Arbitrary lines
Arbitrary lines - contains all seismic arbitrary lines created in g-Space
Right mouse button on the icon allows to:
- Add arbitrary line
- Clear arbitrary lines
- Add folder
An arbitrary line is a user-drawn path through a 3D seismic cube that extracts seismic traces along any geometry — not only the native in-line / cross-line grid. Use it to follow a geological feature, connect key wells on a single panel, or build a custom cross-section through a field. The path is defined interactively in a 3D or map view and the resulting gathers appear in a dedicated 2D view.
Creating an arbitrary line
- Open a 3D view or Location map showing the target cube.
- Enable arbitrary-line creation from the view toolbar and click the cube to place successive anchor points (corners).
- Double-click the line to build it, or use Update current arbitrary line from the right-click menu to rebuild it at any time. g-Space builds the bin sequence along the polyline and extracts traces for every domain available on the cube (time, depth, offset …).
- Manage existing lines (rename / delete / activate) from the Data manager under the Arbitrary lines node.
While you are picking a line through a 3D cube or a free-hand 3D line, you can also reshape it. Press the left mouse button on or very close to an existing point to drag that point to a new position, or on the line between two points to drag the whole path; the line and the section extracted along it follow the points while the button is held, and the new geometry is kept when you release the button. Click clear of the line when you want to add another point instead. A line that follows 2D seismic lines cannot be reshaped this way.
When you add an arbitrary line, g-Space suggests a name in the Set name of the arbitrary line dialog: New arbitrary line, or New arbitrary line 2, New arbitrary line 3 and so on when a line with the previous name already exists. Accept the suggestion or type your own name in Arbitrary line name; names must be unique, so g-Space asks again if the name you enter is already taken.
When you place the first point of a new line, g-Space appends a type suffix to its default name (New arbitrary line) so the different arbitrary-line types are easy to tell apart in the Data manager:
- _2D — a line that follows existing 2D seismic lines
- _3D — a line extracted through a 3D cube
- _Free — a free-hand 3D line
Only lines that still carry a suggested default name — with or without its counter — are renamed automatically, a line you have already renamed yourself keeps its name.
Parameters
These settings are grouped under Arbitrary line params:
- Create arbitrary line — builds the line from the points you picked. When it is cleared, the picked points are discarded instead of producing a line. Enabled by default.
- Arbitrary line step — distance between consecutive bins along the line. Default 25 m.
- Arbitrary line max search distance — maximum lateral distance from the polyline beyond which 3D traces are ignored when interpolating. Default 200 m.
- Arbitrary line moving step — distance the whole line is shifted sideways each time you press Page Up or Page Down in the view. The line moves perpendicular to the straight line joining its first and last points, and the two keys move it in opposite directions. This works for a line through a 3D cube and for a free-hand 3D line that has at least two points, but not for a line that follows 2D seismic lines. Default 200 m.
- Straighten on 3D view — when enabled, the line is rendered as a straight plane inside the 3D view for easier inspection.
What you can do with an arbitrary line
- Display extracted gathers in the dedicated 2D view and pick horizons / faults on them as on any seismic section.
- Display several arbitrary lines at the same time in a 3D view — a time or depth 3D view can draw all the arbitrary lines of the project, not only the current one. Select or clear the check box of a line under Arbitrary lines in the Data manager to show or hide it in the view.
- Inspect the nearest wells and nearest 2D lines to each corner — g-Space keeps per-corner associations for quick context switching.
- See which 2D seismic lines the path crosses — the view prints their names in the annotation area above the section. Clear Show line names in the View section of the Visual Settings panel to hide these labels; the option is selected by default.
- Convert the extracted path into a standalone 2D line or export it to SEG-Y for sharing.
See Also