The Glow effect is a part of the post effects 'Default Effects' configuration. It processes the image using two glow specific properties:

  • Glow Size
  • Glow Color
Glow effect

These can be defined just like any other material property such as color.

The glow effect examines the current scene and detects any use of the above mentioned channels. If they are not used, the effect is not executed. Therefore, you don't have to remove glow from the post processing configuration for speed reasons. You only have to remove it from the current post image in case the scene contains glow materials but you still want to disable glow rendering.

Saturation adjustment defines how quickly maximal glow brightness is reached in volume with respect to the distance. If the saturation value is zero, the glow looks brighter around the edges of the object - and has less intensity on the object itself, resulting in a kind of 'aura'. If the saturation is set to 1, an equally bright glow is generated in front of the glowing object as well as the edges.

Full saturation level on the left and zero saturation on the right

The Accuracy setting is an anti-aliasing type quality adjustment. The default value of 0.5 is suitable in most cases. The value range is from zero (fast, inaccurate) to 1.0 (slower but accurate).

The Maximal Size value defines a global limit for channel defined glow sizes. The global control can be used as an easy top level control for the effect, and to speed up the effect. Glow effect must usually render some additional image area outside the visible image to ensure effect continuity at image borders. The global size control instructs the program of what is the required extension area. The smaller the value, the quicker the rendering becomes. The default value is 0.1 (= 10 % of the image width).

Quick Mode uses a simpler solution to generate the glow from interior pixels of a glowing object. If the option is not set, every glow pixel generates a spherical 3D volume of a glowing matter around it, and such glows are blended into the final result. This is a very computation intensive task and takes long time to render. Quick mode uses a simpler approach, but usually the results are very similar - especially when glow size and color values variation is small.

[Note] Note

Suitable glow size values are typically quite small, for example 0.01 (1 centimeter) is pretty good for default scale models. Large glow sizes like 1.0 may take a long time to render.

When rendering an image with post effects to an animation, the rendering engine must expand the image internally. This increases rendering time significantly. If you only need to render one single still image of a scene containing many glowing objects, you can often increase rendering speed dramatically by switching 'Post Proc./Safety Area' and 'Distrib/Box Rendering' off from the render settings property window. Alternatively, you may apply glow as a full image effect, not a box specific effect.