Ground Penetrating Radar
GRADIX is a Ground Penetrating Radar
processing and interpretation package for IBM 386, 486 and Pentium based
compatible microcomputers. GRADIX provides you with all the tools you need
to read, edit, analyze, process, interpret, and output color plots of GPR
data to nearly any color output device. Gradix allows you to read GPR data
from most commercially available instruments, in manufacturers' formats, as
well as SEG-Y and SEG-2 and user-defined formats. GRADIX runs in protected
mode on 386, 486 and Pentium based machines with standard math coprocessor,
8Mb or more RAM and 100 Mb or larger hard disk.
Radar data courtesy of Sensors &
Software, Inc. 1091 Brevik Pl. Mississauga, Ontario, Canada L4W 3R7. firstname.lastname@example.org
Mala Geoscience, Skolgatan 11, S-930 70
Mala Sweden. email@example.com
Image size and quality have been lowered
to reduce download time
GRADIX was developed to provide the
geophysicist with a tool to process and interpret his GPR data interactively
on a PC. GRADIX provides 256-color graphical display of GPR data, at the
maximum resolution allowed by the graphics hardware, and features animated
parameter selection together with the most comprehensive GPR processing
GRADIX accepts GPR instrument files in the
following proprietary formats:
- GSSI .dzt files
- Pulse Ekko .dt1 files
- Mala .rd3 files
- GRADIX also accepts SEG-Y, SEG-2 and
GRADIX can export profiles or resampled
profiles to all formats supported in the import section.
Profiles are located on the project map
relative to their ground location. Multiple files can be combined into one
Full support for topography is included by
means of a spreadsheet-like editor that features smoothing and interpolation.
Column-based files can be exported to form templates for topography editing
in external packages. These files can then be imported to add true
topography to the profiles.
GRADIX is a project based processing system;
all data are imported for a given project, and can then be selected and
manipulated from a project map. The program maintains a database for each
Display from GRADIX showing the project
map, loaded lines and the version and history pop-up boxes for the selected
All processing and editing steps create new
versions of the selected profile. This allows users to undo incorrect
processing, do comparative processing and stepwise processing. GRADIX also
allows the user to go back in a processing sequence and re-select a previous
version and reprocess the profile using different parameters.
Each version of a profile contains a
complete History listing of what was performed on the profile as well as a
list of profile versions that the specific profile stems from.
Traces may be individually shifted, reversed,
or killed. Subsets of a profile may be created simply by dragging the mouse
over the profile display. Traces may be stacked.
Data display features are nearly unlimited.
Traces are displayed in any combination of wiggle and color variable density
display. The user has full control over color scales (load, save and create),
display gain, horizontal and vertical scale, and annotation.
Display includes full panning and zooming
capabilities, and a second profile facility for instant, back-and-forth
comparison of profiles.
Main profile view screen showing GPR
profile in grayscale
Profile display also allows the user to
select a second profile to display in comparison to the first. The display
is toggled between the two displays.
Gradix MOVIE viewer
GRADIX also offers a "MOVIE" display option.
This option scrolls the profile on the screen in a continuous mode. Controls
exist for fast forward, rewind and pause. Movie view is only available for
variable density displays but vertical and horizontal scales as well as gain
and color changes can be made.
Interactive color editor to set up user
defined color bars that can be saved
GRADIX offers an full color WYSIWYG print
preview that allows you to set plotting parameters interactively. You see
the plot as it will appear on the paper. Virtually all color and monochrome
hardcopy devices are supported, as well as a variety of plot file outputs.
GRADIX also features annotation of entries
in the anomaly database directly on hardcopy plots. User editable fields can
be placed on the plots to mark anomalies.
Plot Preview gives WYSIWYG display of
hard copy output. Page frame is indicated to help user with Auto scaling and
interactive editing of plot elements. Display parameters can also be set
from the plot preview
Animated panels allow the user to select a
subsection of the data, perform the desired processing on the subsection for
a user-defined range of the processing parameters. The results are displayed
using an animation feature that "pages" through the results using a slider
bar. This allows for fast comparison of varying processing parameter results.
Animation is available for:
- velocity analysis for CMP gathers
- fk filters
- migration velocity
Animated velocity panel showing CMP
gather, slider bar and semblance curve. Click on the image to download an
AVI movie that shows a velocity animation
GRADIX features a number of interactive
processing screens where the data and processing operators are displayed on
a graphical screen.
The user has the option of entering the
operator parameters in data entry fields or use the mouse to manipulate
graphical entities that are synchronized with the data entry fields. Once
the desired operator is chosen the processing is carried out. All processing
steps create a new version of the profile. The following interactive
processing can be performed:
- dewow - remove instrument wow
- drift removal - flatten data on first
arrivals (remove instrument drift)
- set time zero - pick and set time zero
- remove background - background removal
with a variety of options
- remove attenuation - frequency-dependent
gain computation and application
- filter - a large variety of filtering
- gain - a large variety of gain functions
Interactive filter design screen
displaying filter time series, amplitude and phase spectrum
All processing screens and pop-up dialog
boxes have context sensitive help buttons to explain the current function.
The user has the option to scroll backwards and forwards in the help system
to previously viewed entries.
Interactive background removal screen
Another aspect of interactive processing is
spectral analysis. GRADIX offers one and two dimensional spectral analysis
with the option to plot the spectra.
Spectral analysis is done by choosing a
subset of the profile in a profile view mode and then calculating the
spectrum for the subsection. The FK Spectrum option allows the user to
define velocity or multiple polygon filters and then view the filtered
traces in comparison with the original selected portion of the profile.
FK Spectral analysis screen showing
spectra and controls for specifying velocity or polygon filters
Screen showing pre- and post filtered
traces after specifying a velocity filter in FK Analysis
VELOCITY ANALYSIS & DEPTH CONVERSION
In order to do a depth conversion the user
defines a velocity profile. A velocity profile is a 2d section of defined
velocities with depth that match the current profile in terms of location,
length or depth.
Interactive velocity profile setup screen
displaying project map, available velocity functions, GPR profile and
GRADIX stores all velocity information in a
velocity database. To construct a velocity profile, velocity records are
extracted from the database and added to the velocity profile.
Velocity records are obtained from fitting
hyperbolas or linear features, user defined records and CMP analysis using
the animated panels.
NON INTERACTIVE PROCESSING
Gradix also allows for non interactive data
processing of profiles. This processing requires the user to define the
processing parameters in data entry fields and then the data are processed
according to these parameters. Each non interactive processing step also
creates a new version of the profile.
- declip - reconstitute clipped traces
- despike - remove sample spikes
- spectral balance - time domain spectral
- fk - fk filtering
- migration - fk migration
- fx decon - fx predictive filter for noise
- deconvolution - spiking and predictive
- sum - different versions of a profile may
be added or subtracted
- mix - trace mixing
- statics - elevation statics may be
applied to correct for topography
Various tools are supplied for the
interpretation of the data. Velocity interpretation by means of interactive
hyperbola or linear fitting (tell at a glance whether a diffractor is below
or above ground) add velocity records to the Velocity database that is used
to construct velocity profiles.
Anomaly flagging involves point and click
marking of anomalies from on profile. These anomalies can then be commented
and the entries are stored in a Anomaly database that is displayed in the
project map or exported to a external file that contains the time, depth,
location and type of anomaly.
Project map showing profiles and "icons"
indicating interpreted anomalies.