Description

RTM imaging post processing applies a suite of post-migration image enhancement filters to a depth-domain RTM stack produced by the RTM imaging module. The module accepts the depth image and optionally a time image and applies topographic cropping, a Laplacian filter to suppress low-wavenumber migration noise, an optional Laguerre-Gauss filter for additional image shaping, a frequency-frequency (f-f) filter, a constant phase rotation, and amplitude normalisation. These steps collectively improve the reflector sharpness and suppress the imaging artefacts that are characteristic of RTM outputs before the image is used for interpretation or velocity model building.

Input data

Input DataItem

Container for the standard input data connections. Connect this to the output of the preceding module in the processing sequence.

Input SEG-Y data handle

The SEG-Y file handle for the input depth-domain RTM image. Connect this to the corresponding output from the RTM imaging module or another depth imaging module.

Input trace headers

The trace header vector providing geometry and sorting information for the input image. Connect alongside the Input SEG-Y data handle.

Input gather

The depth-domain RTM image as a gather for use in workflow configurations where the RTM output is passed as a gather rather than a SEG-Y file.

Input stack line

Optional connection for 2D line geometry defining the processing line for crooked-line or 2D survey configurations.

Input crooked line

Optional crooked-line geometry for 2D surveys with irregular surface paths.

Input bin grid

The 3D bin grid definition for the survey. Required for 3D data to correctly map trace positions to inline and crossline bin coordinates during processing.

Input sorted headers

The sorted index vector used to control the order in which depth-domain gathers are read and processed within the sequence.

Parameters

Crop by topo

When enabled (default: true), zero-fills or removes image samples above the topographic surface at each lateral position. This prevents spurious energy appearing above ground level in areas of strong topographic relief.

Laplas filter

When enabled (default: true), applies a Laplacian filter to the depth-domain image to suppress the low-wavenumber (smooth, background) artefacts that are characteristic of the RTM imaging condition. The Laplacian filter enhances reflector sharpness by amplifying high-wavenumber image content, effectively acting as a high-pass spatial filter. This step is almost always recommended for RTM images.

Laguerre gauss filter

When enabled (default: false), applies an additional Laguerre-Gauss spatial filter to the image as an alternative or complement to the Laplacian filter. This filter provides a different frequency-wavenumber shaping response and can improve image quality on data with complex velocity contrasts. The weighting between the Laguerre-Gauss response and the unfiltered image is controlled by Laguerre weight.

Laguerre weight

The weighting factor for the Laguerre-Gauss filter contribution. The default is 1. Values closer to 1 apply full Laguerre-Gauss shaping; values closer to 0 reduce its influence. This parameter only affects the image when Laguerre gauss filter is enabled.

Diff output

When enabled (default: false), the module outputs a difference gather showing the change between the input image and the post-processed output. Use this during parameter testing to visualise the effect of each filter step.

Use ff filter

When enabled (default: true), applies an f-f (frequency-frequency) filter to suppress low-frequency migration noise in the depth-domain image. The strength of this filter is controlled by FF power.

FF power

The exponent controlling the strength of the f-f filter. The default is 1. Higher values apply stronger suppression of low-frequency image components. Only relevant when Use ff filter is enabled.

Shift phase angle

A constant phase rotation (in degrees) applied to the image after all spatial filter steps. The default is 0. Use this to correct for a known residual phase error or to adjust the reflector polarity convention.

Normalize amplitudes

When enabled (default: true), normalises the output image amplitudes to compensate for depth-dependent energy variations. Disable this only when preserving the absolute amplitude scaling from the imaging condition is required, for example in amplitude-versus-depth studies.

Settings

Auto-connection

When enabled (default: true), the output is automatically connected to the next module in the workflow. Uncheck to manually control data routing.

Bad data values option { Fix, Notify, Continue }

Controls behaviour when NaN or infinity values are detected in the input data. Notify halts execution and reports the location of bad values. Fix replaces bad values with zero and continues. Continue proceeds without fixing bad values. Use Notify during testing; switch to Fix or Continue for production runs.

Calculate difference

When enabled, produces a separate difference output gather showing the pixel-by-pixel difference between the input and post-processed image. Useful for evaluating the combined effect of all enabled filters.

Execute on { CPU, GPU }

Selects CPU or GPU execution for the post-processing filters. GPU execution accelerates the spatial filtering steps on large 3D depth images.

Distributed execution

Options for distributing the post-processing across multiple compute nodes.

Bulk size

The number of depth gathers processed per chunk in distributed mode.

Limit number of threads on nodes

The maximum number of CPU threads per compute node in distributed execution mode.

Job suffix

A text suffix appended to the distributed job name to distinguish concurrent runs.

Set custom affinity

When enabled, applies a custom CPU affinity mask to pin processing threads to specific cores or sockets.

Affinity

The CPU affinity mask applied when Set custom affinity is enabled.

Number of threads

The number of CPU threads used for parallel post-processing. The default uses all available logical cores.

Skip

When enabled, bypasses this module, passing the input image through unchanged. Use this to test downstream modules without applying post-processing.

Output data

Output DataItem

Container for the standard output data connections. Connect to the input of the next module in the processing sequence.

Output SEG-Y data handle

The SEG-Y file handle for the post-processed depth-domain image. Connect to a Save SEG-Y module to write the final image to disk.

Output trace headers

The trace header vector for the post-processed image.

Output gather

The post-processed depth-domain image as a gather, for display and further processing.

Output stack line

The output stack line geometry, passed through for use in downstream modules.

Output crooked line

The output crooked-line geometry, passed through for 2D survey workflows.

Output bin grid

The output bin grid definition, passed through for 3D survey workflows.

Output sorted headers

The sorted index vector, passed through to subsequent modules in the processing sequence.

Gather of difference

The difference gather (input minus output) produced when Calculate difference is enabled. Connect to a display module to visualise the filter effect.

Depth output gather

The final post-processed depth-domain image gather, equivalent to the output gather but explicitly labelled for depth-domain workflows.

Depth input gather

The unmodified input depth gather, provided as a pass-through output for parallel display or comparison workflows.

Information

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