Correction
of the ground level on the GPR profile is required when, in the process of GPR
research, the GPR antennas were separated from the earth's surface. For
example, GPR antennas can be mounted on the external suspension of a drone or
car for road research. In the process of moving the GPR, the antennas of which
are mounted in this way, the distance between the antennas and the surface of
the research object will not be a constant value, but will fluctuate within
some limits.
The
picture below on the left shows a fragment of a GPR profile obtained during a
GPR survey using a drone. It can be noted that due to periodic small changes in
flight altitude, GPR pulses reach the earth's surface at different times. For
this reason, extended reflections on the radarogram are distorted in a sawtooth
manner. The figure on the right shows the result of applying the Surface Level
Correction option. The sawtooth distortions have disappeared on the radarogram,
the horizontally extending reflections have become smoother.
For a more
detailed description of this processing option, see the chapter Surface Level Correction on GPR Profile of the user manual for the GEORADAR-EXPERT software system, which is available
on the download page.
The
GEORADAR-EXPERT software system implements the conversion of the radarogram
picture from the graphic format to the efd GPR profile format. The need for
such a conversion may arise when the GPR profiling file is lost and there is
only an picture of this GPR profile in an article or report that exists in
electronic form or on paper. As a result of the conversion, the user is able to apply to the GPR
profile all digital signal processing options and all types of GPR data
analysis provided in GEORADAR-EXPERT.
Below is a
page of the document containing the radarogram picture and the main window of
the GEORADAR-EXPERT software system with the loaded GPR profile, which is the
result of converting the radarogram picture from this document.
If a
document containing a radarogram picture is on paper, the user scans a page
with this picture in high quality, cuts out the radarogram picture and saves it
in a graphic format. Next, the user converts this picture into a GPR profile
file using GEORADAR-EXPERT. If the document exists in electronic form, the user
cuts out the radarogram picture and converts it into a GPR profile file.
For a more detailed description of the conversion process, see the chapter Convert GPR Profile Picture to EFD Format to EFD format of the user manual for the GEORADAR-EXPERT software system, which is available on the download page.
Coordinates are extracted using a GPS data converter. The converter is designed to extract
coordinates from GPS data files, convert and save these coordinates in the gexyz format, gexyz files are used for positioning GPR data in the process of
creating a 3D assembly.
Source GPS
data files for coordinate extraction can be in txt, gps, csv, gpx and kml text
formats. In files with the txt, gps or csv extension, data should be arranged in columns, separated by
semicolons, colon or spaces. Coordinate values in files with the txt, gps or csv extension can
be written in the format of the universal transverse Mercator projection UTM or in degrees, as a decimal
fraction.
The gpx file must conform to the GPS eXchange Format for storing and
exchanging data. The kml file must
conform to the Keyhole Markup Language textual geodata format, kml files
are used to represent 3D geospatial data in Google Maps and Google Earth programs.
Also,
using a GPS data converter, the user can convert coordinates from gexyz format to kml format. This makes it possible to superimpose the position of
the GPR profiles on the terrain map in the Google
Maps and Google Earth programs.
For a more detailed description of working with the GPS data converter, see the chapter Creating XYZ Coordinate Table Using GPS Data Converter of the user manual for the GEORADAR-EXPERT software system, which is available on the download page.