Automatic Flare Positioning

Automatic Flare Positioning allows the plugin to generate and place a large number of flares directly from image data. When an HDR image is provided, the plugin analyzes its brightness and automatically spawns lights at the brightest regions of the image.

This workflow is especially useful for complex scenes where manually placing many lights would be impractical.

Drive Input

The Drive input is the image used to generate pixel-driven flares.

Because flare position and intensity are derived directly from pixel brightness and color, preprocessing the input image can significantly improve results.

Common adjustments include:

Applying gamma correction to balance flare intensities
Adding a slight blur to stabilize highlights and reduce flicker
Adjusting saturation to control color variation in the flares

These operations are typically done upstream, before connecting the image to the plugin.

Pixel-Driven Flare Parameters

When pixel-driven flares are enabled, the plugin performs the following steps:

Bright regions are isolated using the Pixel Threshold
Each bright region spawns a light source
Lights are sorted by brightness
The brightest lights are kept, up to Max Lights To Render

The strength of each light is computed from the weighted brightness of its region.

Because HDR images can contain extremely high values, flare intensity may not match expectations at first. Use Light Brightness Multiplier to scale the result.

Example: If a bright area contains pixel values around 1000.0, the resulting light strength is derived from that value multiplied by the Light Brightness Multiplier and an internal constant.

Threshold to Render Only Starburst

After light strengths are computed, the Threshold To Render Only Starburst parameter determines whether a light renders full ghosts or only the starburst.

Lights below the threshold render starburst only
Brighter lights render ghosts and starburst

This is an important optimization, as ghost rendering is significantly more expensive than starburst rendering.

Light Size Blur Multiplier

Highlight areas in the drive image can vary greatly in size. To account for this, the plugin can apply blur to flares based on the detected highlight area.

The Light Size Blur Multiplier controls how much blur is applied:

Larger highlight areas produce softer flares
Smaller highlights remain sharper

This helps achieve more natural and consistent results.

Light Area Weight

The Light Area Weight parameter controls how much the size of a bright region affects flare intensity.

Low values treat all highlights more equally
Higher values make larger highlight areas produce brighter flares

This can be used to better match real-world behavior where large light sources tend to dominate flare intensity.

Preview Flare Generation

To visualize where flares will be generated, enable Preview Flare Generation.

In preview mode:

Green markers indicate lights that render ghosts and starburst
Red markers indicate lights that render starburst only

This makes it easier to tune thresholds and limits before rendering the full effect.

Suggested Workflow

Prepare the drive image and adjust brightness, gamma, or blur as needed
Enable Pixel-Driven Flares
Adjust the Pixel Threshold to isolate relevant highlights
Use Preview Flare Generation to verify light placement
Tune Light Brightness Multiplier for correct intensity
Set Threshold To Render Only Starburst for performance
Fine-tune Blur Strength and Area Weight

For high-resolution inputs, downscaling the drive image can significantly improve performance without affecting final quality.

Summary

HDR images can automatically drive flare placement
Bright regions spawn lights ordered by intensity
Preprocessing the drive image improves control
Starburst-only rendering greatly improves performance
Preview mode helps fine-tune generation quickly

Automatic Flare Positioning provides a fast, scalable way to generate complex flare setups while remaining fully art-directable.