RadialBlur

The core model is rotational motion blur around a chosen pivot. Blackmagic describes Radial Blur as simulating the motion blur that would occur if the image were spinning around its center point, so the defining visual cue is an arc around Center Position rather than a straight radial streak.

Do not confuse RadialBlur with ZoomBlur. ZoomBlur produces streaks that travel toward or away from a center, while RadialBlur smears detail along circular paths around a pivot. Both can look 'radial' on abstract imagery, but their motion geometry is different.

RadialBlur is also not the Krokodove Radial node. Radial is a coordinate warp/dent that repositions pixels relative to Center. RadialBlur accumulates samples along rotational motion and behaves as a blur rather than a geometric dent.

Smooth Strength controls how much rotational smear is applied. The captured Resolve Inspector shows 0.4, but that is an example state rather than a universal preset. A reliable setup starts with a small amount, proves the pivot and direction, then increases Strength until the arcs read clearly.

Blur Type exposes Stylized and Realistic. Blackmagic documents Realistic as a photographic motion-blur model and Stylized as a simpler, smooth digital blur. This is a change of blur model, not a draft-versus-final quality switch.

Blur Symmetry provides three modes. Symmetric creates blur in both directions and produces a double-image-like arc around X/Y Position. Clockwise leaves a one-direction clockwise trail; Anticlockwise leaves a one-direction counter-clockwise trail.

Center Position X/Y defines the rotational pivot. The captured baseline is 0.5/0.5. When Center matches the actual pivot of a rotating object, the blur feels physically coherent; moving Center off-axis changes every blur trajectory without translating the source like a Transform node.

Center Position changes blur geometry, not source placement. On a grid, original landmarks stay in their normal source coordinates while the smeared samples curve around the new pivot. That makes a grid or circular logo an excellent diagnostic source.

Channel Adjustment contains separate Red, Green, Blue and Alpha controls. Blackmagic defines them as the blur strength of a specific channel relative to the overall blur. The captured 1.0/1.0/1.0/1.0 state is a neutral baseline with equal channel participation.

Tune Channel Adjustment after the motion geometry. If Center, Symmetry, Strength and RGB weighting all change at once, it becomes difficult to tell whether a colored fringe comes from deliberate channel separation or from a bad pivot and excessive blur.

Alpha Channel Adjustment matters on Text+, PNG logos and any transparent graphic. RGB can look acceptable while the alpha edge carries a longer or mismatched trail, so inspect Alpha Viewer separately on premultiplied elements.

Quality offers Faster, Better and Enhanced. Blackmagic notes that Better and Enhanced are intended to improve sharp image content at low blur values; if that condition does not apply, Faster may look just as good. Quality is therefore a quality/performance decision, not an automatic draft-to-final ladder.

Compare Quality modes on the same representative frame with Center, Type, Symmetry and Strength fixed. Fine lines and sharp edges at moderate blur are more revealing than already-soft footage. If no visual benefit is visible, do not assume one from the label alone.

Border Type controls samples beyond the source raster. The captured menu contains Black, Replicate, Reflect and Wrap-Around. The mode becomes important when a blur arc reaches outside the source image.

Black makes missing external pixels obvious, Replicate extends the boundary pixels, Reflect mirrors the edge, and Wrap-Around samples the opposite side. None of these modes corrects a wrong Center or excessive Strength; they solve boundary behavior only.

Move With Sizing handles coordinate consistency. Blackmagic describes it as retaining the blur center's relative position when Input or Edit sizing changes. If an upstream resize or sizing operation moves the apparent pivot, compare the flag on and off before compensating with animated Center values.

This article keeps the reviewed topology conservative: one Image input and one Output. It does not invent a second image input or Effect Mask socket by analogy with other OpenFX tools. If spatial isolation is needed, build it with a separately verified mask/composite workflow.

For animation, prove the static geometry on one frame first. Then keyframe Smooth Strength, Center Position, or both. The midpoint matters more than just the start and end because long arcs, boundary repetition and sizing drift often appear only near peak blur.

Strong RadialBlur can destroy legibility on logos and UI. A short Strength peak around maximum angular velocity often reads better than continuous heavy blur. For persistent rotational motion, the blur should support the motion rather than erase the object's identity.

A reliable diagnostic order is Center → Type/Symmetry → Strength → Channels → Quality → Border → Move With Sizing. This keeps motion geometry, channel styling, sampling quality and edge handling as separate decisions.