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Slopes to gather converts a set of tomographic slope layers — dip-angle picks derived from the common-offset or common-midpoint domain — into synthetic seismic gathers in time, depth, or frequency domain. For each input bin, the module interpolates the slope attributes from the surrounding tomo slope layer data using Kriging, then assembles the interpolated values into gather traces suitable for input to subsequent depth imaging or velocity analysis modules.
This module is used in diffraction and stereo tomography workflows to bridge the gap between the tomo slope picking step and the gather-based velocity updating step. The output gathers carry inline and crossline slope values as trace amplitude, and can be displayed in the Graphics panel to verify the quality of the slope interpolation before proceeding to tomographic inversion.
A bin point vector item defining the output bin grid — the set of CMP or image point locations at which slope gather traces will be generated. Connect the output of a binning or geometry module.
A tomo slope layers item containing the dip-angle picks (inline and crossline slopes) extracted from the seismic data. This is the primary data input produced by the slope picking module that precedes this step in the workflow.
Vertical sample interval (s) of the output gather traces. Default: 0.004 s (4 ms). Set this to match the sample rate of the original seismic data to ensure consistent trace length and avoid resampling artefacts in downstream modules.
Total length (s) of each output gather trace. Default: 5 s. Set this to cover the full two-way time range of interest. The number of samples in each output trace equals Output data length / Sample interval.
Reference velocity (m/s) used to convert slope values from the time domain to the depth domain when Gather domain is set to TIME. Default: 2000 m/s. This parameter is only active when the output domain is TIME. Use a velocity representative of the average shallow-to-mid section velocity.
Maximum search radius (m) within which neighbouring tomo slope data points are considered when interpolating the slope value at each output bin. Default: 1000 m. Bins with no tomo slope data within this radius will receive a zero or null slope value. Increase for sparse picking coverage; reduce to avoid smearing across geological boundaries.
Distance threshold (m) below which a tomo slope pick is considered to coincide with an output bin and is copied directly without interpolation. Default: 5 m. Set this to approximately half the bin spacing of the input tomo data.
Parameters controlling the Kriging interpolation used to fill the slope values from picking locations onto the full output bin grid.
Spatial covariance model used by the Kriging interpolator. Default: Exponential. Exponential gives a sharper decay with distance and is well suited to data with abrupt lateral changes. Spherical is a standard semivariogram model commonly used in geostatistics. Gaussian produces the smoothest interpolation and is appropriate when slope values are expected to vary continuously.
Correlation range (m) of the Kriging covariance model — the distance beyond which data points have negligible influence on the interpolated value. Default: 100000 m. A large default range effectively produces a smooth, long-wavelength interpolation. Reduce to match the actual spatial correlation length of the dip picks in your data.
Maximum number of neighbouring data points used to estimate the Kriging weights at each output bin. Default: 20. Increasing this improves interpolation accuracy at the cost of longer processing time; values between 10 and 30 are typical.
Domain of the output gather traces. Default: TIME. TIME outputs slope values on the two-way time axis with depth-to-time conversion applied using Time to depth velocity; DEPTH outputs on the depth axis with no velocity conversion applied; FREQUENCY outputs on the frequency axis. This parameter is set automatically and is not directly editable from the user interface; it is controlled by the upstream gather domain configuration.
Selects whether the module runs on CPU or GPU. Kriging-based slope interpolation is a CPU-bound operation; selecting GPU has no effect for this module.
Configuration for distributing processing across a compute cluster.
Minimum number of gathers sent per work chunk during distributed execution.
When enabled, restricts CPU thread count per cluster node to the value in Number of threads.
Optional text appended to the distributed job name for identification in the cluster queue.
When enabled, applies the CPU affinity mask specified in Affinity to restrict execution to specific processor cores.
CPU affinity mask applied when Set custom affinity is enabled.
Maximum number of CPU threads used during execution. The Kriging interpolation is parallelised across bins so increasing thread count reduces runtime proportionally on multi-core systems.
When enabled, this module is bypassed and data passes through unchanged.
Gather of traces where amplitude represents the interpolated inline dip-angle slope at each bin and time/depth sample. Connect to downstream tomography or velocity updating modules that accept slope-gather input.
Gather of traces where amplitude represents the interpolated crossline dip-angle slope at each bin and time/depth sample. Used together with the inline slopes gather for 3D tomographic inversion.