Hot Spot Node

Hot Spot is a parametric lens flare generator built into Fusion. With its 3 Lens Reflect tabs, it can create ghosts (secondary reflections spread along a straight line through the main hot spot and the center of the image) - the characteristic behavior of real photographic flares.

For pro lens flares, tools like Optical Flares (Video Copilot) or Knoll Light Factory are richer, but Hot Spot remains useful and native for quick or stylized flares.

• Effects Library: Tools > Effect > Hot Spot
• Quick add: right-click in the Node Editor → Add Tool > Effect > Hot Spot

• Image Input (orange) - the primary image.
• Effect Mask (blue) - optional. Limits the hot spot to an area.
• Occlusion (green) - optional. An image that blocks the hot spot: white pixels = full occlusion, gray = partial. Crucial so the flare disappears when an object passes in front of the source (person, building, etc.).

Sun lens flare:
MediaIn → Hot Spot (Center = sun position, Add mode) → MediaOut

With occlusion (an object hiding the flare):
MediaIn → Hot Spot ← Occlusion (alpha of the character)
           ↓
         MediaOut

Dramatic spotlight:
Full black → Hot Spot (Multiply mode, Center on the subject) → Merge Screen over MediaIn

Primary Center (X / Y)

Position of the main hot spot. A crosshair in the viewer for direct placement. Animate it to simulate a flare that follows the sun.

Hot Spot Size

Diameter of the hot spot. 1.0 = the full width of the image. Typical values 0.1-0.3.

Aspect

Aspect ratio. 1.0 = a perfect circle. > 1.0 = horizontal stretch (anamorphic look). < 1.0 = vertical stretch.

Primary Strength

Brightness of the main hot spot.

Secondary Strength

Intensity of a secondary reflection diametrically opposite the main hot spot.

Aspect Angle

Rotation of the effect (useful when Aspect ≠ 1).

Lens Aberration

Type of chromatic aberration: In/Out modes, Flare In/Out, or Lens mode. Simulates real optical flaws.

Add (Burn)

Adds the brightness of the hot spot to the image. Makes the affected areas brighter (dodge effect). The most common mode for a classic lens flare.

Subtract (Dodge)

Darkens the image in the hot spot area. Less intuitive, for artistic use.

Multiply (Spotlight)

Spotlight effect: the hot spot keeps its brightness and the rest of the image is darkened proportionally. Perfect for an inverse vignette (light up only one area, keep the rest in shadow).

Color Tab

Adjustments through a color spline across the radius of the hot spot. Lets you define a complex gradient from the center to the edges. Can be animated for hot spots that change hue.

Radial Tab

Creates patterns around the circumference of the hot spot. Lines, polygons, motifs. Simulates a visible lens aperture.

Three Lens Reflect 1, 2, 3 tabs let you add up to 3 secondary reflections, each with its own settings:

• Shape: circular, NGon star, polygon. The NGon shape gives the characteristic "aperture" reflections.
• Size: size of each reflection.
• Color: a specific tint (real reflections often have different colors).
• Position on the axis: the reflections sit on the straight line through the main hot spot and the center of the image (the real optical behavior of actual flares).

Tip: vary the 3 reflections with different sizes and colors → a flare that looks "photographic" rather than "generated".

• Sun lens flare - Center on the sun position, Add mode, Primary Size 0.3, 2-3 active Lens Reflects = a classic sun flare.
• Tracked hot spot - connect the Center to a Tracker that follows the sun in the shot = a flare that follows perfectly even when the camera moves.
• Occluded flare - a character walking in front of the sun → roto the character → Occlusion input = a flare that disappears when the person covers the sun. Photographic realism.
• Dramatic spotlight - Multiply mode, large Size, centered on the subject = a theatrical spotlight / cinematic noir effect.
• Custom radial vignette - Multiply mode with a very large Size and a moderate Primary Strength = a custom vignette, more flexible than a preset vignette.
• Animated burst of light - animate Primary Strength 0 → 1 over a few frames = a one-off flash (a hit landing, a burst of light).
• Sci-fi: hologram / energy portal - Hot Spot with a cyan blue Color Tab + several Lens Reflects = a radiant energy core.

• Occlusion is a must for believability - without occlusion, the flare stays in front of characters passing in the foreground. An instant "fake" look.
• Vary the 3 Lens Reflects - same size + same color = too regular. Sizes 0.05, 0.08, 0.12 with different tints = natural.
• NGon star shapes - hexagonal (6 points) to mimic a 6-blade aperture, typical of "cine" lenses.
• Hot Spot for a fake sun - a shot with no visible sun, a Hot Spot placed at the edge of the frame = you "sense" a powerful light source on the left / right.
• Avoid overdoing it - the lens flare has become a cliché. A subtle flare (Primary Strength 0.3-0.5) is more cinematic than an overwhelming Hollywood flare.
• Animate the Center with very subtle jitter to simulate handheld camera shake. A flare that "lives" a little.
• For an ultra-realistic pro render, use stock lens flares instead (HDR images of real scanned flares) merged in Screen over the shot. Hot Spot remains useful for quick prototyping or stylized looks.