Three-dimensional questing method, three-dimensional voxel data displaying method, and device therefor

• US 6,573,855 B1
• Filed: 05/31/2001
• Issued: 06/03/2003
• Est. Priority Date: 08/31/1998
• Status: Expired due to Fees

• Current Assignee: Osaka Gas Company Limited
• Original Assignee: Osaka Gas Company Limited
• Inventors: Takesue, Yasuhiro, Hayakawa, Hideki, Kawanaka, Akira
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US09/763,939
• Time in Patent Office: 733 Days
• Field of Search: 342/22, 342/25, 342/26, 342/175-186, 342/190-197, 342/27, 342/28, 367/14, 367/15, 367/25, 367/36, 367/37, 367/38, 367/68-73, 367/87, 367/88, 600/443, 702/18, 702/2-17
• US Class Current: 342/22
• CPC Class Codes: G01S 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12

Abstract

In a three-dimensional exploring method for finding location of a buried object by transmitting a wave signal (4) by means of e.g. an electromagnetic wave into the ground (1) and receiving the signal reflected from the object (2) in the course of movement over the ground surface and generating three-dimensional voxel data in the form of coordinates (x, y, t) consisting of a position (x, y) and a reflection time (t) based on intensity of the reflected signal, the method effects an object voxel selecting step of selecting one or more object voxels in accordance with a manual input operation; a binarizing step of extracting a candidate voxel group consisting of a plurality of voxels interconnected with each other and having amplitude values of positive or negative polarity and having magnitudes greater than a predetermined threshold; and a connecting/composing step of extracting, from the candidate voxel group extracted by the binarizing step, a connection-candidate voxel group to be connected to the object voxels selected by the object voxel selecting step and connecting said connection-candidate voxel group with said object voxels thereby to compose an object voxel group, whereby the location of the buried object (2) is detected at high S/N ratio. Further, when three-dimensional voxel data contains.a voxel deficient in data, the method effects, on said deficient voxel, a one-dimensional linear interpolation step of effecting a one-dimensional linear interpolation in a predetermined direction in an x-y plane including said deficient voxel, so that the deficient voxel can be interpolated easily.

Claims

1. In a three-dimensional exploring method for finding the location of an object present within a medium by sequentially effecting a transmitting/receiving step of transmitting a wave signal by means of an electromagnetic wave or sonic wave into the medium and receiving the signal reflected from the object within the medium in the course of movement over the surface of the medium and a three-dimensional voxel data generating step of generating three-dimensional voxel data in the form of coordinates (x, y, t) consisting of a position (x, y) on the medium surface and a reflection time (t) based on the intensity of the reflected signal;

the method comprising;

a maximum-magnitude extracting-step of extracting, from the three-dimensional voxel data generated by the three-dimensional voxel data generating step, a maximum value of the magnitude of the amplitude value and a reflection time t_MAX providing the maximum value in the direction of the reflection time (t) axis for the position (x, y) on the medium surface;

a plane-locating step of locating, respectively on an x-y plane of a predetermined reflection time (t), said maximum value and said reflection time t_MAX extracted by the maximum-magnitude extracting step;

an object-voxel selecting step at which said x-y plane having said maximum value located thereon is displayed and a coordinate point is designated on said displayed plane in accordance with a manual input operation, so that one or more object voxels are selected by specifying them with said designated coordinate point and said reflection time t_MAX associated therewith;

a binarizing step of extracting a candidate voxel group consisting of a plurality of voxels having amplitude values of positive or negative polarity and having magnitudes greater than a predetermined threshold and interconnected with each other; and

a connecting/composing step of extracting, from the candidate voxel group extracted by the binarizing step, a connection-candidate voxel group to be connected to the object voxels selected by the object voxel selecting step and connecting said connection-candidate voxel group with said object voxels thereby to compose an object voxel group.

2. The three-dimensional exploring method according to claim 1, wherein the predetermined threshold utilized by the binarizing step is set based on the amplitude value of the object voxel selected by the object voxel selecting step.

3. The three-dimensional exploring method according to claim 1, wherein at the object voxel selecting step, said one or more object voxels are selected by substituting, for said designated coordinate point, a coordinate point which is present adjacent said designated coordinate point and which has the same polarity as the designated coordinate point and an amplitude value of the maximum magnitude.

4. The three-dimensional exploring method according to claim 1, wherein the method effects a synthetic aperture operation or a migration operation on said three-dimensional voxel data or said candidate-voxel group or on said object voxel group.

5. The three-dimensional exploring method according to claim 1, wherein at said three-dimensional voxel data generating step, a Wiener filtering operation or an amplitude adjusting operation is effected on the three-dimensional voxel data in the direction of the reflection time (t) axis, and the source three-dimensional voxel data before the processing is replaced by the processed data.

6. A three-dimensional exploring apparatus for finding the location of an object present within a medium comprising:

transmitting/receiving means for transmitting a wave signal by means of an electromagnetic wave or sonic wave into the medium and receiving the signal reflected from the object within the medium in the course of movement over the surface of the medium and three-dimensional voxel data generating means for generating three-dimensional voxel data in the form of coordinates (x, y, t) consisting of a position (x, y) on the medium surface and a reflection time (t) based on the intensity of the reflected signal;

wherein the apparatus further comprises;

maximum-magnitude extracting means for extracting from said three-dimensional voxel data generated by the three-dimensional voxel data generating means, a maximum magnitude value of the amplitude value and a reflection time t_MAX providing the maximum value in the direction of the reflection time (t) axis for each position (x, y) on the medium surface;

plane-locating means for locating respectively, on a predetermined plane for each position (x, y) on the medium surface, said maximum magnitude value and said reflection time t_MAX extracted by said maximum-value extracting means;

an object-voxel selecting means for displaying said x-y plane having said maximum value located thereon and designating a coordinate point on said displayed plane in accordance with a manual input operation, so that one or more object voxels are selected by specifying them with said designated coordinate point and said reflection time t_MAX associated therewith;

binarizing means for extracting a candidate voxel group consisting of a plurality of voxels having amplitude values of positive or negative polarity and magnitudes greater than a predetermined threshold and interconnected with each other; and

connecting/composing means for extracting, from the candidate voxel group extracted by the binarizing means, a connection-candidate voxel group to b connected to the object voxels selected by the object-voxel selecting means and combining said connection-candidate voxel group with said object voxels thereby to compose an object voxel group.

7. In a three-dimensional exploring method for finding the location of an object present within a medium by sequentially effecting a transmitting/receiving step of transmitting a wave signal by means of an electromagnetic wave or sonic wave into the medium and receiving the signal reflected from the object within the medium in the course of movement over the surface of the medium and a three-dimensional voxel data generating step of generating three-dimensional voxel data in the form of coordinates (x, y, t) consisting of a position (x, y) on the medium surface and a reflection time (t) based on the intensity of the reflected signal;

wherein when the three-dimensional voxel data generated by the three-dimensional voxel data generating step contains a voxel deficient in data, the method effects, on said deficient voxel, a one-dimensional linear interpolation step of effecting a one-dimensional linear interpolation in a predetermined direction in an x-y plane including said deficient voxel when a distance along which the deficient voxels are present consecutively is shorter than a wavelength of the wave signal within said medium.

8. The three-dimensional exploring method according to claim 7, wherein said linear interpolation step is effected for two or more times with varying the direction of the one-dimensional linear interpolation.

9. A three-dimensional exploring apparatus for finding the location of an object present within a medium comprising:

transmitting/receiving means for transmitting a wave signal by means of an electromagnetic wave or sonic wave into the medium and receiving the signal reflected from the object within the medium in the course of movement over the surface of the medium and three-dimensional voxel data generating means for generating three-dimensional voxel data in the form of coordinates (x, y, t) consisting of a position (x, y) on the medium surface and a reflection time (t) based on the intensity of the reflected signal;

wherein the apparatus comprises linear interpolating means for effecting, when three-dimensional voxel data generated by three-dimensional voxel data generating means contains a voxel deficient in data, on said deficient voxel, a one-dimensional linear interpolation in a predetermined direction in an x-y plane including said deficient voxel when a distance along which the deficient voxels are present consecutively is shorter then a wavelength of the wave signal within said medium.

10. In a method of displaying three-dimensional voxel data generated in the form of coordinates (x, y, t) consisting of a position (x, y) on a medium surface and a reflection time (t) based on the intensity of a reflected signal of a wave signal transmitted from the medium surface into the medium and reflected therefrom;

the method executes;

for said three-dimensional voxel data, a maximum-magnitude extracting step of extracting a maximum magnitude value of the amplitude value in the direction of the reflection time (t) axis for each position (x, y) on the medium surface, a plane-locating step of locating said maximum magnitude value on a predetermined plane for each position (x, y) on the medium surface extracted by said maximum-value extracting step, and a plane displaying step of displaying said maximum magnitude value located on said predetermined plane.

11. The three-dimensional voxel data displaying method according to claim 10, wherein a maximum value and a minimum value are obtained from the maximum magnitude values extracted at said maximum magnitude extracting step and the maximum value and said minimum value respectively become an upper limit and a lower limit of the display scale.

12. The three-dimensional voxel data displaying method according to claim 10, wherein at said maximum magnitude extracting step for extracting the maximum magnitude values for each position (x, y) on the medium surface, a reflection time t_MAX providing the maximum magnitude values is also extracted.

13. The three-dimensional voxel data displaying method according to claim 10, wherein at the maximum magnitude extracting step for extracting maximum magnitude values of the amplitude value in the direction of the reflection time (t) axis for each position (x, y) on the medium surface, any amplitude values within a predetermined range of reflection time (t) are excluded.

14. The three-dimensional voxel data displaying method according to claim 10, wherein at the maximum magnitude extracting step for extracting the maximum magnitude values of the amplitude values in the direction of the reflection time (t) axis for each position (x, y) on the medium surface, only either voxels whose amplitude value polarity is positive or negative are used for the extracting step.

15. The three-dimensional voxel data displaying method according to claim 10, wherein prior to the maximum magnitude extracting step, a synthetic aperture operation or a migration operation is effected on three-dimensional voxel data consisting of the reflected signal intensity so as to generate said three-dimensional voxel data to be displayed.

16. The three-dimensional voxel data displaying method according to claim 15, wherein said synthetic aperture operation or migration operation is effected at various propagation velocities in various kinds of medium to generate a set of the three-dimensional voxel data for each of the propagation velocities, with said maximum magnitude extracting step and said plane locating step effected for each set of three-dimensional voxel data associated with each propagation velocity, and a processing result at an appropriate propagation velocity is selected based on the displayed results of the sets of three-dimensional voxel data at said plane displaying step for each propagation velocity.

17. An apparatus for displaying three-dimensional voxel data generated in the form of coordinates (x, y, t) consisting of a position (x, y) on a surface of a medium and a reflection time (t) based on the intensity of a reflected signal of a wave signal transmitted from the medium surface into the medium and reflected therefrom;

wherein the apparatus comprises;

maximum-magnitude extracting means for extracting from said three-dimensional voxel data, a maximum magnitude value of the amplitude value in the direction of the reflection time (t) axis for each position (x, y) on the medium surface;

plane-locating means for locating said maximum magnitude value on a predetermined plane for each position (x, y) on the medium surface extracted by said maximum-value extracting means; and

plane displaying means for displaying said maximum value located on said predetermined plane.