The Rendering > Volumetric Light effect

The Volumetric Light effect is in the same category as the Lighting effect but it works in a different way :

In this effect, the light source is located under the current layer and it gives the impression of volume to the light.

Here is an example :

Create a new project et fill the current image with an opaque black color.

Set the background as Color in the Timeline. The background has to be white.

Now put a TVPaint logo in Erase mode on this layer with the TextBrush tool, then change this layer to an Anim layer with about twenty images.

Make the Center setting move along a path from left to right.
You should get an animation similar to the one like the image sequence on the left.

* The Volumetric Light effect requires to adjust the position setting of the light source and possibly its Path, its Power and its Length.
* You can also define the light color, use a color gradient (like in the example on the left) or even have a color that depends on the source image. You can select one of these options in the Color Source menu.

* You can also define one of the various blend modes for this color through the Blend menu.

The substitute mode is only available in this menu, erasing the source image pixels (nearby a white opaque logo on a transparent layer with a black background.)

* The Channel menu gives several others possibilities :
- Invert Alpha : Lighting comes from the image opaque pixels (see below for example).
- Alpha : Lighting comes from image transparent pixels : that's what's happening in the example above.
- Luminosity : The more luminous a pixel is, the more lightrays it will let go.
- Red, Green, Blue : The more red (or green, or blue) component a pixel has, the more lightrays will go through it.

In the source image on the left below, only the sky and the green tree will emit lightrays when the blue channel option is selected. (The green tree color is partially composed of blue.)

Source ImageLuma channel

Invert Alpha channelBlue channel

* The Shimmer section permits to generate interferences in the Volumetric light :
The Size setting is used to manage the distribution of these interferences.
The Angle and Rotation make these interferences pivot and can give the feeling that the lightsource is rotating.
The Variation setting accents the contrast between rays.

Without ShimmerWith Shimmer

The Mask section allows you to limit the lighting in a circle whose radius has to be defined.