection time t of the reflected wave 5 from the object 2 (actually, the time from the transmission of a predetermined incident signal until the reflected signal reaches the receiving antenna)
3D voxel data s (x, y,
The three-dimensional voxel data generation unit 25 performs the processing described below for each of a plurality of propagation velocities. Here, the received signal is displayed in a plurality of gradations according to its intensity, and the positive value of the signal intensity is white (high luminance), the negative value of the signal intensity is black (low luminance), and the signal intensity is 0 in the middle gradation. Captured as This gradation is, specifically,
It is expressed by 8-bit (256) gradations, where gradation 128 has a reflection signal intensity amplitude value of 0, a gradation value of 129 or more has a positive amplitude value, and a gradation value of 127 or less has a negative amplitude value. ing.
More specifically, the digitized received signal is A /
The position (x, y) on the medium surface and the reflection time t of the reflected wave 5 from the object 2 by the quantization bit width when the D conversion processing is performed.
(X, y, t) are encoded as an address signal, and are stored in the memory 21a in the data processing unit as original three-dimensional voxel data s (x, y, t) of a plurality of gradations.
Is stored in a predetermined area. Here, FIG. 6 shows a display example of the original three-dimensional voxel data relating to the buried pipe 32 in the buried state as shown in FIG. However, the image is unclear, and the embedding state cannot be checked at this stage.

Next, the original three-dimensional voxel data s (x, y, t) obtained as described above is subjected to migration processing, and the three-dimensional voxel data S (x, y, t) are generated. 3 obtained for each propagation speed after the migration process thus obtained.
The three-dimensional voxel data S (x, y, t) is replaced with the original three-dimensional voxel data s (x, y, t), and is passed to the subsequent steps as an output of the three-dimensional voxel data generation means 25.

The above three-dimensional voxel data S (x, y,
The process of generating t) is executed by installing a program for realizing the three-dimensional voxel data generating unit 25 in a main storage area of the computer and executing the program on the computer.

2. Maximum Absolute Value Extraction Step (ST2) For the three-dimensional voxel data S (x, y, t) generated in the three-dimensional voxel data generation step, the maximum absolute value extraction means 27 converts the position (x , Y), the amplitude value in the direction of the reflection time t-axis is stored in the memory 21a.
, And a maximum absolute value f (x, y), which is the maximum of the absolute values, is extracted for each of a plurality of propagation velocities. When a maximum absolute value is extracted for each position (x, y) on the surface of each medium and for each propagation velocity, a reflection time t that takes the maximum absolute value
_{MAX is} also extracted. As a result, even after the processing, the buried object area that reflects a strong signal has a certain reflection time t.
(Corresponding to the burial depth) can be easily grasped.

3. Plane arrangement step (ST3) The maximum absolute value f (x, y) for each position (x, y) on each medium surface extracted in the maximum absolute value extraction step is arranged on a predetermined plane by the plane arrangement means 28. Then, an image of the maximum absolute value f (x, y) for each propagation speed is formed.

Actually, the position (x, y) on the surface of each medium
Each time, the maximum absolute value extraction process and the
It is processed efficiently by executing. In particular,
Maximum absolute value extracted for each position (x, y) on each medium surface
f (x, y) and reflection time t_{MA X}For each propagation speed
It is stored in a predetermined area of the memory 21a. On all media surfaces
Both processes run at multiple propagation speeds for position (x, y)
Is done. Finally, for each position (x, y) on each medium surface
The maximum absolute value f (x, y) is arranged on a predetermined plane,
A maximum absolute value f (x, y) image for each speed is formed. This
, The storage area of the maximum absolute value f (x, y) is t = 0.
By assigning, the plane becomes 3D voxel data
Data S (x, y, t).

The maximum absolute value extracting means 27 and the plane arranging means 28 continuously execute the maximum absolute value extracting step and the plane arranging step for each position (x, y) on each medium surface and for each propagation speed. The program is executed by installing the program in the main storage area of the computer and executing the program on the computer.

4. Representative Value Calculation Step (ST4) The representative value calculation means 29 analyzes the maximum absolute value f (x, y) image formed in the plane arrangement step, and calculates a representative value capable of evaluating the sharpness of the object image. This is the step of calculating. Representative values include a variance value, a contrast value, and an entropy value, and when any value is used,
An image with high definition can be selected from the maximum absolute value f (x, y) images formed for each propagation speed, and the propagation speed at that time can be known. Below, the maximum absolute value f
The variance value, contrast value, and entropy value of the image calculated from (x, y) will be described.

4-1. Dispersion value The dispersion value is represented by the following Equation 1.

[0048]

(Equation 1)

That is, it can be said that as the variance of the maximum absolute value f (x, y) is larger, the range of gradation is wider and the definition of the object image is higher.

4-2. FIG. 7 exemplarily shows a contrast value maximum absolute value f (x, y) image, and is apart from the point (x mark) of the amplitude value i of the maximum absolute value f (x, y) image by a displacement (r, θ). A co-occurrence matrix is created with the probability P (i, j) as an element where the amplitude value of the point (た) is j. Here, the number N of pairs of the positions of the crosses and the positions of the circles N
Is N = (Xsiz) when the above displacement is (1, 0 °).
e-1) × Ysize, and N = (Xsize-1) × (Ysize-1) when the displacement is (1,45 °), and N = Xsize when the displacement is (1,90 °). ×
(Ysize-1), and N = (Xsize-1) × (Ysize-1) when the displacement is (1,135 °). A co-occurrence matrix having P (i, j) as an element is represented as shown in FIG. The horizontal axis is the amplitude value i at the position of the mark x, and the vertical axis is the amplitude value j at the position of the mark 、. The value P (i, j) of each element (i, j) is i, j Represents the occurrence probability of the pair Difference k = ij between amplitude values in a pair
Then, the greater the absolute value of k, the greater the difference between the amplitude values of adjacent pixels. Therefore, k (= ij)
If the occurrence probability P (i, j) of an element (i, j) having a large absolute value is large, it can be said that the contrast value of the object image is large. However, in the co-occurrence matrix, N is normalized such that the sum of the occurrence probabilities P (i, j) in each element becomes 1. Here, Equation 2 holds for the contrast value.

[0051]

(Equation 2)

That is, it can be said that the greater the contrast value of the maximum absolute value f (x, y), the higher the sharpness of the object image.

4-3. Entropy value The entropy value is expressed by the following equation (3).

[0054]

(Equation 3)

Since P (i, j) is the occurrence probability,
D (k) and S (h) are both less than 1, so
The right side of Equation 3 takes a positive value. Further, a large entropy value in Equation 3 means that the sum and difference of gradations in each pair take various values, and the values of the co-occurrence matrix are widely distributed. That is, the larger the entropy value, the higher the sharpness of the object image.

5. Propagation velocity selection step (ST5) This is a step in which the propagation velocity selection means 30 automatically selects the propagation velocity in the medium from each representative value for each propagation velocity obtained in the representative value calculation step. FIG. 9 is a graph showing a dispersion value, a contrast value, and an entropy value with respect to a relative dielectric constant. Here, assuming that the propagation velocity is v, the following Equation 4 is established.

[0057]

(Equation 4)

Here, ε is the dielectric constant of the medium, and μ is the magnetic permeability of the medium.

As is clear from FIG. 9, all the representative values take the maximum value when the relative dielectric constant is about 5. Further, FIG. 10A shows a plane image representing the maximum absolute value f (x, y) when the relative dielectric constant is 5, and FIG. 10B shows a three-dimensional image representing three-dimensional voxel data. . As is clear from FIGS. 10A and 10B, the sharpness of the object image is high. Therefore, the propagation speed obtained from the value of the relative dielectric constant at which the representative value calculated in the representative value calculation step is maximum is automatically determined to be the propagation speed of the medium, and the value is selected.

6. Displaying step (ST6) The display means 31 outputs the two-dimensional maximum absolute value f (x, x) at the propagation speed selected in the propagation speed selecting step.
y) or since the depth is obtained from the propagation velocity and the time t, the three-dimensional image (x, y,
This is a step of outputting the t) and displaying it on the display unit 23. As shown for verifying the validity of the propagation speed selection step, FIG. 10A is a plane image, and FIG.
(B) is a three-dimensional image. Specifically, when a general-purpose personal computer or the like is used as the computer, the display unit 31 is an image for displaying on the display unit 23 predetermined image data basically provided in the personal computer or the like. Since the depth is obtained from the two-dimensional maximum absolute value f (x, y) or the propagation speed and the time t at the selected propagation speed, the time axis t is displayed on the display means and the image display means. And a preprocessing means for outputting the considered three-dimensional image (x, y, t) as the image data. The image display means and the preprocessing means are realized by installing a program for causing the computer to function as those means in a main storage area of the computer and executing the program on the computer.

[Another Embodiment] Another embodiment will be described below.

<1> In the maximum absolute value extracting step,
When extracting the maximum absolute value for each propagation velocity in the direction of the reflection time t-axis for each position (x, y) on the surface of each medium, it is also preferable to exclude amplitude values outside the predetermined range of the reflection time t. It is a form of.

When extracting the maximum absolute value for each propagation velocity in the direction of the reflection time t-axis for each position (x, y) on the surface of each medium, the polarity of the amplitude value is either positive or negative. It is also preferable to target only voxels from the viewpoint of improving the S / N ratio.

<2> Although the variance value, the contrast value, and the entropy value are calculated as the representative values in the representative value calculation step, the present invention is not limited to these representative values. For example, statistical texture features such as a density histogram, a co-occurrence matrix, a difference statistic, a run-length matrix, and a power spectrum may be used as representative values.

<3> In the above embodiment, each of the three-dimensional voxel data generation step, the maximum absolute value extraction step, the plane arrangement step, the representative value calculation step, the propagation speed selection step, and the display step The three-dimensional voxel data generating means 25, the maximum absolute value extracting means 27, the plane arranging means 28, the representative value calculating means 2
9, the propagation speed selection means 30, and the display means 3
1 (the image display means and the pre-processing means) is composed of a program corresponding to the computer and each means executable on the computer, that is, a combination of general-purpose hardware and dedicated software. Alternatively, some of the units may be configured by dedicated hardware, or some of the functions of the units may be configured by dedicated hardware. The computer that can execute the program is not necessarily a single computer. That is, some programs may be executed using a special computer having an appropriate architecture for the processing.

<4> Next, a computer-readable recording medium according to the present invention will be described. As described above, in the three-dimensional voxel data display method according to the present invention, the computer is configured to execute the three-dimensional voxel data generation unit 25, the maximum absolute value extraction unit 27, the plane arrangement unit 28, and the representative value calculation unit 29. To be executed by a program for functioning as the propagation speed selection means 30 and the display means 31 (the image display means and the preprocessing means), the program must first be installed in a main storage area of the computer. Therefore, these pre-installed programs can be read by a computer-readable recording medium such as a CD-ROM.
ROM (compact disc read only)
y memory) or the like, and the program is installed in the main storage area via the recording medium in each computer functioning as a three-dimensional voxel data display device. Further, when the installation is performed via a computer network, each program before the installation can be read from a computer that functions as the three-dimensional voxel data display device on a storage medium (such as a hard disk device) on a predetermined server. May be stored.

Here, the recording medium includes the maximum absolute value extracting means 27, the plane arranging means 28, the representative value calculating means 29, the propagation speed selecting means 30, and the display means 31. At least a program for functioning as the preprocessing means needs to be stored. The three-dimensional voxel data generating means 2
5. As the image display unit of the display unit 31, an existing program or a unit provided as a basic function of the computer can be used. However, since these programs are not always installed in a general-purpose computer, some or all of these programs may be stored in the same storage medium.

Note that the storage medium does not necessarily need to be a physically single storage device. For example, a plurality of CD-ROMs
Alternatively, the programs may be distributed and arranged on a plurality of servers distributed on a computer network. After all, a necessary program can be installed in a main storage area of a computer functioning as the three-dimensional voxel data display device.

[Brief description of the drawings]

FIG. 1 is a block configuration diagram of a search device including a three-dimensional voxel data display device.

FIG. 2 is an explanatory diagram of waveforms of a transmission signal and a reception signal.

FIG. 3 is a functional block diagram of the data analysis device.

FIG. 4 is a flowchart illustrating a three-dimensional voxel data display method according to the present invention.

FIG. 5 is an explanatory diagram showing an embedding state of a place where the search data used in the three-dimensional voxel data display method of the present invention is collected.

FIG. 6 is a display image example of original three-dimensional voxel data generated by the three-dimensional voxel data display method of the present invention.

FIG. 7 is a diagram exemplarily showing a maximum absolute value image.

FIG. 8 is a diagram showing a co-occurrence matrix having an occurrence probability as an element.

FIG. 9 is a diagram showing each representative value with respect to the relative dielectric constant calculated by the three-dimensional voxel data display method of the present invention.

FIG. 10 is a display image example showing a processing result obtained by the three-dimensional voxel data display method of the present invention (relative permittivity in the ground is 5), (a) is a planar image, and (b) is three-dimensional. It is an image.

FIG. 11 is a display image example showing a processing result of the related art (relative permittivity in the ground is 3), (a) is a plane image, and (b) is
It is a three-dimensional image.

FIG. 12 is a display image example showing a processing result of the conventional technique (relative permittivity in the ground is 7), (a) is a plane image, and (b) is
It is a three-dimensional image.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 soil (medium) 2 object 3 three-dimensional exploration device 4 incident wave 5 reflected wave 10 transceiver 20 data analysis device 21 data processing unit 21a memory 22 input unit 23 display unit 24 external auxiliary storage unit 25 three-dimensional voxel data generation unit 27 Maximum absolute value extracting means 28 Planar arrangement means 29 Representative value calculating means 30 Propagation velocity selecting means 31 Display means 32 Buried pipe

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Daisuke Tanimoto 7-1 Kioicho, Chiyoda-ku, Tokyo F-Term within Sophia University 5B057 AA14 BA01 BA05 CB08 CB13 CB16 DA07 DA16 DB03 DB09 DC22 5B080 AA17 AA20 5C082 AA01 AA21 AA31 AA36 BA12 BA46 BB15 BB25 DA53 DA61 DA87 MM10 5J070 AB01 AC01 AD02 AE11 AH35 AK22 AL02 BG11

Claims (8)

[Claims] 1. A three-dimensional voxel data which is a function of a position (x, y) of a surface of a medium and a reflection time t, which is generated based on a reflection signal intensity of a wave signal emitted from the surface of the medium into the medium. A method of displaying (x, y, t), wherein migration processing or synthetic aperture processing is performed on the original three-dimensional voxel data including the reflection signal intensity for each of a plurality of arbitrarily set propagation velocities in a medium. Run,
Generating the three-dimensional voxel data for each propagation speed; and for the three-dimensional voxel data for each propagation speed,
A maximum absolute value extraction step of extracting a maximum absolute value of an amplitude value in the reflection time t-axis direction for each position (x, y) of the medium surface; and a position of the medium surface extracted in the maximum absolute value extraction step ( (x, y) arranging the maximum absolute value on a predetermined plane to form an image, and a representative value calculation for calculating a representative value for evaluating the sharpness of the image formed in the plane arranging step A propagation speed selection step of selecting an appropriate propagation speed from the plurality of propagation speeds based on the representative value calculated in the representative value calculation step; and the propagation speed selected in the propagation speed selection step Displaying the maximum absolute value or the three-dimensional voxel data for each position (x, y) on the surface of the medium, the method comprising the steps of: 2. In the maximum absolute value extracting step, when extracting the maximum absolute value for each position (x, y) of the medium surface, an amplitude value outside a predetermined range in the reflection time t-axis direction is extracted. The method according to claim 1, wherein the three-dimensional voxel data is excluded. 3. In the maximum absolute value extracting step, when the maximum absolute value is extracted for each position (x, y) on the surface of the medium, a voxel having a positive or negative polarity of the amplitude value is targeted. The method according to claim 1 or 2, wherein the extraction is performed as (3). 4. The three-dimensional voxel data display method according to claim 1, wherein the representative value is a variance value. 5. The three-dimensional voxel data display method according to claim 1, wherein the representative value is a contrast value. 6. The three-dimensional display voxel data display method according to claim 1, wherein the representative value is an entropy value. 7. A three-dimensional voxel data which is a function of a position (x, y) of the medium surface and a reflection time t generated based on a reflection signal intensity of a wave signal emitted from the medium surface into the medium. A display device of (x, y, t), wherein a migration process or a synthetic aperture process is performed on the original three-dimensional voxel data including the reflection signal intensity for each of a plurality of arbitrarily set propagation velocities in a medium. Run,
Three-dimensional voxel data generating means for generating the three-dimensional voxel data for each propagation speed; and for the three-dimensional voxel data for each propagation speed,
A maximum absolute value extracting means for extracting a maximum absolute value of an amplitude value in a reflection time t-axis direction for each position (x, y) of the medium surface; and a position of the medium surface extracted by the maximum absolute value extracting means ( (x, y) arranging the maximum absolute value on a predetermined plane to form an image; and a representative value calculation for calculating a representative value for evaluating the sharpness of the image formed by the plane arranging means. Means, a propagation speed selecting means for selecting an appropriate propagation speed from the plurality of propagation speeds based on the representative value calculated by the representative value calculating means, and the propagation speed selected by the propagation speed selecting means And a display unit for displaying the maximum absolute value or the three-dimensional voxel data for each position (x, y) of the medium surface corresponding to the above. 8. The three-dimensional voxel data display method according to claim 1, wherein the migration processing or the synthetic aperture processing is performed for each of a plurality of arbitrarily set propagation velocities in a medium, and for each of the propagation velocities. A program for causing one or two or more computers to execute processing for generating three-dimensional voxel data, and for each of the three-dimensional voxel data, the maximum absolute value extraction step, the plane arrangement step, and the representative value calculation A computer-readable recording medium which stores a program for causing the computer to execute a step for each of the propagation speeds, and a program for causing the computer to execute the propagation speed selecting step and the displaying step.