In addition to the below content, see also: Corona Light Material at Chaos Documentation Portal
The Corona Light Material's main purpose is illuminating the scene, but it can also be used in other scenarios. Objects with Corona Light Material applied, from the renderer’s point of view, do not differ from Corona Light objects - they are sampled the same way, and have virtually the same properties.
The typical use for the Corona Light Material is illuminating the scene with light-emitting objects which have different shapes than the ones available in the Corona Light object (e.g. light bulbs, custom-shaped lights, curved LED strips).
Creating Corona Light Material:
In Slate Material Editor -> RightClick -> Materials -> Corona -> CoronaLightMtl
In Material Map Browser -> Material -> Corona -> CoronaLightMtl
Corona Light Material Parameters
CoronaLightMtl Parameters
Corona Light Material:
Emission Color/ Texmap - In the color slot, we can assign a constant color to the Corona Light Material. When a map is assigned in the map slot, it will define the texture which is projected by the Corona Light Material. This can be enabled or disabled by the checkbox next to the map slot.
Intensity - This option controls the intensity of light. The intensity will be the assigned constant color or the texture map multiplied by the entered intensity value.
Opacity - When a texture map is assigned in the map slot, it will define the opacity of the Corona Light Material on the mesh. This can be enabled or disabled by the checkbox next to the map slot.
Emit light - When the Light Emission is On, then this light is a proper emitter, casting illumination into the scene. It can be disabled to create a camera back-plate that does not alter the scene lighting.
Light Emission:
Emit on both sides - When checked, the light also emits on the backside, when disabled, it is back on the backside.
Directionality - How concentrated the light emission should be around the normal. Higher values create a spotlight effect.
Occlude other lights - When enabled, the object using this light material casts shadows from other light sources. (it blocks shadow rays)
Excluding Objects:
Objects Excluded
Exclude/ Include: This option lets us include or exclude objects from the influence of the Corona Light Material (the excluded objects will not receive light from this Light Material).
Shadowcatcher illuminator - Used in combination with the Shadow Catcher Material. If enabled, this light illuminates the shadow catcher instead of casting shadows on it. Enable for CG lights that are being added to the footage and are not present in the 2D backplate/footage.
Visibility
Visible directly - When checked, makes the mesh with the Corona Light Material directly visible to the camera at the time of rendering with color and intensity. When unchecked, the mesh will be invisible.
Visible to alpha channel - When enabled, then the light will be displayed as opaque (white) in the alpha channel.
Visible in reflections - When the option is enabled, then the light reflects on the reflective objects. This can be used to disable reflections of a specific light source in other objects.
Visible in masking elements - When disabled, the material will not be visible in any masking render element (ID, mask, source color,...). It will still be visible in the beauty and CESSENTIAL render elements.
Visible in refractions - When this option is enabled, then the light refracts in other scene objects. This can be used to disable the refraction of a specific light source in other objects.
Generates Caustics - When checked, the CoronaLightMtl will contribute to generating caustics with reflections and refractions in the scene using the fast caustics solver.
Viewport Display
Show wireframe in the viewport: When checked, the mesh with the CoronaLightMtl will be displayed in wireframe mode in the viewport.
G-Buffer ID override
G-Buffer ID override (-1 = off): If set to anything other than -1, this value overrides the 3ds max gbuffer property. This allows you to set values outside of the 0-15 range permitted in the 3ds Max property.
Examples
Example 1: In this example, the Corona Light Material is applied to the mesh behind the mirror, the ceiling spotlights, and the strip light in the top-right corner of the room.
Corona Light materials have the emit light option enabled
Material Setup:
In the following render, the Corona lights have the "Emit Light" Option disabled but the light is currently visible directly and in the reflections:
Corona Light materials have the emit light option disabled
Note: the light visible in the above image comes only from reflections (the lights are visible when reflected in other materials).
Material Setup 1:
Example 2: The Corona Light Material is used in the table lamp with variations in directionality:
Corona Light Material Directionality: 0.0
Corona Light Material Directionality: 0.5
Corona Light Material Directionality: 0.8
Corona Light Material Directionality: 1.0
Material Setup:
Corona Light Material Directionality option
Note: Higher directionality value in the Corona Light can impact performance and introduce some unwanted noise.
Notes:
- The Corona Light Material is the same as the Corona Light Object from the render engine point of view (it is sampled the same way, renders with the same performance).
- The objects with Corona Light Material are considered when setting up and using LightMix.
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Corona light Mtl can be used as a decal.
Example:
In this example, Graffiti textures are plugged into Corona light material which is being projected by the Corona decal.
Corona Light Material used as a Corona Decal
Scene Setup -
Comparing self-illumination with light-emission:
Corona PhysicalMtl with self-illumination:
Render Time: 05:20
Passed Rendered: 29
Material Setup:CoronaLightMtl with Emit Light option enabled:
Render time: 05:20
Passes Rendered: 17
Material Setup:
For more information, see: Should I use Corona Light material or Self Illumination to illuminate my scene?
Note: When comparing Corona Physical MTL with self-illumination and Corona light MTL with emit light option enabled by rendering them for the same number of passes we can see that Corona Physical mtl with self-illumination has rendered faster but Corona Physical MTL with self-illumination has little more visible noise than Corona light MTL with emit light option.
- Objects using the Corona Light Mtl cannot be instanced. This means that if there is a lot of objects using the Corona Light Mtl, and especially if they are hi-poly, this will strongly affect RAM usage and rendering performance. The solution is to use the Corona Physical Material with self-illumination instead, because it can be instanced (but please consider the limitaions of self-illumination explained above).
Example1:
In this example, Corona Light material is used with Emit Light option enabled to illuminate the LED lights in the Christmas tree:
Render time: 11:43
Ram: 6.5 GB
Material Setup:
Example 2:
In this example, Corona Physical Mtl is used with Self-illumination enabled to light the LED lights of the Christmas tree:
Render time: 07:03
Ram: 1.7 GB
Material Setup: