Seismic Volumes Properties
This page documents the properties available for SEG-Y-backed seismic volume objects in VRGS. These properties appear in the Properties panel when a Seismic Volume is selected in the Data Tree or 3D view.
For a workflow-oriented overview see the Seismic Volumes guide.
CSeismicVolume
File: SeismicVolume.cpp
Properties available for CSeismicVolume objects. Properties are grouped
in the panel under: Volume identity, Status, Geometry, Trace
header bytes, Sections, Blend channels (blend volumes only),
Display, Memory, Diagnostics, Last pick.
CSeismicVolume - Name
Property name: Name
Description (in app): Volume name
What it does
The display name shown in the Data Tree and on info billboards.
Defaults to the SEG-Y file's stem on import.
When to use it
Rename when you have multiple cubes with similar filenames (e.g. raw
vs filtered, near vs far stack) so the tree stays readable.
CSeismicVolume - SEG-Y file
Property name: SEG-Y file
Description (in app): Path to the bound SEG-Y file
What it does
Read-only display of the absolute filesystem path the volume was
imported from. The file is not copied into the project; this is the
live reference.
Notes
If the file moves, the volume becomes a "broken link" on next reload
and won't render. There is no in-app re-link UI yet; edit the project
database directly or re-import.
CSeismicVolume - Sidecar
Property name: Sidecar
Description (in app): Cached scan index location
What it does
Read-only display of the on-disk sidecar index file location. Lives
under <project folder>/SEISMIC_INDEXES/<basename>.segyidx.
When to use it
Inspect when you need to confirm the cache exists, or to delete it
manually to force a re-scan.
CSeismicVolume - Status
Property name: Status
Description (in app): Async scan progress / volume binding state
What it does
Read-only progress indicator. Shows Scanning N% while the background
scan runs, otherwise either nothing (when bound and ready) or the last
scan error message.
Notes
The value is sampled when the property panel is opened or refreshed —
it does not auto-update during a scan. Click the volume in the tree
again to refresh.
CSeismicVolume - Inlines / Crosslines / Trace
Property name: Inlines, Crosslines, Trace
Description (in app): Read-only geometry summary from the index
What it does
Display the inline range, crossline range, and (samples × interval)
from the scan. Useful sanity check after a fresh import.
Notes
Absurd ranges (e.g. 536870912 — 536936448) typically indicate the
trace-header byte locations are wrong; pick a different preset or hand-
edit them.
CSeismicVolume - Z axis
Property name: Z axis
Description (in app): Vertical axis kind
What it does
Dropdown choosing how the sample axis is interpreted: Time (ms TWT),
Depth (m), or Depth (ft). Inferred from the binary header
measurement_system field on first scan; user-overridable thereafter.
When to use it
Override when the binary header is wrong or absent and the data is
clearly the other kind.
CSeismicVolume - Trace header byte fields
Property names: Inline byte, Inline size, Crossline byte,
Crossline size, CDP X byte, CDP Y byte, Scalar byte
Description (in app): 1-based byte offsets and sizes for trace
header geometry fields
What it does
Tell the scanner where to read the geometry integers from each 240-byte
trace header. Sizes are 2 (i16) or 4 (i32). Defaults match SEG-Y
rev 2.1.
When to use it
Real-world legacy files routinely place inline at byte 5, 9, or 21
instead of the standard 189. Edit these to match your file's
convention.
Notes
Editing alone has no effect — you must trigger a re-scan via the
Apply field map checkbox below. Most files match one of the
Preset options; use that dropdown rather than editing by hand.
CSeismicVolume - Preset
Property name: Preset
Description (in app): Common byte-location conventions
What it does
Dropdown that fills the seven byte fields from a named convention:
Custom (no-op), Auto-detect (from file), Rev 2.1 standard,
Legacy (5/9 inline-shotpoint), OpendTect (9/13). Selecting one
writes the values, then auto-resets the dropdown back to Custom so
re-picking the same preset fires it again.
Auto-detect (from file) re-runs the import-time detector against the bound file: it parses documented byte positions out of the textual header's C-cards and scores candidate byte pairs empirically over sampled trace headers, then fills the fields with its best guess.
When to use it
First thing to try when geometry parses incorrectly — start with
Auto-detect (from file), then the named conventions.
CSeismicVolume - Apply field map
Property name: Apply field map
Description (in app): Re-scan the file with the current byte
locations
What it does
One-shot trigger checkbox. When toggled, deletes the sidecar and
launches a fresh asynchronous scan with the current byte locations.
When to use it
Whenever you've changed any of the byte fields above.
Notes
The scan runs on a worker thread; the volume becomes unbound until it
finishes. Watch Status for progress.
CSeismicVolume - Show inline / Show crossline / Show time slice
Property names: Show inline, Show crossline, Show time slice
Description (in app): Draw the inline / crossline / time-depth slice
What it does
Three checkboxes in the Sections group that toggle each orthogonal
section on or off independently, so you can display any subset of the
three planes.
When to use it
Show a single inline while interpreting, add the crossline for 3-D
context, drop the time-slice when it clutters the view. Hiding a section
leaves its active line / crossline / sample index untouched, so
re-showing it returns to exactly where you were.
Notes
Each checkbox appears only once its section has a valid position (the
survey centre is defaulted on first bind). On a 2D line only the
line's own section is defaulted on.
CSeismicVolume - Inline / Crossline / Time slice
Property names: Inline, Crossline, Time slice
Description (in app): Active section indices
What it does
The inline number, crossline number, and sample index of the currently
visible orthogonal sections. Set to a section's index to enable that
plane; the section is rendered as a textured quad coloured by the
active colormap.
When to use it
Edit to navigate through the cube. Each field has a spin control
that steps through the survey, and typed values snap to the grid
(the nearest real inline/crossline). Defaults to the centre on first
bind. Slice changes bake on a background worker — the previous slice
keeps showing until the new one is ready, so scrubbing never stalls
the view.
Notes
On a 2D line only the line's own section is active; the orthogonal
slice (a one-trace sliver) and the time-slice (a 1-sample row) are not
defaulted on.
CSeismicVolume - Gather trace
Property name: Gather trace (shown only when the file is pre-stack)
Description (in app): Pre-stack ensembles: 0 = brute stack of every
trace in the cell; N = show only the Nth trace
What it does
Chooses what a pre-stack ensemble (several traces per inline/crossline
cell) reads as. 0 (default) averages the whole ensemble — a brute
stack. N shows only the Nth trace of each ensemble (1-based,
clamped to the fold). The selection applies to every read:
sections, the wiggle overlay, and the 3D volume render, whose brick
atlas re-streams with the new selection.
When to use it
Quick offset QC — flip between near (1) and far (highest N) offsets
to see moveout or offset-dependent amplitude without leaving the
viewer.
Notes
No NMO correction is applied — this is inspection, not processing.
Changing the value clears the trace cache and re-bakes the visible
sections. Only appears when Pre-stack fold (Diagnostics) is above 1.
CSeismicVolume - Wiggle overlay
Property name: Wiggle overlay
Description (in app): Draw wiggle traces over sections
What it does
Toggles the wiggle-trace overlay on inline and crossline sections. Each
trace is drawn as a line strip whose vertices are offset along the
across-trace axis by the (gain × polarity × amplitude) at each sample.
When to use it
Enable for QC and detailed inspection; disable for fast pan/zoom or
when the wiggle clutter obscures the underlying section colour.
Notes
Time-slices have no time axis and are not overlaid. 2D lines drawn as
curtains (crooked acquisition paths) also skip the wiggle — it
would hang off the straight chord rather than follow the curtain.
CSeismicVolume - Wiggle scale
Property name: Wiggle scale
Description (in app): Wiggle amplitude as fraction of trace spacing
What it does
Scales the wiggle excursion. 1.0 = a unit-amplitude trace swings by one
trace-spacing; 0.5 (default) = half a trace-spacing.
When to use it
Increase for sparse cubes where wiggles are barely visible; decrease
in dense surveys to avoid neighbouring wiggles overlapping.
CSeismicVolume - Wiggle color
Property name: Wiggle color
Description (in app): Line colour for wiggle traces
What it does
Pick the colour used to draw wiggle line strips.
When to use it
Black on light colormaps, white on dark colormaps. Bright colours work
well as overlays on grayscale.
CSeismicVolume - 3D volume render
Property name: 3D volume render
Description (in app): Composite the full cube with ray-marching
What it does
Toggles brick-paged, level-of-detail 3D ray-marching of the entire
cube. A pyramid of coarser levels sits above the full-resolution
bricks; the coarsest level (the whole survey in at most 64 bricks) is
always kept resident, so the full cube appears within seconds of
enabling the toggle at overview resolution, regardless of file size.
Finer bricks then stream in near the camera, front-to-back; while they
stream, the ray-marcher falls back to the coarser data underneath, so
refinement is progressive and there are never holes.
When to use it
Use to see large-scale 3D continuity, or for overview screenshots.
Toggle off when interpreting a single section to keep the frame rate
responsive.
Notes
Moving the camera to a new region degrades resolution, not coverage —
coarse data shows immediately and sharpens as fine bricks page in.
Disabling the toggle frees the GPU atlas memory. Hidden on 2D lines
(a single line has nothing to ray-march).
CSeismicVolume - Show bounding box
Property name: Show bounding box
Description (in app): Wireframe outline of the volume extent
What it does
Draws the volume's world-extent box as a wireframe outline, in both
renderers.
When to use it
Keep on for spatial context when sections are off or the volume is far
away; turn off for clean screenshots.
CSeismicVolume - Blend channels (Red / Green / Blue gain)
Property names: Red gain, Green gain, Blue gain (in the Blend
channels group; shown only on RGB blend volumes)
Description (in app): Brightness multiplier for this colour channel
What it does
Per-channel brightness for an RGB blend.
The three source attribute volumes map to Red, Green, Blue in tree
order; these gains scale each channel independently in the composite.
For spectral bands the property label also notes the band's frequency.
When to use it
Balance the composite when one band is systematically weaker or stronger
than the others (e.g. boost a faint high-frequency band so it reads in
the blend).
Notes
Only present when the volume is a blend. A blend renders the baked colour
composite directly, so it has no Display colour map / filter of its
own — these gains are its only colour controls.
CSeismicVolume - Filter min / Filter max
Property names: Filter min, Filter max
Description (in app): Lower / upper colour / clip bound
What it does
The low and high amplitude bounds of the colour range. Amplitudes at or
below Filter min take the bottom of the colour map, at or above
Filter max the top. Drag the handles on the histogram in the Display
pane, or type the values here.
When to use it
Set narrow around the data range to bring out subtle features; widen
to suppress noise spikes.
Notes
Defaults are derived from the index's percentiles, centred on zero for
signed data. Use Reset colour filter to return to defaults.
CSeismicVolume - Gain
Property name: Gain
Description (in app): Amplitude gain multiplier
What it does
Multiplies amplitude before clipping. A gain of 2 doubles the apparent
signal.
When to use it
Quick brightening that doesn't change the clip range. Useful for
side-by-side comparisons of two cubes at matched clip but different
visual emphasis.
CSeismicVolume - Polarity flip
Property name: Polarity flip
Description (in app): Negate amplitudes
What it does
Multiplies amplitudes by −1 before colormap lookup. Effectively swaps
"trough" and "peak" colours.
When to use it
When the file's polarity convention disagrees with your shop's
expectation (e.g. SEG positive vs reverse polarity). Visual check:
peaks on a reflector should look right.
CSeismicVolume - Opacity
Property name: Opacity
Description (in app): Section opacity (0-1)
What it does
Section alpha multiplier. 1.0 = fully opaque, 0.0 = invisible.
When to use it
Set below 1 to see other geometry (meshes, well logs) through the
section. Pair with Polarity flip / colormap choice for compositing
effects.
CSeismicVolume - Vertical scale
Property name: Vertical scale
Description (in app): Display-only Z stretch
What it does
Scales the vertical axis for display only. 1.0 means one world unit
per millisecond TWT (or per depth unit); the data itself is untouched.
Affects sections, wiggle, and the 3D volume render alike.
When to use it
A time section at 1.0 towers thousands of units over an
outcrop-scale scene; drop it to 0.1–0.05 to compress the section
to something that co-renders comfortably with models and point clouds.
Notes
Geometry-only — no texture re-bake, so changes are instant.
CSeismicVolume - AGC window (ms)
Property name: AGC window (ms)
Description (in app): Automatic gain control window; 0 = off
What it does
Rescales each sample by the ratio of the whole-trace RMS to the RMS
over a sliding window of this width, evening out amplitude decay with
depth while keeping the trace's overall level — so the existing clip
range stays meaningful. Gain is capped at 20× so dead zones can't
amplify to noise.
When to use it
Deep sections whose lower half fades out under a single clip range.
Typical values: 250–1000 ms.
Notes
Applies to sections and the wiggle overlay (both renderers); the 3D
volume render always shows raw amplitudes. Changing the window re-bakes
the visible sections in the background.
CSeismicVolume - Use Filter (hide) / Scale Colours / Reverse colours
Property names: Use Filter (hide), Scale Colours, Reverse colours
Description (in app): Hide samples outside the filter window / scale
the colour ramp to the filter window / reverse the colour ramp
What it does
Three checkboxes that govern how the colour range is applied.
- Use Filter (hide) — hides (clips out) samples outside the Filter min / max window instead of clamping them to the end colours. Use it to punch out a background band and show only the amplitudes of interest.
- Scale Colours — stretches the colour ramp across the filter window (the full map spans Filter min → Filter max) rather than across the whole data range.
- Reverse colours — flips the colour ramp end-for-end.
CSeismicVolume - Reset colour filter
Property name: Reset colour filter
Description (in app): Re-derive the colour range + default filter
window from the data
What it does
One-shot trigger. When toggled, recomputes the Filter min / max
window (and colour range) from the volume's amplitudes.
When to use it
After changing gain, or on an unfamiliar cube where the current colour
range looks washed out / saturated.
CSeismicVolume - Colour Map
Property name: Colour Map
Description (in app): Project colour map for this volume
What it does
Selects the active colour map from the project colour-map list — the
same shared list used by meshes, point clouds, and other objects — with
a preview swatch per entry. The Display pane also shows a histogram
of the volume's amplitudes with draggable filter handles (see Filter
min / Filter max).
When to use it
Change to suit the data. A sensible default is applied automatically:
Seismic for raw amplitudes, and per-attribute defaults for derived
volumes — sequential viridis for envelope / RMS / sweetness /
frequency / spectral, cyclic twilight for instantaneous phase and
azimuth, and Diverging RWB for relative impedance and curvature.
Notes
Add or edit maps in the project's Colour Maps collection; new maps appear
in this dropdown. RGB blend volumes have no colour map — they render a
baked composite (see Blend channels).
CSeismicVolume - Tile cache (MB)
Property name: Tile cache (MB)
Description (in app): Decoded-trace LRU cache budget
What it does
Sets the LRU cache budget for decoded traces, in megabytes. The cache
holds individual traces as float[samples_per_trace].
When to use it
Increase (256+ MB) for surveys with very wide sections where you scroll
back and forth, or when 3D render keeps re-decoding the same bricks.
Decrease if total memory pressure is high.
Notes
Changes apply immediately. Eviction happens until current usage fits
the new budget.
CSeismicVolume - Volume atlas (MB)
Property name: Volume atlas (MB)
Description (in app): GPU brick atlas budget for 3D rendering
What it does
Sets the size of the GPU atlas that holds 64³ bricks during 3D
rendering. The atlas dimensions are rounded down to whole bricks per
axis and capped to the brick grid extent.
When to use it
Larger atlas = more of the cube resident on the GPU = less paging
during pan. 512 MB (default) suits typical 1024² cubes; bump to 2 GB
for very large cubes if your GPU has the headroom.
Notes
Changes set an atlas dirty flag; the atlas is rebuilt on the next
3D render. Until then, the existing atlas continues to serve at the
old size.
CSeismicVolume - Bricks per frame
Property name: Bricks per frame
Description (in app): Cap on per-frame brick uploads
What it does
Limits how many 64³ bricks (1 MB each at R32F) the renderer uploads per
frame. Higher values fill the atlas faster after enabling 3D, at the
cost of frame stutter while uploading.
When to use it
Raise to 8–16 if you don't mind stutter and want fast fill. Lower
to 1–2 if pan/zoom feels jerky during heavy paging.
CSeismicVolume - Linear atlas filter
Property name: Linear atlas filter
Description (in app): GL_LINEAR (smooth, slight bleed) vs
GL_NEAREST (blocky, exact)
What it does
Toggles the texture filter on the brick atlas. On gives smooth
trilinear sampling, with the side-effect that ray samples at brick
boundaries interpolate against neighbouring (unrelated) atlas slots,
producing 1-voxel-wide stripes. Off uses nearest-neighbour for
exact, blocky rendering.
When to use it
Off if you find the brick-edge stripes objectionable; on otherwise.
Notes
Toggling triggers an atlas rebuild on the next 3D render.
CSeismicVolume - Tile cache (Diagnostics)
Property name: Tile cache (Diagnostics group)
Description (in app): Read-only readout of tile cache usage
What it does
Shows <used> / <budget> MB (<count> traces) for the current tile
cache state.
CSeismicVolume - Brick atlas (Diagnostics)
Property name: Brick atlas (Diagnostics group)
Description (in app): Read-only readout of GPU brick atlas usage
What it does
Shows <resident> / <total slots> (<voxel dims>) so you can see how
many 64³ bricks the atlas currently holds.
CSeismicVolume - Brick grid (Diagnostics)
Property name: Brick grid (Diagnostics group)
Description (in app): Read-only readout of brick grid extents
What it does
Shows the brick-grid dimensions (e.g. 16x16x32 for a 1024×1024×2000
cube).
CSeismicVolume - Pre-stack fold (Diagnostics)
Property name: Pre-stack fold (Diagnostics group)
Description (in app): Traces per cell for pre-stack files
What it does
Shows N traces/cell (brute-stacked on read) when the scan detected
more than one trace per (inline, crossline) cell — a pre-stack gather
file. Absent for post-stack files.
When to use it
Confirms why the Gather trace control appeared, and what the maximum
selectable trace number is.
CSeismicVolume - Indexed traces / Amplitudes (Diagnostics)
Property names: Indexed traces, Amplitudes (Diagnostics group)
Description (in app): Read-only stats from the sidecar
What it does
Shows total trace count and the amplitude [min, max] plus p1 / p99
percentiles. Use to confirm the scan saw what you expected.
CSeismicVolume - Clear tile cache
Property name: Clear tile cache
Description (in app): Drop every cached trace
What it does
One-shot trigger. Toggling clears the tile cache. The next section /
brick read pulls fresh from disk.
When to use it
After modifying the underlying SEG-Y file externally (rare); to free
memory for another task without losing the volume.
CSeismicVolume - Last pick (Inline / Crossline / Sample / Amplitude / World)
Property names: Inline, Crossline, Sample, Amplitude,
World (in Last pick group)
Description (in app): Read-only info from the most recent ray-pick
What it does
Shows the inline number, crossline number, sample index, amplitude,
and world position of the most recent click on a section in the 3D
view.
When to use it
Read-out for QC and amplitude inspection at a specific point.
Notes
Refresh by clicking the volume in the tree after picking. Picks
against time-slices, inlines, and crosslines are all reported through
the same group.