GRADIX
Ground Penetrating Radar (GPR)
See also the newer Windows versionIXGPR
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GRADIX is a Ground PenetratingRadar processing and interpretation package for IBM 386, 486 and Pentium based compatiblemicrocomputers. 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, inmanufacturers' formats, as well as SEG-Y and SEG-2 and user-defined formats. GRADIX runsin 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. radar@sensoft.on.ca
and
Mala Geoscience, Skolgatan 11, S-930 70Mala Sweden. geoscience@malags.se
Image size and quality have been loweredto reduce download time
GRADIX was developed to provide the geophysicist with a tool toprocess and interpret his GPR data interactively on a PC. GRADIX provides 256-colorgraphical display of GPR data, at the maximum resolution allowed by the graphics hardware,and features animated parameter selection together with the most comprehensive GPRprocessing package available.
INPUT
GRADIX accepts GPR instrument files in the following proprietaryformats:
- GSSI .dzt files
- Pulse Ekko .dt1 files
- Mala .rd3 files
- GRADIX also accepts SEG-Y, SEG-2 and user-defined formats.
EXPORT
GRADIX can export profiles or resampled profiles to all formatssupported in the import section.
GEOMETRY
Profiles are located on the project map relative to their groundlocation. Multiple files can be combined into one profile.
TOPOGRAPHY SUPPORT
Full support for topography is included by means of aspreadsheet-like editor that features smoothing and interpolation. Column-based files canbe exported to form templates for topography editing in external packages. These files canthen be imported to add true topography to the profiles.
PROJECTS
GRADIX is a project based processing system; all data are importedfor a given project, and can then be selected and manipulated from a project map. Theprogram maintains a database for each project.
Display from GRADIX showing the project map,loaded lines and the version and history pop-up boxes for the selected line
All processing and editing steps create new versions of the selectedprofile. This allows users to undo incorrect processing, do comparative processing andstepwise processing. GRADIX also allows the user to go back in a processing sequence andre-select a previous version and reprocess the profile using different parameters.
Each version of a profile contains a complete History listing ofwhat was performed on the profile as well as a list of profile versions that the specificprofile stems from.
TRACE EDITING
Traces may be individually shifted, reversed, or killed. Subsets ofa profile may be created simply by dragging the mouse over the profile display. Traces maybe stacked.
DISPLAYS
Data display features are nearly unlimited. Traces are displayed inany combination of wiggle and color variable density display. The user has full controlover color scales (load, save and create), display gain, horizontal and vertical scale,and annotation.
Display includes full panning and zooming capabilities, and a secondprofile facility for instant, back-and-forth comparison of profiles.
Main profile view screen showing GPR profilein grayscale
Profile display also allows the user to select a second profile todisplay in comparison to the first. The display is toggled between the two displays.
Gradix MOVIE viewer
GRADIX also offers a "MOVIE" display option. This optionscrolls 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 verticaland horizontal scales as well as gain and color changes can be made.
Interactive color editor to set up userdefined color bars that can be saved
HARDCOPY
GRADIX offers an full color WYSIWYG print preview that allows you toset 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 ofplot file outputs.
GRADIX also features annotation of entries in the anomaly databasedirectly on hardcopy plots. User editable fields can be placed on the plots to markanomalies.
Plot Preview gives WYSIWYG display of hardcopy output. Page frame is indicated to help user with Auto scaling and interactive editingof plot elements. Display parameters can also be set from the plot preview
ANIMATION PANELS
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 theprocessing parameters. The results are displayed using an animation feature that"pages" through the results using a slider bar. This allows for fast comparisonof varying processing parameter results. Animation is available for:
- velocity analysis for CMP gathers
- filtering
- deconvolution
- 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 avelocity animation
INTERACTIVE PROCESSING
GRADIX features a number of interactive processing screens where thedata and processing operators are displayed on a graphical screen.
The user has the option of entering the operator parameters in dataentry fields or use the mouse to manipulate graphical entities that are synchronized withthe 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 interactiveprocessing 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 for traces
- remove background - background removal with a variety of options
- remove attenuation - frequency-dependent gain computation and application
- filter - a large variety of filtering options
- gain - a large variety of gain functions
Interactive filter design screen displayingfilter time series, amplitude and phase spectrum
All processing screens and pop-up dialog boxes have contextsensitive help buttons to explain the current function. The user has the option to scrollbackwards and forwards in the help system to previously viewed entries.
Interactive background removal screen
SPECTRAL ANALYSIS
Another aspect of interactive processing is spectral analysis.GRADIX offers one and two dimensional spectral analysis with the option to plot thespectra.
Spectral analysis is done by choosing a subset of the profile in aprofile view mode and then calculating the spectrum for the subsection. The FK Spectrumoption allows the user to define velocity or multiple polygon filters and then view thefiltered traces in comparison with the original selected portion of the profile.
FK Spectral analysis screen showing spectraand controls for specifying velocity or polygon filters
Screen showing pre- and post filtered tracesafter specifying a velocity filter in FK Analysis
VELOCITY ANALYSIS & DEPTH CONVERSION
In order to do a depth conversion the user defines a velocityprofile. A velocity profile is a 2d section of defined velocities with depth that matchthe current profile in terms of location, length or depth.
Interactive velocity profile setup screendisplaying project map, available velocity functions, GPR profile and velocity section
GRADIX stores all velocity information in a velocity database. Toconstruct a velocity profile, velocity records are extracted from the database and addedto the velocity profile.
Velocity records are obtained from fitting hyperbolas or linearfeatures, 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 fieldsand then the data are processed according to these parameters. Each non interactiveprocessing step also creates a new version of the profile.
- declip - reconstitute clipped traces
- despike - remove sample spikes
- spectral balance - time domain spectral balancing
- fk - fk filtering
- migration - fk migration
- fx decon - fx predictive filter for noise removal
- deconvolution - spiking and predictive deconvolution
- sum - different versions of a profile may be added or subtracted
- mix - trace mixing
- statics - elevation statics may be applied to correct for topography
INTERPRETATION
Various tools are supplied for the interpretation of the data.Velocity interpretation by means of interactive hyperbola or linear fitting (tell at aglance whether a diffractor is below or above ground) add velocity records to the Velocitydatabase that is used to construct velocity profiles.
Anomaly flagging involves point and click marking of anomalies fromon profile. These anomalies can then be commented and the entries are stored in a Anomalydatabase that is displayed in the project map or exported to a external file that containsthe time, depth, location and type of anomaly.
Project map showing profiles and"icons" indicating interpreted anomalies.
