Headers

Every seismic trace carries a block of metadata values — called trace headers — that describe its acquisition geometry and identity: the shot-point number, receiver position, CDP (Common Depth Point) bin assignment, offset, line ID, and many other attributes. These header values control how g-Platform sorts, selects, bins, and displays data throughout the processing workflow. Accurate, consistent headers are a prerequisite for correct velocity analysis, stacking, and migration.

The Headers group contains modules for inspecting, editing, correcting, and reorganising trace headers. The tools in this group are typically applied after geometry loading — to repair numbering errors, populate missing fields, reorder traces for downstream processing, or compute derived header values from existing geometry information. Use these modules whenever headers in the raw or partially processed dataset do not match the expected values for your processing flow.

Modules in this group

Bad values fixing — Scans every sample of every trace and replaces numerically invalid values (infinite values and NaN) with a user-defined constant. Apply this early in any workflow to prevent corrupted samples from propagating into amplitude analysis, deconvolution, or migration.

Copy header — Copies the value from one trace header field into another. Use this to duplicate geometry attributes (for example, copying the CDP X coordinate into a spare field for later use) or to remap non-standard header field assignments into the positions expected by downstream tools.

Correct SP numbers (2D) — Repairs or renumbers shot-point (SP) header values for 2D seismic lines. Correcting SP numbers is necessary when field records contain duplicate, missing, or out-of-order SP values that would otherwise cause errors in geometry assignment and processing QC along the line.

Correct SP numbers (3D) — Repairs or renumbers shot-point header values for 3D surveys, where SP numbering must be consistent across multiple source lines. Use this when 3D field data contains SP numbering inconsistencies that prevent correct geometry loading or bin assignment.

Correct Source Receiver Line ID (2D-3D) — Corrects the line identifier values stored in the source-line and receiver-line header fields. Accurate line IDs are essential for 3D geometry validation and for any processing step that groups or selects traces by line, such as cross-line stacking or receiver-line noise attenuation.

Headers manipulation — Provides a general-purpose header editor that lets you modify any trace header field using mathematical expressions and conditional logic. Use this module for custom header calculations that are not covered by the specialised correction modules — for example, computing a derived offset class, scaling coordinate values, or combining two header fields into a new attribute.

Load trace headers from ASCII — Reads header field values from an external ASCII file and writes them into the corresponding trace headers. Use this to populate header fields from observer logs, navigation files, or any tabular source that is not in a standard SPS or SEG-Y geometry format.

Offset bin generator — Assigns traces to offset classes (offset bins) and writes the bin index into a trace header field. Offset binning is used to create super-gathers, pre-stack partial stacks, or offset-limited stacks for AVO analysis and inversion workflows.

Rebuild sequence numbers — Resets and recomputes the trace sequence number header fields so that they are sequential and contiguous. Run this after trace editing, killing, or merging operations that may have left gaps or duplicates in the sequence numbering.

Select traces — Filters the input gather to retain only those traces that satisfy user-defined header criteria (for example, traces within a specific offset range, shot range, or CDP range). This is a general-purpose trace selection tool used to extract subsets of data for targeted QC, testing, or partial processing.

Sort gather — Reorders the traces within a single gather according to a chosen header field, such as offset or receiver number. Many processing steps (velocity analysis, Radon demultiple, AVO) require traces to be in offset order within each gather; use this module to enforce that order before applying such algorithms.

Sort traces — Re-sorts the entire trace dataset into a new gather order defined by one or more header keys. For example, re-sorting from shot order into CDP order, receiver order, or offset order to prepare data for a specific processing stage or output format.

CDP-Offset To Source-Receiver — Computes and writes source and receiver coordinate header fields from the CDP midpoint and offset information already present in the trace headers. Use this when source and receiver coordinates are missing or incorrect but CDP and offset values are reliable, which is common with certain vintage datasets or after re-binning operations.

Recreate CDP numbers — Recomputes the CDP bin number header field from the source and receiver geometry. Use this after geometry editing, line straightening, or re-binning to ensure that CDP header values reflect the actual midpoint positions rather than the original field values, which may be inaccurate or inconsistent with the current bin grid.