CN114814961A - Ground penetrating radar data accurate positioning method for high-precision terrain correction - Google Patents
Ground penetrating radar data accurate positioning method for high-precision terrain correction Download PDFInfo
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/12—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with electromagnetic waves
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- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
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- G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
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- G01S19/45—Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement
- G01S19/47—Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
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Abstract
The invention relates to a method for accurately positioning ground penetrating radar data by high-precision terrain correction. The method comprises the following steps: acquiring a high-precision digital elevation model of a detection area; acquiring underground three-dimensional imaging data of a detection area, and extracting a track plane coordinate; superposing the high-precision digital elevation model and the track plane coordinates to obtain track three-dimensional data; and correcting the underground three-dimensional imaging data according to the track three-dimensional data. The method has the advantages of high operation efficiency, small labor investment, high achievement precision and strong practicability; the detection track does not need to be set in advance to correct the terrain, so that the ground penetrating radar is more flexible and convenient to detect; and the ground penetrating radar can be used in a complex terrain environment, and the practicability of the ground penetrating radar is improved.
Description
Technical Field
The invention belongs to the technical field of surveying and mapping and underground detection, and particularly relates to a ground penetrating radar data accurate positioning method for high-precision terrain correction.
Background
Ground Penetrating Radar (Ground Penetrating Radar) is a non-destructive measurement technique that uses electromagnetic waves to locate objects or interfaces buried in a visually opaque substance or subsurface medium. Ground penetrating radar transmits a series of regular low-power electromagnetic energy sequences to the material or ground and receives and detects weak reflected signals of buried targets. The buried target may be a conductor, a dielectric, or a combination of both. The ground penetrating radar utilizes the transmitted electromagnetic wave to react to the change of the electromagnetic property of the shallow underground. The propagation velocity of electromagnetic waves is the main controlling factor for the generation of reflections, which is determined by the relative permittivity contrast (or inter-layer contrast) between the background material and the target. A typical ground penetrating radar apparatus is composed of a transmitting antenna and a receiving antenna, and electromagnetic waves generated by the transmitting antenna are transmitted into the ground and then reflected from an interface or scattered from a point source. This reflected/scattered energy is then transmitted back to the earth's surface where it is recorded by the receiving antenna. There are now many devices that are commercially available, and the range and capabilities of this technology are evolving. Ground penetrating radars have also been successfully used to provide forensic information during criminal investigations, detect buried mines, survey roads, detect utilities, measure geophysical formations and other fields.
However, the ground penetrating radar also has technical defects in actual detection, and is susceptible to factors such as data acquisition area conditions (terrain, soil properties, electromagnetic field interference and the like), system configuration and measurement modes during data acquisition, so that interference waves on radar images are more, and the difficulty of target information identification and interpretation on the radar images is increased to different degrees. A three-dimensional laser mobile scanning system is introduced to obtain ground three-dimensional laser point cloud, and the abundant spatial information such as spatial structure, morphological characteristics, spectral characteristics and the like in the ground three-dimensional laser point cloud can be fully utilized, so that the positioning precision and the quantitative identification accuracy of the fault ground penetrating radar signal are integrally improved.
Disclosure of Invention
The invention aims to overcome the defects in the existing ground penetrating radar technology and provide a ground penetrating radar data accurate positioning method with high-precision terrain correction. And a three-dimensional laser mobile scanning system is used for obtaining a high-precision digital elevation model of the detection area, and then the underground three-dimensional imaging data of the ground penetrating radar is corrected according to the ground high-precision digital elevation model, so that the high-precision positioning of the ground penetrating radar data is realized, and the accuracy of image interpretation of the ground penetrating radar is improved.
The purpose of the invention is realized as follows:
a method for accurately positioning ground penetrating radar data of high-precision terrain correction is characterized by comprising the following steps: the method comprises the following steps:
acquiring a high-precision digital elevation model of a detection area;
acquiring underground three-dimensional imaging data of a detection area, and extracting a track plane coordinate;
superposing the high-precision digital elevation model and the track plane coordinates to obtain track three-dimensional data;
and correcting the underground three-dimensional imaging data according to the track three-dimensional data.
In the method for accurately positioning the ground penetrating radar data through high-precision terrain correction, a three-dimensional laser mobile scanning system is adopted to obtain a high-precision digital elevation model of a detection area, and the method specifically comprises the following steps:
acquiring initial point cloud data of a detection area;
filtering the initial point cloud data to obtain final ground points;
and (4) constructing a triangulation network according to the final ground point interpolation, and generating a high-precision digital elevation model of the detection area.
In the method for accurately positioning ground penetrating radar data with high-precision terrain correction, the step of acquiring initial point cloud data of a detection area specifically comprises
Synchronous static observation is carried out by using a plurality of GNSS receivers to obtain a control point of a survey area, and a relatively independent coordinate system is established in a region to be detected;
GNSS data, inertial data and laser data are synchronously recorded, and platform position and attitude information is obtained through close coupling calculation.
And carrying out registration, splicing, noise reduction and point cloud data fusion processing on the acquired original data to obtain initial point cloud data.
According to the method for accurately positioning the ground penetrating radar data with high-precision terrain correction, the ground slope threshold value and the like are set according to the reflection intensity, the echo times and the shape characteristics of different ground surface objects to carry out automatic iterative calculation until a reasonable ground point is calculated.
In the method for accurately positioning the ground penetrating radar data with high-precision terrain correction, the step of acquiring the underground three-dimensional imaging data of the detection area comprises the following substeps:
before collection, the three-dimensional ground penetrating radar system is subjected to distance measuring wheel correction, and inter-track distance, sampling depth, sampling frequency, trigger mode and GPS baud rate detection parameters are set.
During collection, a GNSS reference station is erected in a detection area for continuous tracking observation, the three-dimensional ground penetrating radar system collects underground three-dimensional imaging data line by line, high-frequency electromagnetic waves are transmitted to a ground structure through the transmitting antenna, and the reflected electromagnetic waves are received by the receiving antenna to generate channel data. And performing post-processing on data of a GNSS receiver and a GNSS base station carried by the ground penetrating radar system to obtain coordinates and time for data acquisition.
In the method for accurately positioning the ground penetrating radar data with high-precision terrain correction, the specific steps of extracting the track plane coordinates comprise:
and calculating a plane coordinate based on the wheel travel by using the minimum distance measurement unit of the ground penetrating radar distance measurement wheel and the data acquisition step distance, namely the plane coordinate of the ground penetrating radar track.
And according to the time synchronization information of the data, extracting effective GNSS data with the same time as the ground penetrating radar from the GNSS data, namely the ground penetrating radar track plane coordinate.
In the method for accurately positioning the ground penetrating radar data with high-precision terrain correction, the high-precision digital elevation model and the track plane coordinate are superposed, namely the elevation and attitude assignment of the ground penetrating radar data track is carried out to obtain track three-dimensional data, and the following steps are adopted:
and matching according to the plane coordinates of the ground penetrating radar track and the position information of the digital elevation model, and overlapping the ground penetrating radar track and the high-precision digital elevation model. And calculating the elevation of the ground penetrating radar running track by utilizing linear interpolation so as to obtain the three-dimensional coordinate of the ground penetrating radar track. And respectively obtaining gradient information along the advancing direction, the vertical direction and the lateral direction based on the digital elevation model so as to obtain three-dimensional attitude data of the ground penetrating radar track.
In the method for accurately positioning the data of the ground penetrating radar with high-precision terrain correction, the three-dimensional ground penetrating radar data terrain correction is realized by the following method:
and performing concussion-removing filtering, time zero correction, signal gain, background denoising, band-pass filtering, data smoothing and data cutting processing on the ground penetrating radar original data.
The distance between the electromagnetic wave on the standard reference surface and the ground surface is converted into the propagation time by adopting the time displacement principle, so that the uniform propagation time from the detection point to the standard reference surface is obtained, and the terrain correction of the ground penetrating radar data is realized.
The conversion of the propagation time and the propagation distance of the electromagnetic wave is the basic measurement principle of the ground penetrating radar, and the translation transformation of radar data in the depth direction is carried out by using a terrain surface to replace a uniform standard reference surface.
And combining the data of the multi-channel multi-track ground penetrating radar, performing spatial interpolation, and generating three-dimensional underground image data with terrain correction.
Compared with the prior art, the invention has the following advantages: 1) the invention utilizes the three-dimensional laser mobile scanning system to accurately position and obtain the high-precision digital elevation model. The addition of the IMU and the laser scanner avoids the problem of poor GNSS positioning signals caused by reasons such as ground object shielding. The work efficiency is high, and artifical the input is little, and the achievement precision is high, and the practicality is strong. 2) According to the method, the GNSS device in the ground penetrating radar system is used for acquiring the plane coordinates of the ground penetrating radar track, and then the superposition correction is carried out according to the coordinates and the digital elevation model, so that the detection track does not need to be set in advance for terrain correction, and the ground penetrating radar is more flexible and convenient to detect. 3) According to the method, the high-precision DEM constructed by the laser point cloud is used for correcting the terrain of the three-dimensional ground penetrating radar image, so that the distortion of ground fluctuation to the ground penetrating radar image is eliminated, the accuracy of image interpretation of the ground penetrating radar is improved, the ground penetrating radar can be used in a complex terrain environment, and the practicability of the ground penetrating radar is improved.
Drawings
FIG. 1 is a flow chart of a precise positioning of high-precision terrain corrected ground penetrating radar data.
Detailed Description
The present invention will be further illustrated by the following specific examples, which are carried out in the light of the technical solutions of the present invention, and it should be understood that these examples are only for illustrating the present invention and are not intended to limit the scope of the present invention.
The method for accurately positioning the data of the high-precision terrain correction ground penetrating radar mainly comprises the following steps:
1) a relatively independent coordinate system is established in the area to be detected, in the example, the coordinate system adopts a WGS84 coordinate system synchronous with GNSS, a 3-degree band is adopted, a central meridian is 114-degree 00', and a projection surface is an average elevation surface of a 23m measuring area, so that the accuracy of data result is ensured.
2) The GNSS/IMU resolving method adopts the GNSS/IMU pseudo range and pseudo range rate tight coupling technology to carry out POS resolving,
x 1 ＝(R N +H)cosLcosλ
y 1 ＝(R N +H)cosLsinλ
z 1 ＝[R N (1-f) 2 +H]sinL
wherein L, lambda and H are respectively latitude, longitude and height R of the carrier N F is curvature radius of each point on the prime circle and reference ellipsoid flat rate, x 1 、y 1 、z 1 Coordinates of 3 axes of the GNSS/IMU system, respectively.
3) The three-dimensional ground penetrating radar system acquires underground three-dimensional imaging data of a detection area, and sets detection parameters of the three-dimensional ground penetrating radar according to actual conditions, wherein the specific set parameters comprise:
the track pitch, which should be equal to or less than the channel spacing, is set to 0.05m in the example.
And secondly, setting the sampling depth according to the depth of the actual object to be detected, wherein the sampling depth is set to be 10m in the example.
③ trigger source, the example selects wheel as trigger source.
4) In order to ensure the precision of the digital elevation model and simultaneously consider the later-period calculation and the data utilization efficiency, the resolution of the digital elevation model is consistent with the numerical value of the data acquisition channel spacing of the ground penetrating radar, and the example is set to be 0.05 m.
5) The method specifically processes the original data of the ground penetrating radar:
firstly, vibration filtering is removed, various sample points of each channel of data are averaged, and direct current components and direct current offset caused by the previous channel of data are removed;
correcting time zero, removing the time of the electromagnetic wave propagating in the air layer, and correcting the actual propagation time of the electromagnetic wave of the ground penetrating radar in the dielectric body;
thirdly, signal gain is achieved, the Y direction is amplified according to the average amplitude attenuation curve of the electromagnetic wave signals, and the attenuation of the signals in the transmission process of the medium body is reduced;
background denoising, namely eliminating consistent noise in the whole section by selecting channels, and inhibiting energy with consistent level;
band-pass filtering, namely performing band-pass filtering on each channel of data by using recursive filtering through low-cut frequency and high-cut frequency corresponding to different frequency ground penetrating radar antennas;
and sixthly, smoothing the data, carrying out moving average on the data selected in each time period, and eliminating energy scattering of the data in the horizontal direction.
6) And (3) terrain correction of the ground penetrating radar data, wherein the elevation difference is calculated through an interpolation formula:
where h (x) is the height difference of the point relative to the reference plane, and v is the propagation speed of the electromagnetic wave in the air, and is generally 0.3 m/ns.
Claims (8)
1. A method for accurately positioning ground penetrating radar data of high-precision terrain correction is characterized by comprising the following steps: the method comprises the following steps:
acquiring a high-precision digital elevation model of a detection area;
acquiring underground three-dimensional imaging data of a detection area, and extracting a track plane coordinate;
superposing the high-precision digital elevation model and the track plane coordinates to obtain track three-dimensional data;
and correcting the underground three-dimensional imaging data according to the track three-dimensional data.
2. The method for accurately positioning the high-precision terrain-corrected ground penetrating radar data according to claim 1, characterized by comprising the following steps of: the method for acquiring the high-precision digital elevation model of the detection area by adopting the three-dimensional laser mobile scanning system specifically comprises the following steps:
acquiring initial point cloud data of a detection area;
filtering the initial point cloud data to obtain final ground points;
and (4) constructing a triangulation network according to the final ground point interpolation, and generating a high-precision digital elevation model of the detection area.
3. The method for accurately positioning the high-precision terrain-corrected ground penetrating radar data according to claim 1, characterized by comprising the following steps of: the method for acquiring the initial point cloud data of the detection area specifically comprises
Synchronous static observation is carried out by using a plurality of GNSS receivers to obtain a control point of a survey area, and a relatively independent coordinate system is established in a region to be detected;
synchronously recording GNSS data, inertial data and laser data, and obtaining platform position and attitude information through close coupling calculation;
and carrying out registration, splicing, noise reduction and point cloud data fusion processing on the acquired original data to obtain initial point cloud data.
4. The method for accurately positioning the high-precision terrain-corrected ground penetrating radar data according to claim 1, characterized by comprising the following steps of: and setting a ground slope threshold value and the like according to the reflection intensity, echo times and shape characteristics of different surface objects to perform automatic iterative calculation until a reasonable ground point is calculated.
5. The method for accurately positioning the high-precision terrain-corrected ground penetrating radar data according to claim 1, characterized by comprising the following steps of: the acquisition of the underground three-dimensional imaging data of the detection region comprises the following sub-steps:
before collection, a three-dimensional ground penetrating radar system is subjected to correction distance measurement wheel, and inter-road distance, sampling depth, sampling frequency, trigger mode and GPS baud rate detection parameters are set;
during collection, a GNSS reference station is erected in a detection area for continuous tracking observation, the three-dimensional ground penetrating radar system collects underground three-dimensional imaging data line by line, high-frequency electromagnetic waves are emitted to a ground structure through the emitting antenna, the reflected electromagnetic waves are received by the receiving antenna to generate channel data, data of a GNSS receiver and the GNSS base station carried by the ground penetrating radar system are subjected to post-processing, and coordinates and time of data collection are obtained.
6. The method for accurately positioning the high-precision terrain-corrected ground penetrating radar data according to claim 1, characterized by comprising the following steps of: the specific steps of extracting the track plane coordinates comprise:
calculating a plane coordinate based on a wheel travel by using the minimum distance measurement unit of the ground penetrating radar distance measurement wheel and the data acquisition step distance, namely the plane coordinate of the ground penetrating radar track;
and according to the time synchronization information of the data, extracting effective GNSS data with the same time as the ground penetrating radar from the GNSS data, namely the ground penetrating radar track plane coordinate.
7. The method for accurately positioning the high-precision terrain-corrected ground penetrating radar data according to claim 1, characterized by comprising the following steps of: superposing a high-precision digital elevation model and a track plane coordinate, namely assigning the elevation and the attitude of the ground penetrating radar data track to obtain track three-dimensional data, and adopting the following steps:
matching according to the plane coordinates of the ground penetrating radar track and the position information of the digital elevation model, overlapping the ground penetrating radar track and the high-precision digital elevation model, calculating the elevation of the ground penetrating radar running track by utilizing linear interpolation to obtain the three-dimensional coordinates of the ground penetrating radar track, and respectively obtaining gradient information along the advancing direction, the vertical direction and the lateral direction based on the digital elevation model to obtain the track three-dimensional data of the ground penetrating radar track.
8. The method for accurately positioning the high-precision terrain-corrected ground penetrating radar data according to claim 1, characterized by comprising the following steps of: the three-dimensional ground penetrating radar data terrain correction is realized by the following method:
performing concussion-removing filtering, time zero correction, signal gain, background denoising, band-pass filtering, data smoothing and data cutting processing on the ground penetrating radar original data;
converting the distance between the electromagnetic wave on the standard reference surface and the ground surface into the propagation time by adopting a time displacement principle, obtaining the uniform propagation time from the detection point to the standard reference surface, and realizing the terrain correction of the ground penetrating radar data;
and combining the data of the multi-channel multi-track ground penetrating radar, performing spatial interpolation, and generating three-dimensional underground image data with terrain correction.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115128609A (en) * | 2022-09-01 | 2022-09-30 | 中国科学院空天信息创新研究院 | Satellite-borne SAR three-dimensional product generation method and device |
| CN116819469A (en) * | 2023-08-28 | 2023-09-29 | 南京慧尔视智能科技有限公司 | Multi-radar target position synchronization method, device, equipment and storage medium |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115128609A (en) * | 2022-09-01 | 2022-09-30 | 中国科学院空天信息创新研究院 | Satellite-borne SAR three-dimensional product generation method and device |
| CN116819469A (en) * | 2023-08-28 | 2023-09-29 | 南京慧尔视智能科技有限公司 | Multi-radar target position synchronization method, device, equipment and storage medium |
| CN116819469B (en) * | 2023-08-28 | 2023-11-10 | 南京慧尔视智能科技有限公司 | Multi-radar target position synchronization method, device, equipment and storage medium |
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