Description

Velocity Brush 3D is an interactive tool for hand-editing a depth-domain 3D velocity model directly on screen, in the same way you would retouch an image with a paint brush. It shows the volume as three linked views – an inline section, a crossline section and a depth (map) slice – and lets you locally raise, lower or reset the velocity in a small 3D region around the cursor by clicking or dragging. Use it whenever an automatically built velocity model (from tomography, migration velocity analysis, well calibration, etc.) contains a localized error, artifact or geologically implausible zone that is easier to fix by eye than to re-run through an automatic algorithm.

Click on any of the three views to apply a single brush dab at that location, or press and drag the mouse to sweep the brush along a stroke; a translucent ellipse with a small cross-hair previews the true 3D footprint of the brush on all three views as you move the cursor, so you can see in advance how far an edit will reach along inline, crossline and depth. Every stroke is recorded so that pressing Ctrl+Z immediately undoes the last stroke, up to five strokes back.

Input data

Input gather

The 3D depth-domain velocity model to be edited, gridded on a regular inline/crossline bin pattern. This volume is the tool's untouched reference: it is used to build the inline, crossline and depth slice views you paint on, and it is also the baseline against which the "Maximum relative change" safety limit is measured, so that no edit can push a sample too far from its original value.

Parameters

Velocity brush visualization parameters

Selected inline

Sets which inline number is currently displayed and painted on in the inline view. You can type a value here to jump straight to a specific inline instead of scrolling through the volume; the value is automatically clamped to the inline range actually present in the input model. It also updates automatically whenever you finish a brush stroke on the crossline view with "Select orthogonal section on click" turned on.

Default: 0. Change it to move the inline view to a particular line of interest before you start painting.

Selected crossline

Sets which crossline number is currently displayed and painted on in the crossline view, working the same way as "Selected inline" but for the orthogonal direction. It is clamped to the crossline range of the input model and updates automatically after a stroke on the inline view when "Select orthogonal section on click" is enabled.

Default: 0. Change it to move the crossline view to a particular line of interest before you start painting.

Selected depth slice

Sets the depth, in metres, of the horizontal map-view slice shown at the bottom of the three linked views. The entered value is automatically snapped to the nearest depth sample of the input model. Use this to move the map view to the depth of a known problem zone (for example, a velocity pull-up or push-down around a channel or salt body) before brushing it out.

Default: 0 m (top of the model).

Brush parameters

Work mode

Chooses how the brush changes velocity values under the cursor. In "Relative" mode each stroke nudges the existing velocity up or down by a percentage of its current value, which is the safest choice for gentle corrections because the result always stays close to what was already there. In "Constant" mode each stroke instead blends the velocity toward a fixed target value ("Desired velocity"), which is useful for flattening a clearly wrong zone to a known, correct velocity. Switching this option changes which of the parameters below are shown.

Default: Relative. Options: Relative, Constant.

Brush percentage (+ increase, - decrease)

Only used in "Relative" work mode. Sets how much the velocity changes at the very centre of a full-strength brush stroke, expressed as a fraction of the current value: a positive value raises the velocity, a negative value lowers it, and the change fades to zero towards the edge of the brush footprint. For example, a value of 0.1 raises the centre of the stroke by about 10%.

Default: 0.1 (about +10% per stroke). Use small values and repeat the stroke for a gradual, controlled correction; use larger values for a faster, more aggressive change.

Maximum relative change

Only used in "Relative" work mode. Acts as a safety guard rail: no matter how many times you brush over the same point, the resulting velocity can never end up more than this fraction above or below the value it had in the original input model. This prevents repeated strokes from accidentally driving a velocity to an unrealistic value.

Default: 0.2 (±20%), minimum 0. Tighten this if you want to strictly limit how far edits can drift from the original model; loosen it if you need to make a larger correction in one area.

Desired velocity

Only used in "Constant" work mode. Sets the target velocity that brushed samples are pulled towards; at the centre of a full-strength stroke the sample is set fully to this value, fading back to the original value towards the edge of the brush. Use this when you know the correct velocity for a zone (for example from a well log or a regional trend) and want to paint it directly into the model.

Default: 2000 m/s. Valid range 0-20000 m/s, adjustable in steps of 100 m/s.

Harshness (0=soft, 1=hard)

Controls how the brush's strength fades from its centre to its edge, exactly like the hardness setting of a paint brush in an image editor. Low values (soft brush) apply the full effect only at the very centre and blend smoothly out to nothing at the edge of the footprint, which is best for natural-looking, gradual corrections that blend into the surrounding model. A value of 1 (hard brush) applies the full effect uniformly everywhere inside the brush footprint with an abrupt edge, which is useful for cutting a sharply bounded artifact out of the model.

Default: 0.1 (mostly soft). Valid range 0.0-1.0.

Brush radius along inline

Sets, in metres, how far the brush reaches sideways across neighboring crosslines from the point you click, i.e. how wide the brush footprint appears when you paint on the inline view. Increase it to affect a wider swath of the model with each stroke, or decrease it for fine, localized edits.

Default: 1000 m, minimum 0.

Brush radius along crossline

Sets, in metres, how far the brush reaches sideways across neighboring inlines from the point you click, i.e. how wide the brush footprint appears when you paint on the crossline view. Together with "Brush radius along inline" and "Brush radius along depth" it defines the ellipsoidal 3D shape of every stroke.

Default: 1000 m, minimum 0.

Brush radius along depth

Sets, in metres, how far the brush reaches above and below the depth you click, i.e. the vertical thickness of the brush footprint. Reduce it to keep an edit confined to a thin interval; increase it to smooth or correct velocity through a thicker zone in one stroke.

Default: 1000 m, minimum 0.

Select orthogonal section on click

When enabled, finishing a stroke on the inline view automatically moves the crossline view to the crossline under your cursor (and finishing a stroke on the crossline view automatically moves the inline view), so the two vertical sections keep following where you are working. Turn it off if you want the two sections to stay fixed on the lines you originally chose while you brush.

Default: On.

Performance

Update brush projection on all three slices

When enabled, the brush outline (the preview ellipse and cross-hair) redraws on the inline, crossline and depth views at the same time whenever you move the cursor, so you can always see the full 3D footprint of the brush. Turning it off updates the outline only on the view you are actively working in, which can make the tool more responsive when the volume is large.

Default: On.

Output data

Output gather

The edited 3D velocity model, updated live after every brush stroke. It starts out as an exact copy of the input model and is modified only inside the footprint of each stroke you paint, leaving the rest of the volume untouched. Connect this output to the next step of your velocity model-building or depth-imaging flow to continue working with your hand-edited velocities.

Velocity after brush editing

A second copy of the same edited velocity volume as the Output gather, provided as its own output item. Use it if you need to feed the brushed velocity model into another branch of the processing flow independently of the main Output gather connection.