Interactive LightMix lets you adjust the intensity and color of your lights and light-emitting materials during and after render – perfect for anything from subtle adjustments through to turning day into night.
Note: Starting from Corona 12, the new VFB 2.0 is the new default VFB in Corona, featuring an updated interface with improved user experience. For a complete overview, refer to the Corona VFB 2.0 at the Chaos Documentation Portal.
What is interactive LightMix?
Interactive LightMix lets you render an image just once, and then change colors and intensities of the lights directly from the Corona VFB. It can be used after the rendering is finished and, like any other post-processing effect in Corona, during the rendering (be it production or interactive mode). Some of the improvements added over the years include:
- A possibility to bake LightMix parameters into the scene lights and light-emitting materials (the >Scene / Bake button)
- Better automatic creation dialog with different ways to group lights, information on RAM usage, and checkboxes for denoising and considering hidden lights
- A better, more user-friendly user interface
Starting from Corona 12, with the new VFB 2.0, it is possible to create and manage multiple LightMix setups within a single render by manually adding multiple LightMix render elements.
See: Using multiple LightMix elements at the Chaos Documentation Portal
LightMix can be used on Corona EXR (.CXR) files outside of any 3D software using the Corona Image Editor.
Where to find it?
LightMix can be set up either automatically or manually.
To set up LightMix automatically:
Simply click the Open Corona Interactive LightMix Setup button in the Corona Toolbar:
Alternatively, you can go to Render Setup > Scene and under "General Settings" press the "Setup LightMix" button.
Corona Interactive LightMix Setup dialog will then pop up, allowing you to:
- Choose the way lights are grouped - based on instances, groups, layers or individual lights.
- See how much RAM will be used by each LightMix layer (calculated depending on the resolution of the final render)
- Decide whether hidden lights should be also considered by the LightMix setup
- Decide whether denoising should be applied to all LightMix and LightSelect render elements
Instanced lights – Separates LightMix layers by instances. All instances of a single light object end up on a single layer. Any unique light in the scene is stored in its own individual layer.
Grouped lights – Separates LightMix layers by groups. Any group of lights ends up on a single layer. Any light that is not part of a group is stored in its own individual layer.
Layers – Separates LightMix layers by layers.
Individual lights – Every single light ends up on its own individual layer.
Once the settings are confirmed with the "Generate" button:
- One CShading_LightMix element is automatically added to activate the LightMix tab in the Corona VFB.
- One CShading_LightSelect element is added with the environment lighting included - this allows for changing the color and intensity of the scene environment.
- Multiple CShading_LightSelect elements are automatically added - this allows for changing the color and intensity of each scene light.
A list of automatically generated LightMix and LightSelect render elements.
After using this one-click solution, you can simply start rendering the scene (both regular and interactive rendering will work), and then go to LightMix tab in the Corona VFB to change the intensity and color of each light:
After using the automatic setup, LightMix tab in the Corona VFB becomes available.
To set up LightMix manually:
- Go to Render Setup > Render Elements, and then:
- Add at least one CShading_LightMix render element - this is required to activate the LightMix tab in the VFB. Adding more than one LightMix render element lets you have multiple LightMix setups when rendering.
- Add at least one CShading_LightSelect render element - this is required to be able to control a light or environment.
CShading_LightMix and CShading_LightSelect render elements can be added manually.
Each light that you wish to control should be added to the "Included light sources" list in each CShading_LightSelect render element. You can add one or more lights to each LightSelect element. Each LightSelect comes with its own color and intensity in the Corona VFB LightMix tab. Additionally, you can check the "Include Environment Light" checkbox to control environment lighting.
Note: Objects that use the Corona Light Material with Emit light option disabled cannot be added or selected for the CShading_LightSelect element. The same applies to objects with self-illuminated materials.
LightMix and Denosing
You can decide whether denoising should be applied to each LightSelect render element. To denoise the whole LightMix output, you must turn on the denoising option for all LightSelect elements:
As of Corona Renderer 4, the "Rest (unassigned)" LightMix item can be denoised and saved just like any other render element.
This is achieved by allowing any LightSelect render element to act as the "Rest (unassigned)" render element by enabling the appropriate option ("Include lights not assigned to other LightSelect elements") for the LightSelect element:
the LightMix element with lights not included in other LightSelect elements.
This render element will be denoised just like other LightSelect render elements as long as the "Apply denoising also to this render element" option is enabled.
Please note that if any lights are left unassigned to any LightSelect render elements and no LightSelect render element has the "Include lights not assigned to other LightSelect elements" option enabled, these lights will still end up in the Rest (unassigned) section but you will not be able to denoise the render element or save it.
How to use it?
After setting up LightMix (either automatically, or manually), the color and intensity of each light can be changed in the VFB. Simply go to the LightMix tab in the Corona VFB and change the desired parameters - this can be done during or after rendering, for both production and interactive rendering:
After setting up the Interactive LightMix, its dedicated tab in the VFB becomes available.
You can also use additional buttons above the lights list:
| Button | Description |
| Bake currently set LightMix colors/intensities into the scene lights. | |
| Save settings of the current displayed light mix element to a config file. | |
| Load light mix settings from a config file to the currently displayed light mix element. | |
| Enables all entries if some are disabled or disables all if all are currently enabled. | |
| Set all intensities to 1. | |
| Set all colors to white. |
Additional Tips:
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LightMix colors can be copied by dragging and dropping a color swatch onto another swatch.
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LightMix colors can be reset to pure white by right-clicking on a swatch.
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You can also right-click on the light names to select a specific light in the scene, add that light to the current selection, or remove that light from the current selection.
Compositing LightMix layers in other applications
To compose different LightMix layers (LightSelect render elements) so that the final image looks the same as in the Corona VFB open the layers in the application of your choice, and stack them on each other in any order using the "Add" blending operation. In Adobe Photoshop it is called "Linear Dodge (Add)".
Using LightMix with multiple suns and environments
An example image with multiple suns and environments controlled by LightMix.
You can add multiple suns and environment maps to your scene, and then control their appearance with LightMix. This means that you can render just once, and pick between completely different lighting conditions, adjust sun and environment intensity and color, and even have two or more suns illuminate your scene at a time. No re-rendering needed!
See: How to set up multiple suns / environments
Using Multiple LightMix Elements
Starting from Corona 12, with the new VFB 2.0, it is possible to create and manage multiple LightMix setups within a single render by manually adding multiple LightMix render elements.
See: Using multiple LightMix elements at the Chaos Documentation Portal
What are the limitations?
There are some technical limitations when using LightMix:
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Keep in mind that the LightMix color acts as a filter on the original light color
The color in the LightSelect does not replace the original color of the light but instead filters it (for example, if a light has a strong red color in the scene itself and you add green in the LightSelect, the result will be an orange color in the LightMix render). This means that the more saturated the color of the light in the scene, the less control you will have over it in LightMix - this can be resolved for any lights that you plan to control extensively in the LightMix by leaving the light a white color in the scene.
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Using extremely high or low light intensities
This will result in persistent noise (fireflies).
Solution: after setting the LightMix as desired, use the >Scene (Bake) button in the VFB LightMix tab to bake your settings into the scene.
Using extremely high or low light intensities in the LightMix always leads to excessive noise.
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Adding lots of lights and rendering in very high resolution
This can lead to excessive RAM usage. A warning message should appear when attempting to set up LightMix with many lights.
Solution: render your image in low resolution to keep memory usage low, then adjust LightMix settings as needed. Once the LightMix setup is complete, use the >Scene (Bake) button to bake all custom light settings into the scene, then disable all LightMix and LightSelect render elements, and re-render your image in high resolution. This way you will be able to use your LightMix settings in a high-resolution render, without the high RAM usage.
Troubleshooting
1. When I go to the LightMix tab in the Corona VFB, it says that "Interactive light mixing is currently not possible"!
This happens if LightMix has not been set up correctly. Some of the reasons include:
- LightMix not being set up at all
- All 3ds Max Render Elements are disabled
- There is no CShading_LightMix render element on the 3ds Max Render Elements list
- There are no CShading_LightSelect render elements on the 3ds Max Render Elements list
The solution is to make sure that LightMix is properly set up, and that the Render Elements are enabled. The easiest way to make sure LightMix is set up correctly is by using the dedicated button in the Corona Toolbar or the Setup LightMix button in the Scene tab of the Render Setup window.
See also: