This depends on the kind of lighting you want to use. Generally:
- Corona Light material technically does not differ from Corona lights, and just like them, it should be used for objects that will be the main sources of strong light in your scene. That is, for example, lamps, cove lights, candles - light sources that cast shadows and illuminate other objects.
- Self-illumination in Corona Physical Material or Corona Legacy Material should be used for objects that glow in the dark but do not really illuminate your scene. For example lava, glowing buttons, fireflies. Light emitted by self-illumination will be clamped by MSI.
Misuse of Light material and Self-illumination may lead to excessive noise or very high render times because these two kinds of materials are sampled differently. For the Light material, Corona sends special rays to sample it like light. Self-illuminated objects are sampled like any other object.
Below is a simple guide on material usage:
| Usage / light type | Corona Light Mtl or Corona Light object | Corona Mtl with Self Illumination |
|
Using as the key light source (casting shadows, illuminating other objects) |
GOOD |
BAD - slow, noisy |
|
Subtle light source (not illuminating other objects) |
NOT RECOMMENDED | GOOD |
|
Dim light on a very big area (one big slightly glowing object or lots of slightly glowing objects) |
BAD - slow | GOOD - if the light is dim |
Examples
1. Key light source
Light Material
15 passes
Corona Material with self-illumination
15 passes
2. Key light and faint light sources
A
Tree lights - self-illumination
Table lamp - Corona Light material
46 passes
Rendering time: 00:07:01
Rays/s: 3,862,596
Correct setup.
B
Tree lights - Corona Light material
Table lamp - Corona Light material
46 passes
Rendering time: 00:14:38
Rays/s: 1,183,937
Incorrect setup. Samples required by the Table lamp are "stolen" by light material assigned to the lights on the tree. Rendering is slower and its quality is worse.
C
Tree lights - self-illumination
Table lamps - self-illumination
46 passes
Rendering time: 00:14:32
Rays/s: 1,905,835
MSI=20 (default setting)
D
Tree lights - self-illumination
Table lamp - self-illumination
46 passes
Rendering time: 00:14:30
Rays/s: 1,914,490
MSI=0 (unbiased mode)