General

GRADIX provides you with all the tools you need to read, edit, analyze, process, interpret, and output colour plots of GPR data to nearly any colour output device. GRADIX allows you to read GPR data from any instrument, 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 100Mb or larger hard disk.

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 package available.

Input

GRADIX accepts GPR instrument files from most manufacturers.

GRADIX also accepts SEG-Y, SEG-2 and user-defined formats.

Export

GRADIX can export profiles or re-sampled profiles to all formats supported in the import section.

Geometry

Profiles are located on the project map relative to their ground location. Multiple files can be combined into one profile.

Topography Support

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.

Projects

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 project.

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.

Trace Editing

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.

Displays

Data display features are nearly unlimited. Traces are displayed in any combination of wiggle and colour-variable density display. The user has full control over colour scales (load, save and create), display gain, horizontal and vertical scale, and annotation.

Display includes full pan and zoom capabilities and a second-profile facility for instant, back-and-forth comparison of profiles.

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.

Hard Copy

GRADIX offers a full colour WYSIWYG print preview that allows you to set plotting parameters interactively. You see the plot as it will appear on the paper.

Virtually all colour and monochrome hardcopy devices are supported, as well as a variety of plot-file outputs.

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 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
• filtering
• deconvolution
• fk filters
• migration velocity

Interactive Processing

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 using 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 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

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...

Spectral Analysis

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.

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.

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 balancing
• fk - fk filtering ú 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 ú statics - elevation statics may be applied to correct for topography

Interpretationnn

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 on the profile. These anomalies can then be commented and the entries are stored in an 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.

Standard Components

GRADIX v1 and instruction manual.