RESOLVE FX · CONTROL THE VECTOR
Directional Blur.
Set the direction.
Then decide the trail.
From restrained motion-like smear to graphic RGB streaks. Understand Angle, Strength, Realistic/Stylized, Symmetry, channels and frame edges — then animate only the controls that match the motion.
Strength + Angle
Type + Symmetry
Channels + Border
Use the vector chart in the lab: rotate Angle first, then increase demo length. Switch Symmetric off to see why direction and distribution are different decisions.
INPUTDIRECTIONALChannels and alpha in the model
Unequal RGB values change streak amount per channel along the same angle. This lab does not reproduce Resolve’s OFX sampling or numeric Strength mapping.
Teaching model, not Resolve: “length” is a demo pixel distance, not Blur Strength. Realistic/Stylized are illustrative weighting profiles only; Resolve’s exact OFX kernel, color management, motion integration and parameter scaling are not reproduced.
Actual Resolve interface captures + an explicitly synthetic teaching model.
11 controls · 4 exercises01THE DIRECTIONAL MODEL
One angle creates the geometry. The other controls shape its character.
Directional Blur is conceptually simpler than depth- or lens-aware effects, but that simplicity makes wrong direction, symmetry and edge handling immediately visible.
A vector: amount × angle
Directional Blur does not spread softness equally in every direction. It stretches detail along one direction: Blur Angle sets the orientation and Blur Strength determines how visible the smear becomes. That is why the right angle usually matters more than a large amount.
Profile and symmetry are separate decisions
Realistic and Stylized change blur character, while Symmetric Blur changes how the smear is distributed around the source detail. With symmetry off the streak extends mainly in one direction; with it on, blur is distributed both ways and can become double-image-like sooner at high strength.
Channels, edges and Blend decide technical cleanliness
Channel Adjustment can keep RGB neutral or deliberately separate the length of color streaks. Border Type matters when the sampling path reaches outside the frame, Blur Alpha determines whether transparency is blurred, and Global Blend is the final mix after the structure is already right.
Parameter semantics: Blackmagic Design · DaVinci Resolve 21.1 Manual / Resolve FX Blur ↗
02THE ACTUAL CONTROLS
Eleven controls, four distinct decisions.
The detail screenshots are actual Directional Blur interface captures from the archive. Values shown are examples of the captured states, not claimed defaults or universal settings.
Streak geometry
Set direction and character first.
- Blur Strength
Overall directional blur amount. In practice it is the primary control for streak length/visibility; its numeric scale belongs to Resolve, so do not translate the value into pixels or a shutter setting.
CheckRaise it after Angle is established. Excessive strength quickly destroys contours, text and faces, especially with Symmetric Blur.
- Blur Angle
Direction of the blur in the frame. For a motion-like result, follow the actual subject trajectory, camera pan or dominant compositional diagonal rather than choosing a convenient round number.
CheckCheck sign and direction across several moving frames: visually similar +45° and −45° send the streak along different diagonals.
- Blur Type
The manual describes Realistic as emulating photographic motion blur and Stylized as a simple smooth digital blur. It is not a low/high-quality switch; it is a character choice.
CheckCompare modes at the same Strength and Angle. If everything changes at once, you cannot tell which decision improved the shot.
- Symmetric Blur
When enabled, blur is created in both directions along the chosen angle; when disabled, it extends in one direction from the original position. Blackmagic notes that the symmetric version can feel more camera-motion-like and can become a blurred double image.
CheckIf the subject unexpectedly looks doubled, do not reset the whole effect: compare Symmetric Blur off and a lower Strength first.
Per-channel control
Equal values keep the smear neutral.
- Red
Blur-strength multiplier for the red channel relative to overall Blur Strength. A value of 1.000 means a neutral contribution relative to the base amount, not “100% red color”.
CheckA different Red value is useful for deliberate color dispersion. On neutral edges, accidental separation reads as a technical mistake.
- Green
Directional-blur multiplier for Green. In a neutral setup it normally matches Red and Blue.
CheckInspect white titles, fine contours and high-contrast edges; channel mismatches show up there first.
- Blue
Blur-strength multiplier for the blue channel. Unequal RGB values can create colored tails along the same geometry because channel amount changes, not each channel’s angle.
CheckFor stylization, keep the difference controlled and judge it in motion: a long blue tail can quickly become more visible than the subject.
- Alpha
Blur-strength multiplier for the alpha channel relative to overall Strength. It works together with Blur Alpha; the multiplier does not replace the switch that enables alpha blurring.
CheckOn ordinary opaque footage the difference may be invisible. Test on keyed/transparent elements and in the actual composite.
Edges and transparency
A long streak reaches the frame edge quickly.
- Border Type
Defines how missing data is supplied when the blur path extends outside the frame. The Resolve manual lists Black, Replicate, Reflect and Wrap Around. Differences appear primarily near frame edges, not in the middle of the image.
CheckAt high Strength, inspect a frame where the subject nearly touches an edge. Look for black contamination, reflected content, replicated edge pixels or material wrapping from the opposite side.
- Blur Alpha
Includes the alpha channel in the blur along with image content. This matters for graphics, keyed footage and other elements with transparency.
CheckIf blur leaves a hard or unexpected transparency edge, compare Blur Alpha states and inspect premultiplication/compositing, not RGB alone.
Final mix
Mix a finished effect; do not repair geometry with it.
- Blend
Global Blend mixes the completed Directional Blur with the node’s unaffected result. It is a useful final dry/wet after Strength, Angle, Type, Symmetry, channels and edge behavior are already correct.
CheckIf the streak points the wrong way or doubles the subject, lowering Blend only hides the cause. Fix geometry first, then mix.
03WHEN THE STREAK LEAVES THE FRAME
Border Type answers a missing-pixels question.
A long directional path reaches outside the image sooner than a compact blur. The middle of the frame can look identical while the edge fails completely.
Black
… ABC | ···Outside-frame samples effectively provide no useful picture, so a strong streak near the border can pull in darkness.
Useful for revealing the edge problem clearly; usually requires deliberate intent when important detail touches the border.
Replicate
AAA | ABC | CCCExtends the image using the nearest edge pixel. It often avoids black contamination but a long streak can stretch the edge color into a stripe.
Inspect clean bright edges and backgrounds for an obvious solid-color band.
Reflect
CBA | ABC | CBAReflects image content across the border. It often looks natural on organic footage, but near recognizable objects it can create an obvious mirrored duplicate.
Check faces, text and straight lines near the edge; reflections reveal themselves there first.
Wrap Around
BCA | ABC | ABCUses content from the opposite frame edge. It can suit cyclic or graphic designs, but on ordinary footage it can pull unrelated detail across the border.
Inspect left and right edges together for content that has no physical reason to appear there.
The letter strings are explanatory edge-extension diagrams, not literal Resolve pixels. The actual screenshot shows Reflect selected in a closed menu; the four available modes come from the Resolve manual.
04FROM SIGNAL TO STREAK
Keep the vector blur isolated and easy to bypass.
A directional effect is easier to diagnose when primary correction, localization and the FX itself are not mixed into one opaque step.
The isolated vector-blur node
Apply Directional Blur here and constrain it with a tracked Power Window, Magic Mask or another matte when the streak should affect only part of the frame. Set Angle first, then Strength, Type/Symmetry and edges.
Green lines show image flow. The dashed matte annotation is not a separate signal node. For an animated speed accent, keyframe Strength (and Angle only when direction changes) on the FX node. This is a teaching diagram, not a Resolve screenshot.
Related Color workflow: node pipeline ↗ · Power Windows / Tracker ↗
05BUILD IT IN RESOLVE
Four exercises reveal four different failure modes.
These are practical teaching exercises, not one-click presets. Use your own footage and accept the result by what the shot does in motion.
Accent a real motion vector
Add a motion-like directional streak to a moving subject without turning the whole frame into a transition.
PrepareUse a clip with a clear subject trajectory or camera pan. Create a dedicated Color node for the FX and localize it with a Power Window/Magic Mask if needed.
- 01
On a frame with strong motion, set Blur Angle to the actual trajectory first.
- 02
Choose Realistic and start with modest Blur Strength. Compare Symmetric on/off; the result should support motion rather than create random doubling.
- 03
Keep RGB at 1.000, check Border Type on edge frames and verify Blur Alpha if transparency is involved.
- 04
If speed changes, animate Strength with the motion; use Blend for the final amount.
The streak follows motion across adjacent frames, the subject remains readable and no obvious edge artifacts appear.
Build a whip / speed transition
Use Directional Blur as a controlled blur peak around an edit or fast pan.
PrepareUse two adjacent shots with compatible motion direction or a deliberately created whip pan. Keep the FX isolated on a dedicated node/adjustment layer according to your workflow.
- 01
Align Angle with the dominant transition direction and compare Realistic with Stylized.
- 02
Keep Strength low before acceleration, raise it toward the cut, then bring it back down afterward.
- 03
For a one-sided streak, test Symmetric off and the sign of Angle; for a two-sided smear, test Symmetric on.
- 04
Watch the transition in real time and in a short export; a still frame cannot reveal keyframe timing.
The blur peak is tied to speed and the cut, the ramp in/out feels smooth, and frame edges do not reveal the chosen Border Type.
Create a controlled RGB streak
Create graphic color separation along one direction without separate angles for each channel.
PrepareUse a high-contrast subject or title on a clean background where colored tails are easy to evaluate.
- 01
First establish a neutral Directional Blur with RGB = 1.000 and suitable Angle / Strength.
- 02
Offset Red, Green and Blue slightly. Change one channel at a time so its contribution is obvious.
- 03
Do not use Blend to fix one overly long color tail; correct that channel multiplier.
- 04
Inspect white and gray detail; the colored fringe should read as design, not an accidental defect.
Colored tails are controlled, share one Angle and do not turn neutral detail into messy chromatic doubling.
Keep the streak in the background only
Add directional energy to the background while keeping a face, product or primary subject sharp.
PrepareUse a shot with a separable main subject. Prepare a tracked Window/Magic Mask or an inverted background matte on the FX node.
- 01
Set Angle from the composition or background motion at moderate Strength.
- 02
Restrict the FX with a matte and track it across the whole shot before fine-tuning blur.
- 03
Check matte feathering in motion; strong Directional Blur exposes mask errors more readily than ordinary soft blur.
- 04
Use Blend only after the matte, Angle and Border Type hold up throughout the shot.
The primary subject stays clean, the background gains a directional streak and the matte boundary is not visible in motion.
06CHOOSE THE RIGHT GEOMETRY
Directional Blur is for a vector, not every kind of softness.
| FX | What shapes the result | Explore it for |
|---|---|---|
| Directional Blur | One controlled angle + Strength, with Realistic/Stylized, Symmetry and per-channel amount. | Motion-like streaks, whips, directional styling and local smears. |
| Box Blur ↗ | H/V blur with split axes, per-axis channels and Iterations. | When independent horizontal/vertical softness and repeated box passes matter more than one vector. |
| Gaussian Blur ↗ | Smooth soft blur with independent H/V amount and channels. | General detail/noise softening without an obvious directional streak. |
| Radial Blur ↗ | Blur rotates around a Center Position with its own symmetry controls. | Spin/rotation, rotational energy and center-based transitions. |
| Zoom Blur ↗ | Streaks converge/diverge around a chosen center. | Camera push/pull impression and radial speed accents. |
| Lens Blur ↗ | Optical-style defocus shaped by aperture/bokeh rather than a motion vector. | When defocus character and bokeh matter rather than a movement trail. |
07DIAGNOSE THE VECTOR
Most failures point to one specific control family.
01The streak follows the wrong diagonal+
Check Blur Angle and its sign on a frame with obvious motion. Do not compensate for the wrong direction with Strength or Blend; neither changes geometry.
02The subject looks doubled+
A common cause is high Strength with Symmetric Blur distributing the image both ways. Compare Symmetric off and reduce Strength until the streak supports motion instead of duplicating the contour.
03The tail extends from the wrong side of the subject+
With Symmetric off, one-sided streak direction depends on Angle. Reverse/rotate Angle; enabling Symmetric creates blur on both sides and is not the same solution.
04Unexpected colored edges appear+
Check Red, Green and Blue. Unequal Channel Adjustment deliberately gives channels different blur amounts; for a neutral result restore equal values, typically 1.000 in the captured default-like state.
05A black strip or unrelated content appears at the frame edge+
This is a classic Border Type symptom. Compare Black, Replicate, Reflect and Wrap Around on the same frame; choose based on edge content rather than habit.
06RGB is soft but transparency stays hard+
Check Blur Alpha and the Alpha multiplier. For graphics/keys, judge the real composite as premultiplication and downstream nodes can also affect the edge.
07The geometry is right but the effect is too obvious+
Keep Angle/Type/Symmetry intact and use Global Blend as the final dry/wet. If the streak itself is too long, lowering Strength is the more direct fix.
08The blur animation jerks through a transition+
Inspect Strength/Angle keyframes and their curves, plus matte tracking. Direction should not unexpectedly interpolate through an unwanted path between angles; evaluate motion, not keyframes in isolation.
Keyframes: animate the cause, not only Blend
For a speed ramp or whip, tie Strength to actual speed first. Animate Angle only when motion direction changes. Blend is useful for bringing the FX in/out but does not replace the correct trajectory.
Node order: the effect should be easy to bypass
Keep base balancing separate from Directional Blur. It is practical to manage the local matte and tracking on the FX node; final grain/sharpening is usually easier to judge after the blur is established. This is a workflow example, not a mandatory rule for every grade.
Judge motion and the delivery render
A directional streak can look convincing on a still and fail in playback. Watch the full shot, then a short target-resolution export; edge handling, alpha and animation timing are easier to judge there.
08BEFORE YOU DELIVER
Check the motion path, not only the panel.
The checklist is a reminder, not automated certification. Watch the shot through its fastest motion and through the frame edges.
09QUESTIONS THAT MATTER
Keep geometry, character and mixing separate.
What does Directional Blur do in DaVinci Resolve?
It is a blur constrained to a single angle. Blur Strength controls overall amount and Blur Angle controls direction; Blur Type, Symmetric Blur, channel multipliers, Border Type, Blur Alpha and Blend refine character and technical behavior.
Is Realistic better than Stylized?
No. Blackmagic describes Realistic as emulating photographic motion blur and Stylized as a simple smooth digital blur. They are different styles, not quality tiers.
What exactly does Symmetric Blur do?
It distributes directional blur in both directions along Angle. With it off, the streak extends in one direction from the original position. At high Strength, the symmetric mode can produce a blurred double-image effect sooner.
Can RGB channels use different angles?
Not with these controls. Red, Green and Blue scale blur amount relative to overall Strength while sharing one Blur Angle, so they change colored streak length/intensity along the same geometry.
Which Border Type should I choose?
There is no universal choice. Black can pull in darkness, Replicate stretches the edge, Reflect mirrors it and Wrap Around uses the opposite edge. Compare them on the actual frame with strong Strength near the border.
Does Directional Blur replace real camera motion blur?
No. It is a controllable post effect and a useful creative tool. It can create a motion-like streak but does not reconstruct physically accurate shutter exposure, per-object trajectories, occlusion or temporal motion integration.
Directional Blur or Box Blur?
Choose Directional Blur when direction is part of the task: one Angle, a streak, whip or motion accent. Box Blur is more useful when independent H/V axes, Split and Iterations matter without one motion vector.
Sources and the scope of this guide
Visible control names and values were checked against the actual site screenshot. Control semantics and Border Type options were cross-checked against Blackmagic Design’s current DaVinci Resolve 21.1 documentation. The interactive lab is an independent teaching model and does not claim Resolve’s internal OFX algorithm or Strength scale.
Exercises have not been certified by a live Resolve render in this web update. Edition availability and small UI differences should always be checked in the installed build used for production.