Description

The Radon – TauP backward transform reconstructs seismic traces in the time-offset (t-x) domain from a Radon spectrum previously computed by the Radon – TauP module. This is the inverse (adjoint) step of the forward Radon transform: it takes the tau-p domain representation of a gather, optionally applies taper windows in the p and tau dimensions to isolate or reject a zone of events, and transforms the result back to the original trace geometry.

Use this module in a two-step demultiple or noise attenuation workflow: first apply the Radon – TauP forward transform to obtain the spectrum, then use this backward transform to reconstruct only the desired events (primaries or multiples). The transform type (parabolic, linear, Foster-Mosher hyperbolic) is read automatically from the spectrum and does not need to be set here. The reference offset is also inherited from the spectrum.

Input data

Input DataItem

The primary data connection carrying the seismic dataset. This item transports the SEG-Y file handle, trace headers, and geometry objects that are passed through to the output unchanged.

Input SEG-Y data handle

Reference to the SEG-Y file object associated with the input dataset. Passed through to the output.

Input trace headers

Trace header vector for the input seismic data. The headers define the source-receiver geometry of the output gather and are passed through unchanged.

Input gather

The original time-offset gather. The module uses the trace geometry (offsets and trace count) from this gather to construct the output data dimensions. The actual amplitude data from this input is not used in the backward transform — only the geometry metadata is required.

Input stack line

Stack line geometry item passed through from the input to the output.

Input crooked line

Crooked line geometry item passed through from the input to the output.

Input bin grid

Bin grid item passed through from the input to the output.

Input sorted headers

Sorted trace header index passed through from the input to the output.

Input spectrum

The Radon tau-p spectrum computed by the Radon – TauP forward transform module. This gather-shaped object stores one pseudo-trace per p-value; each pseudo-trace holds the tau-domain energy at that slowness. The spectrum encodes the transform type, p-value grid, reference offset, and number of expanded samples in its trace headers, which are all read automatically by the backward transform. Connect the Output spectrum item of the Radon – TauP module directly here.

Parameters

Reject tapers

Controls whether the P taper and Tau taper zones are used to reject (zero out) or preserve the energy within the defined zone. Default: disabled (preserve). When disabled, the taper window passes the enclosed energy to the output (use to reconstruct primaries or multiples from a specific p-zone). When enabled, the energy inside the taper window is attenuated and the energy outside is preserved (use to subtract a specific event type).

P tapers

Container group defining the curvature (p-value) taper zone applied to the Radon spectrum before the backward transform. The taper is a trapezoid defined by four p-values: P 1 (ramp-on start), P 2 (ramp-on end / flat-top start), P 3 (flat-top end / ramp-off start), and P 4 (ramp-off end). All values are in seconds (the same unit as the p-axis of the spectrum). Default values (±100 s) effectively disable the taper — set them to match the p-range of the event you want to isolate or reject.

Tau tapers

Container group defining the time (tau) taper zone applied to the Radon spectrum before the backward transform. The taper is a trapezoid defined by four tau values: Tau 1 (ramp-on start), Tau 2 (ramp-on end), Tau 3 (ramp-off start), and Tau 4 (ramp-off end). All values are in seconds. Default values (±100 s) effectively disable the taper.

Advance

Container group for advanced options. Contains the Ignore sorting flag (default: disabled). When enabled, the module accepts input gathers with any trace sorting order, without enforcing ascending-offset sorting. Enable this only when the input gather has a non-standard sort order.

Frequency min

Lower frequency limit of the backward transform pass-band, in Hz. Default: 0 Hz. Set this to match the lower usable signal frequency of the data. Should be consistent with the value used in the forward transform.

Frequency max

Upper frequency limit of the backward transform pass-band, in Hz. Default: 100 Hz. Set this to match the upper usable signal frequency of the data. Should be consistent with the value used in the forward transform.

Pre-Whitening Factor

Stabilisation factor for the least-squares inversion, as a percentage of the maximum spectral power. Default: 0.5 %. Increase this value if the backward transform produces numerical instabilities or ringing artefacts in the output gather.

Settings

Auto-connection

When enabled, the module automatically connects to adjacent modules in the processing flow.

Bad data values option { Fix, Notify, Continue }

Controls how corrupted (NaN) samples are handled. Fix replaces bad values before processing. Notify reports the problem and stops. Continue proceeds without correction.

Execute on { CPU, GPU }

Selects whether the Radon backward transform is executed on the CPU or GPU. GPU execution requires a compatible CUDA-capable graphics card and can significantly accelerate computation for large gathers.

Distributed execution

Options for distributing computation across multiple nodes in a cluster environment.

Bulk size

Minimum number of gathers to process in each distributed computation chunk.

Limit number of threads on nodes

Maximum number of CPU threads to use per distributed processing node.

Job suffix

Optional text suffix appended to the distributed job name for identification purposes.

Set custom affinity

When enabled, allows specifying a custom CPU core affinity mask for the processing threads.

Affinity

CPU affinity mask specifying which processor cores are used. Only active when Set custom affinity is enabled.

Number of threads

Number of CPU threads used for parallel computation. Set to the number of available physical cores for best performance.

Skip

When enabled, this module is bypassed and the input data passes through unchanged.

Output data

Output DataItem

The output data connection carrying the reconstructed seismic dataset.

Output SEG-Y data handle

The SEG-Y file handle passed through from the input.

Output trace headers

The trace headers passed through from the input, unchanged.

Output gather

The reconstructed time-offset gather produced by the backward Radon transform. The output has the same number of traces, sample rate, and trace length as the original input gather, with amplitudes reconstructed from the tau-p spectrum after applying the specified taper windows. Connect this gather to subsequent processing steps such as adaptive subtraction, stacking, or NMO correction removal.

Output stack line

The stack line geometry object passed through from the input.

Output crooked line

The crooked line geometry object passed through from the input.

Output bin grid

The bin grid object passed through from the input.

Output sorted headers

The sorted trace header index passed through from the input.

Information

Graphics

Custom actions

References

Hampson, D., 1986, Inverse velocity stacking for multiple elimination: Journal of the Canadian Society of Exploration Geophysicists, 22, 44-55.

Yilmaz, O., 1987, Seismic data processing: Society of Exploration Geophysicists.