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Refill TT recalculates and updates the travel-time (TT) table file used in Kirchhoff pre-stack depth migration (PSDM). When the depth velocity model is updated — for example after a tomographic inversion — the existing travel-time tables become inconsistent with the new model and must be recalculated. Instead of running a full travel-time computation from scratch, this module recomputes only the travel-time values for bins that exist in the input TT file, using the updated velocity model, and writes the corrected tables to a new output TT file.
The module supports VTI anisotropic travel-time calculation when the Make anizo flag is enabled and the corresponding Thomsen parameter models (Delta and Epsilon) are provided. Use this module as part of an iterative velocity update workflow: after each tomographic update, run Refill TT before re-running the depth migration.
Path to the existing travel-time table file (TTFILE format) that defines the geometry — the set of output image bins and their associated source point positions. The geometry (bin grid, datum level, sampling) from this file is preserved; only the travel-time values are updated.
Path and filename for the output travel-time table file containing the recalculated travel times. The output file will have the same geometry as the input file but with travel times derived from the updated velocity model.
Updated depth-domain P-wave interval velocity model. This is the primary input used to recompute travel times. The model must be on a constant datum and its geometry (number of traces, spatial coverage) must match the bin grid of the input TT file.
Thomsen delta (δ) anisotropy parameter model in depth. Required when Make anizo is enabled. Delta controls the NMO velocity correction for VTI media. Must have the same geometry as the Depth velocity model.
Thomsen epsilon (ε) anisotropy parameter model in depth. Required when Make anizo is enabled. Epsilon controls the horizontal velocity in VTI media. Must have the same geometry as the Depth velocity model.
When enabled, the travel-time calculation uses VTI anisotropy with the Delta and Epsilon parameter models. When disabled (default), isotropic travel times are computed. Enable this only when a credible anisotropy model is available from well data or anisotropy estimation workflows.
Grid spacing in the X (crossline) direction in metres. This field is read-only and is automatically set from the input depth velocity model geometry when the model is loaded. It must match the crossline sampling of the velocity grid used during the original TT calculation.
Grid spacing in the Y (inline) direction in metres. Automatically populated from the velocity model geometry. Must match the inline sampling of the velocity grid.
Maximum lateral search radius in metres (default: 500 m) used when interpolating travel times from the grid to off-grid source positions. Increase this value if source points fall outside the standard grid coverage, or reduce it to speed up computation on very dense grids.
Reference datum elevation in metres. This value is automatically set from the input velocity model and is read-only. The datum must be at or above the highest topographic point in the survey area.
Replacement velocity in m/s (default: 0 m/s) used to fill the layer between the topographic surface and the datum in the velocity model. This should match the replacement velocity used when the original TT tables were computed, ensuring consistency between the static corrections and the travel-time tables.
Inline decimation factor for the output travel-time grid (default: 1, full resolution). Setting this to 2 writes every second inline, halving the output TT file size. Use larger values only when storage space is critical and the migration can tolerate coarser TT sampling.
Crossline decimation factor for the output travel-time grid (default: 1, full resolution). Apply the same considerations as for the inline step.
Inline number of a specific bin to process individually for QC purposes. When set to a valid inline (and a matching crossline is provided), only the TT for that single bin is recalculated, allowing rapid visual inspection of the result. Set to -1 to reset the selection and process all bins.
Crossline number of the specific bin to process individually (companion to Selected bin inline). Set to -1 to reset the selection.
Selects whether the travel-time computation runs on CPU or GPU. GPU execution significantly accelerates the finite-difference eikonal solver for large velocity models.
Configuration for cluster/distributed execution, enabling the TT recalculation to be split across multiple compute nodes for large surveys.
Minimum number of bins processed per distributed job chunk. Larger values reduce scheduling overhead.
Maximum threads per compute node for distributed processing. Set this to leave system resources available for other jobs on shared cluster nodes.
Optional text suffix appended to the distributed job name for identification on a shared cluster.
Enables manual CPU core affinity assignment. Leave disabled unless performance tuning on NUMA architectures is required.
CPU core affinity mask. Used only when Set custom affinity is enabled.
Number of CPU threads to use. Set to match the number of available physical cores for maximum throughput.
When enabled, this module is bypassed without executing, allowing it to be temporarily disabled in a processing flow without deleting it.