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Geometry QC azimuthal is an interactive quality-control module for verifying the accuracy of land or transition-zone acquisition geometry. It examines how well the recorded seismic data align with the assigned source and receiver positions by stacking traces azimuthally and checking whether the resulting image is coherent and flat after a linear moveout (LMO) correction. Geometry errors — such as swapped source/receiver coordinates, mis-assigned shot numbers, or incorrect station coordinates — produce incoherent or misaligned stacks in one or more azimuth sectors, making them easy to identify visually.
For each source or receiver point, the module groups all contributing traces into user-defined azimuth sectors. Within each sector the LMO-corrected (and optionally first-break-shifted) traces are stacked together and displayed as a separate time window in a QC gather. The full-survey QC gather thus shows one stacked azimuthal panel per acquisition point, ordered by point sequence number. This multi-panel display lets the interpreter rapidly scan the entire dataset for points with anomalous moveout, low fold, or systematic timing errors that indicate a geometry problem.
The module also provides an interactive location map showing all sources and receivers. Clicking on any point in the map or in the QC gather loads the corresponding individual source or receiver gather for detailed inspection, with the LMO curve and any imported first-break picks overlaid. First-break picks can be imported via the Import FB-picking custom action, enabling comparison of picked traveltimes against the LMO trend as an additional geometry check. Use this module after loading geometry and before running any surface-consistent corrections or statics.
The trace header table containing the geometry information for all traces in the survey: source and receiver coordinates (X, Y), offsets, and station sequence numbers. This is the primary geometry dataset that the module validates. All source and receiver points are extracted from this header table and displayed on the location map. The offset range filtering parameters (Min offset / Max offset) are applied against the offsets stored here.
A handle to the raw seismic amplitude data in SEG-Y format. The module reads trace amplitudes from this source in order to perform the azimuthal stack and produce the QC gathers. The data is read in large batches and is not modified — this input is read-only. Ensure that the SEG-Y file is consistent with the trace headers connected to the Input trace headers item.
The minimum source-receiver offset (in meters) to include when building the azimuthal stacks and calculating the average misfit between the data and the LMO trend. Traces with offsets shorter than this value are excluded from both the QC gathers and the goodness-of-fit statistics. The default value is 0 m, meaning all near-offset traces are included. Increase this value to suppress near-offset noise or guided waves that do not follow a linear moveout trend and would otherwise degrade the QC stack quality.
The maximum source-receiver offset (in meters) to include when building the azimuthal stacks. Traces with offsets beyond this value are excluded. The default value is 15000 m. Set this to the maximum usable offset for your survey to avoid contaminating the stacks with far-offset traces that are poorly illuminated or strongly affected by multiple reflections. In typical land surveys, setting this to the expected maximum offset distance ensures only valid traces contribute to the geometry QC.
Controls which QC gathers are computed when the module is executed. The available options are:
SRC — builds the azimuthal QC gather for sources only. Each trace in the output represents one source point, with azimuth sectors stacked side by side. This is the default and is the most common choice for verifying source-point geometry.
RCV — builds the azimuthal QC gather for receivers only. Use this to verify receiver-point geometry independently of the source geometry.
SRC and RCV — computes both source and receiver QC gathers simultaneously. This is the most thorough option but requires more processing time and memory for large surveys.
The half-length of the time window (in seconds) used when extracting a trace segment for each azimuth sector stack. The full window displayed for each azimuth sector is twice this value, centered on the LMO-corrected event time. The default is 0.050 s (50 ms). Increase this value to capture a wider portion of the wavelet when the dominant frequency is low or when the LMO correction leaves some residual moveout. Reduce it to tighten the display and improve visual separation between azimuth sectors. This value must not exceed the Half quadrant time window.
The half-length of the time slot (in seconds) allocated in the QC gather output for each azimuth sector. This determines the spacing between adjacent azimuth panels in the output gather. The default is 0.200 s (200 ms). This value is automatically enforced to be at least as large as the Half time window. Increase it to provide more separation between azimuth panels (useful when the LMO velocity is low and residual moveout is large). The total time axis length of the QC gather equals twice this value multiplied by the number of azimuth sectors defined in the Azimuth params collection.
The apparent velocity (in m/s) used to compute and apply a linear moveout correction to the traces before azimuthal stacking. Linear moveout shifts each trace by an amount proportional to its offset divided by this velocity, flattening direct arrivals or refracted waves so that traces from different offsets align in time for stacking. The default is 0 m/s (no LMO correction applied). Set this to the near-surface refraction velocity or the velocity of the wave event being used for QC — typically the first-break velocity (e.g., 1500–3000 m/s for typical land datasets). A correct LMO velocity will cause valid geometry points to show a flat, coherent stack across all offsets, while geometry errors will appear as misaligned or incoherent panels. This parameter is also used to overlay the LMO moveout curve on the individual gather views.
The orientation angle (in degrees from North, measured clockwise) of the source line direction. This value is used to draw the source line direction cross-hair overlay on the selected-source location map panel, helping the interpreter visually confirm which azimuth sector corresponds to inline versus crossline directions relative to the acquisition grid. The default is 0 degrees. Set this to the actual source-line bearing of your survey geometry.
The orientation angle (in degrees from North, measured clockwise) of the receiver line direction. This value is used to draw the receiver line direction cross-hair overlay on the selected-receiver location map panel. The default is 90 degrees, which is appropriate for an orthogonal geometry where receiver lines run perpendicular to source lines. Adjust this value to match the actual receiver-line bearing of your acquisition layout.
A collection of azimuth sector definitions. Each entry in the collection defines one azimuth sector by specifying two sub-parameters:
Azimuth from — the starting angle (in degrees, 0–360) of this azimuth sector.
Azimuth to — the ending angle (in degrees, 0–360) of this azimuth sector.
By default four sectors are pre-configured, dividing the full 360-degree range into four equal quadrants: 0–90, 90–180, 180–270, and 270–360 degrees. Each sector produces one time panel in the QC gather output. You can add, remove, or resize sectors to match your acquisition geometry — for example, using just two sectors (inline vs. crossline) or eight sectors for finer azimuthal discrimination. At least one sector must be defined for the module to execute. The azimuth of each trace is computed as the bearing from the source to the receiver (for receiver-side QC) or from the receiver to the source (for source-side QC).