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The Raytracing modeling module traces seismic rays through a depth interval velocity model and computes theoretical first-break travel times for all source-receiver pairs. The results are exported as a tomographic item (tomo item) that can be connected to tomographic inversion or statics correction modules for model updating.
Use this module to generate synthetic travel-time tables from an existing depth velocity model as a starting point for first-break tomography, or to quality-check the consistency of a near-surface velocity model against observed first-break picks.
Link to the depth-domain interval velocity model through which rays will be traced. This model defines the spatial velocity distribution used to compute travel times. Ensure the model covers the full offset range and depth range of the survey.
Maximum ray take-off angle (degrees) from vertical used to seed the raytracing fan. Default: 15°. Valid range: 1–45°. Rays are traced within this angular aperture from the source. Increase this value when the near-surface has strong lateral velocity gradients that may bend rays to large angles; decrease it to reduce computation time when steep rays are not of interest.
Lateral search step along the X (inline) direction (m) used when scanning for ray arrival positions on the receiver grid. Default: 50 m. Smaller values improve the accuracy of ray-to-receiver matching but increase computation time.
Lateral search step along the Y (crossline) direction (m) used when scanning for ray arrival positions on the receiver grid. Default: 50 m. For 2D surveys set this to a large value so that searching is effectively one-dimensional along the line direction.
Minimum near-surface velocity (m/s) used as the initial reference velocity for raytracing in the weathering layer. Default: 2000 m/s. Set this to the expected velocity at the top of the near-surface model. If the velocity model already contains an accurate near-surface column, this value acts as a lower bound guard against unrealistically slow rays.
Integration time step (s) used to advance rays along their paths. Default: 0.01 s. Valid range: 0.001–1 s. Smaller time steps improve ray path accuracy at the cost of more computation. Use a finer step (e.g., 0.001 s) when the velocity model has thin high-contrast layers where rays bend sharply.
Selects whether the module executes on the CPU or an available GPU.
Enables distributed processing across multiple compute nodes in a cluster.
Minimum number of traces dispatched to each compute node per batch during distributed execution.
When enabled, limits the number of threads used on each cluster node to the value set in Number of threads.
Optional text appended to the distributed job name to distinguish this run in the cluster queue.
When enabled, allows manual assignment of CPU core affinity for processing threads via the Affinity parameter.
CPU core affinity mask applied when Set custom affinity is enabled.
Number of CPU threads used for parallel execution. Set to the number of available physical cores for best performance.
When enabled, the module passes data through unchanged without performing raytracing. Use this to temporarily disable the module in a workflow without disconnecting it.
Tomographic data item containing the computed ray paths and theoretical first-break travel times for all modelled source-receiver pairs. Connect this output to a refraction tomography inversion module to compare modelled travel times against observed first-break picks and update the near-surface velocity model.