Creating internal velocity picks from an external velocity model.
Create Vrms Pickings from Vrms Model module converts a continuous Vrms velocity model into discrete Vrms picking functions that can be directly used for NMO correction and velocity analysis workflows.
This module samples the Vrms model spatially and vertically within a user-defined time range and geometry step, and outputs the velocities in a g-Platform internal format (NMO picking) compatible with subsequent processing modules. Controlled sampling, gating, and interpolation ensure that the generated picks are stable, smooth, and geologically consistent.
Gating options (constant or time-variant) are applied to limit short-wavelength velocity fluctuations, while optional extremum-based point selection helps capture significant velocity changes without introducing noise. Angle-related gates may also be used to manage angle-dependent effects in advanced moveout workflows.
Overall, this step bridges the gap between a smoothed Vrms velocity model and practical, usable velocity picks, ensuring reliable NMO correction, improved stacking, and stable migration results.
Vrms model - this is the input RMS velocity model that is used to generate internal velocity format file. Connect/reference to Output Velocity model.
Geometry for new model - specify the geometry for the new velocity model.
Geometry step - Defines the spatial sampling interval used when converting velocities. Controls how often velocity values are extracted from the velocity model.
For example, if the user wants to give a geometry step of 200 points, it generates the velocities at every 200th point.
Out picking file - specify the destination output file name and it's path. This file is an internal format RMS velocity file.
Make points by extremums - Generates Vrms picking points at velocity extrema. Useful for automatic picking of significant velocity changes.
Make points by extremums - false -
Time step - Vrms points are created using uniform sampling instead. Time interval between successive Vrms samples. Controls vertical resolution of the output velocity picks.
Output format { NMO picking, MF picking } - select output file format from that drop down menu. By default, NMO picking.
Time start - Start time for Vrms conversion. Velocities above this time are ignored.
Time stop - End time for Vrms conversion. Limits the maximum time range of the output velocities.
Gate interpolation type vrms { Constant, Time variant } - Specifies how Vrms values are interpolated within time gates. Constant applies fixed gating; Time Variant allows gate size to vary with time. By default, Constant.
Gate percent vrms - Defines the percentage of Vrms variation allowed within each gate. Used to control smoothing strength during conversion.
Time-gate vrms factors - Scaling factors applied to Vrms values within defined time gates. Used to stabilize or adjust Vrms behavior in specific intervals.
Time-gate vrms - Time–Gate Vrms entries allow multiple gates at different times.
Time - Central time of the Vrms gate.
Gate - Defines where the gate is applied.
Angle - Defines the reference angle used for velocity or moveout control. Primarily used in angle-dependent velocity workflows.
Gate interpolation type angle { Constant, Time variant } - Specifies interpolation behavior of angle gates. Time Variant allows angle gates to change with time.
Gate angle - Defines the angular aperture used for angle gating. Controls sensitivity to angle-dependent velocity effects.
Time-gate angle - Time–Gate Angle entries allow angle control at different time intervals.
Time-gate angle -
Time - Central time at which the angle gate is applied.
Gate - Used to control angle behavior at specific depths.
Number of threads - One less than total no of nodes/threads to execute a job in multi-thread mode. Limit number of threads on main machine.
Skip - By default, FALSE(Unchecked). This option helps to bypass the module from the workflow.
There are no output vista items from this module. There will be an output file which needs to be mentioned in the Parameters.
There is no information available for this module.
In this example workflow, we are reading an external velocity model which is in SEGY format. We are reading this velocity file by using Read SEG-Y traces module. Make the changes to Load data to RAM as YES from NO. The Output gather from this module will be referenced/connected to Velocity model of Create Vrms picking from Vrms model module.
Make the necessary references/connections as required by Crate Vrms picking from Vrms model module.
After setting up the necessary references/connections and parameters, execute the module and check the output file. It will be an ASCII file with an extension of .corr (which is a g-Platform internal file format for velocities and mutes).
There are no action items available for this module so the user can ignore it.
YouTube video lesson, click here to open [VIDEO IN PROCESS...]
Yilmaz. O., 1987, Seismic data processing: Society of Exploration Geophysicist
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