Skip to main content

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, 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), 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.

When to use it
First thing to try when geometry parses incorrectly.

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 - 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. Defaults to the centre on first bind.

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.

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 3D ray-marched rendering of the entire cube. Bricks page in over several frames, prioritised front-to-back relative to the camera.

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
First-time toggle on a large cube is slow as the atlas fills up; once populated, panning is responsive. Disabling the toggle frees the GPU atlas memory.

CSeismicVolume - Clip min / Clip max​

Property names: Clip min, Clip max
Description (in app): Lower / upper amplitude clip

What it does
Amplitudes at or below Clip min map to the bottom of the colormap; at or above Clip max to the top. Linear in between.

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 p1 / p99 percentiles, centred on zero. Use Reset clip to amplitudes 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 - Reset clip to amplitudes​

Property name: Reset clip to amplitudes
Description (in app): Re-derive clip min/max from the index p01/p99 percentiles

What it does
One-shot trigger. When toggled, recomputes Clip min / Clip max as ±max(|p01|, |p99|) so the clip is symmetric around zero and brackets 99% of indexed amplitudes.

When to use it
After changing gain or hitting an unfamiliar cube where the current clip looks washed out / saturated.

CSeismicVolume - Colormap​

Property name: Colormap
Description (in app): Built-in colormap selection

What it does
Dropdown for the active colormap. Options:

  • Diverging RWB (default) — blue → white → red, centred at the clip midpoint. Standard for signed amplitudes.
  • Grayscale — linear black to white. Classic interpretation aid.
  • Seismic — gray midband with red/blue clip-tail emphasis.
  • Viridis — perceptually uniform; good for absolute-value attributes.

Notes
The colormap texture is rebuilt on the GL thread the next time the volume draws.

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 - 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.