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<< Click to Display Table of Contents >> Navigation: Tomography > MF Params to Tomo Params (Common Offset) |
MF Params to Tomo Params (Common Offset) converts MultiFocusing parameter datasets into tomography parameter files suitable for stereo tomography velocity model building. The module scans the MultiFocusing parameter storage for locally coherent events at each common-offset class, extracts their travel times, source and receiver slopes, and other attributes, then exports them in the format required by the Stereo tomography solver. The user can interactively pick additional events on the displayed stack or semblance panels, apply horizon constraints, and control quality thresholds before creating the final tomo output files.
The MultiFocusing parameter database file (.kdb) containing the pre-computed MF parameters for all common-offset classes. This file is produced by a preceding MultiFocusing parameter extraction step.
The 3D picking item that stores manual and automatic horizon picks used to guide the tomo parameter extraction. Connect from the corresponding MF parameter or horizon picking module.
Common component that controls how the inline stack and semblance images are constructed for display and interactive picking. These settings are shared with the MF image creation workflow.
The current common-offset class (m) being displayed and edited in the pick panel. Default: 1000 m. Change this value to navigate between offset classes and verify or correct the event picks for each offset band.
Index of the horizon layer currently selected for interactive editing. The list is populated from the horizons imported or picked in this module.
Reference datum elevation (m) used when converting horizon times to depths during tomo file creation. Default: 0 m.
Start time (s) of the data window displayed and processed. Default: -1 s (use full record length). Set to restrict extraction to a specific time interval.
End time (s) of the data window. Default: -1 s (use full record length).
First CMP bin index of the data range to process. Default: -1 (process all bins). Set to restrict extraction to a portion of the line.
Last CMP bin index of the data range to process. Default: -1 (process all bins).
Controls the computation speed versus accuracy trade-off during tomo parameter extraction. Default: Fast. Fast uses an optimised pipeline for quick results suitable for initial tests; Long applies more rigorous slope estimation for higher-quality tomo points.
Half-aperture in number of traces used for local slope estimation around each event. Default: 10 traces. Minimum: 1. A larger aperture provides a more stable slope estimate but can smooth out lateral variations in dip.
Half-aperture in number of time samples used in the local coherence estimation. Default: 10 samples. Minimum: 1.
Maximum dip angle (degrees) of the zero-offset ray allowed when extracting coherent events. Default: 15 degrees. Range: 1–90 degrees. Events with steeper zero-offset slopes are rejected as noise.
Minimum semblance value an event must achieve to be accepted as a valid tomo data point. Default: 0.05. Minimum: 0. Increase this threshold to accept only high-coherence events and reduce noise in the tomo dataset, at the cost of fewer data points. Decrease if the survey has low fold and few events pass the threshold.
Minimum normalised amplitude an event must have to be accepted as a tomo data point. Default: 0.005. Events with amplitude below this threshold (relative to the local trace maximum) are discarded as noise.
Minimum CRE (Common Reflection Element) coherence estimate required to retain an event. Default: 10000. This internal quality metric from the MultiFocusing analysis filters out events with poor CRE coherence.
Scaling factor applied to the CRE coherence estimate before comparing with MIN_CEE. Default: 0.1. Adjust to calibrate the relative sensitivity of the CRE quality filter.
Path and file name for the output tomo correlation file (.corr). This file stores the extracted tomo data points and is used as input to the Stereo tomography solver.
Type of offset data used for tomo extraction. Default: CO. Options: CO — common-offset events only; ZO — zero-offset events only; ZO_CO — both zero-offset and common-offset events combined.
Container grouping offset range settings used to define the common-offset classes for extraction.
When enabled, the offset classes are computed automatically from OffsetFrom, Offset To, and Offset increment. When disabled, offset classes are read directly from the storage file.
Minimum source-receiver offset (m) of the first class to extract.
Maximum source-receiver offset (m) of the last class. Default: 2000 m.
Offset step (m) between successive common-offset classes. Default: 1000 m.
Container grouping settings for importing horizon constraints from ASCII files via the Import horizon from ASCII custom action.
Specifies whether the horizon times in the ASCII file are referenced to the processing Datum or to Topography. Default: Datum.
Reference datum elevation (m) used when Location is Datum. Default: 0 m.
Time unit in the ASCII horizon file. Default: Milliseconds. Select Seconds when appropriate.
Container grouping parameters that govern the manual horizon picking tool in the interactive stack display.
Time radius (s) around the cursor position searched for the pick magnet snap. Default: 0.020 s. Minimum: 0.004 s. The magnet snaps the pick to the closest amplitude extremum within this window.
Polarity of the amplitude extremum sought by the pick magnet. Default: Positive phase. Select Negative phase when picking on troughs.
Minimum amplitude of the event for the magnet to snap to it. Default: 2.5. Increase to snap only to strong events; decrease on low-amplitude data.
Strategy for selecting the snap target. Default: Nearest — snaps to the nearest amplitude peak within the window; Max energy — snaps to the highest-amplitude peak within the window.