Render settings explained - Corona Renderer for C4D


As opposed to most other renderers, in Corona, there is usually no need to change any render settings. In most scenes, the defaults will work great, guaranteeing the best quality and rendering speed possible. If you would like to understand what each render setting does, you will find short descriptions of each one of them below.


To access Corona render settings go to Render > Edit Render Settings..., or press Ctrl+B, then make sure that Corona is selected as your active renderer.


Note: once any setting is changed, it can be reverted to the safe default value by right-clicking on its spinner. 




Render Settings > Corona > General settings



Progressive rendering limits

By default, rendering in Corona is indefinite - it never stops unless the "cancel" or "stop" button is pressed. You can use these limits to automatically stop rendering after a given time, pass amount, or noise threshold.

See: How to limit rendering?



Global illumination

Here you can change the primary and secondary GI solvers. A rule of thumb is:

  • For interiors - use "Full (multiple bounces)" as the GI mode and UHD Cache as the GI solver.
  • For exteriors - use "Full (multiple bounces)" as the GI mode and Path tracing as the GI solver. 
Available GI Modes:
  • None (direct only) - This mode will disable GI calculation.
  • Single bounce - Using this option will only calculate the first light bounce and no furthermore (GI is also disabled when using this mode).
  • Full (multiple bounces) - This mode will calculate the direct lighting + the GI using any of the available GI solvers.

Available GI Solver options:
  • Path tracing - Path tracing is a rendering algorithm that computes the final image by tracing independent light paths from the camera. It is useful mainly in exterior scenes, where UHD Cache would require longer precomputation times and wouldn't be able to improve rendering speed.
  • UHD Cache - It is a slightly biased, cached solution, which speeds up rendering - should be used (but doesn't have to) as the secondary GI solver in scenes where GI is dominant (e.g., interiors, scenes with many light bounces).

See also: How to use UHD Cache?



Render overrides

Render hidden lights - toggles rendering of hidden lights. Useful when rendering isolated objects.


Render only masks (disable shading) - this enables rendering for mask passes only and skips rendering of beauty-dependent passes. Useful for quickly rendering masks without the need to spend time on other passes.


Mtl. override - this enables the override material, which will be applied to all scene objects. Useful for creating "clay renders" - usually for debugging problematic scenes.



Render selected

This option will allow you to include or exclude a selected object from the rendering process without the need to hide all unwanted objects in the Object Manager. 

Features list:

  • Disable - No change in rendering.
  • Include - Objects added in the Include field will be rendered.
  • Exclude - Objects added to the Exclude field will not be rendered.
  • Viewport Selection - Actively selected objects will only be rendered. 



Denoising

Denoising controls.

See: How to use denoising?




Render Settings > Corona > Camera/Postprocessing



Tone mapping

Here you can enable the simple (EV-based) exposure controls.



Basic photographic settings

Here you can enable the photographic exposure controls (ISO, shutter speed, f-stop). The "sensor width" value also affects the depth of field effect.



LUT

Allows for applying a specific LUT to the rendered image.



Bloom and glare

This controls bloom and glare appearance in the rendered image.

Bloom is a soft, bigger glow around bright objects. Glare is a smaller, sharp, flash effect.

Note: Starting from Corona render v6, you can edit the lens aperture to create different effects. If you were using Corona v5 or older and want to use these new features, disable the "Use legacy (v5) effect" checkbox.

See also: How to use Bloom and Glare?



Sharpening

Sharpen and blur controls.

Sharpen and blur can be used together to get rid of the "pixel-perfect" noise. The default values work well. 



Depth of field

This allows for toggling and controlling the depth of field effect to control the aperture shape.

Depth of field is also dependent on camera settings such as F-stop, sensor size, and target position. By modifying these camera values, different results can be obtained.

See also: How to enable and control DOF in Corona for C4D?



Motion blur

This allows toggling and controlling the motion blur effect.

Motion blur is also dependent on the camera shutter speed. 

See also: How to enable and control motion blur?





Render Settings > Corona > Scene environment



Scene environment

Here you can set a custom scene environment - it will override any currently used native C4D environment. It is recommended to use 8-bit images (JPG, PNG, etc.) to avoid fireflies. 



Environment overrides

Direct visibility, reflections, and refraction override - used to enable custom environment maps. It is recommended to use 8-bit images (JPG, PNG, etc.) to avoid fireflies.



Volume

This controls the material used as global volume (volumetric fog).





Render Settings > Corona > Performance settings



Basic configuration
Lock sampling pattern - locks the "noise pattern" for each rendered frame. Sometimes it is necessary to disable this setting - for example when denoising animations in 3rd party post-processing software. Leave this enabled when using Corona's denoising.

The "Conserve memory (slower)" option can be used to slightly reduce RAM usage and slow down rendering by about 5%. Turning on this option is recommended if your workstation doesn't have enough installed RAM.

The "Adaptive light solver" algorithm can speed up your renders by up to 6 times by learning which scene lights are important at a particular location. Those lights then receive more rays than the others, resulting in a lower noise level.




Sampling balance

GI and light sampling settings. It should not be changed unless it is absolutely necessary and provided that the user is fully aware of what he is doing.


GI/AA balance - the number of AA samples used per pass.


Light samples multiplier - the number of samples used for direct light.


If GI/AA balance is set to 16, and LSM is set to 2, it means that per one pass, 16 samples will be used for the GI, and 32 samples will be used for direct lighting (2 x 16).  



Speed/Accuracy balance

Max sample intensity - lower values will reduce noise but also make the image less realistic and darker. Higher values will introduce noise and make the image slightly more realistic. Value of 0 means that this setting is disabled and the rendering is unbiased. The default value of 20 should always be used.


Max ray depth - controls the maximum amount of reflections and refractions rendered. Increasing or decreasing this value has almost no effect on the rendering speed or quality, so it is strongly advised to use the default value of 25. 



Displacement

Displacement settings. In most cases, "screen size" should be enabled. The default value of 2px should work well.

In case of visible flickering or other problems, "world size" can be enabled. The world size value is dependent on scene scale and other factors - this is the smallest allowed detail size in the scene displacement. Too high displacement settings may result in excessive RAM usage.



Interactive rendering

Max passes - controls how many passes may be rendered with IR.

The "Force path tracing" option can be used to force the IR to use path tracing as the GI solver.

When the "Enable motion blur" checkbox is turned on, the motion blur will be shown in the IR.

The "Fast preview denoise during render" option, as it says, will turn on the denoiser to obtain fast preview denoised images when using the IR.





Render Settings > Corona > Development / Experimental stuff

These settings are only available if "Enable devel/debug mode" is checked under Corona > Preferences.

This is used only for debugging and testing unfinished features of Corona Renderer. This should never be changed unless the user is explicitly asked to do so. Changing the values here may result in incorrect and extremely slow rendering times or cause other unexpected problems.




Render Settings > Corona > Frame buffer settings



Frame buffer

Clear VFB in between renders - whether or not the VFB should be cleared between each next rendering. 


Render stamp - toggles the render stamp. It is baked into the saved image. The stamp contains useful information such as Corona version number, render time, and other statistics. The render stamp can be enabled or disabled interactively during and after rendering. 

See also: Renderstamp variables.



Image filter

Image filtering settings. These should not be changed unless it is absolutely necessary.





Render Settings > Corona > Secondary GI: UHD Cache



For a more detailed guide, see: how to use UHD Cache? 


Preset - "Still frame" preset should be used for stills. "Animation" preset should be used for animations to prevent flickering or other possible issues.


Precision - lower values mean faster precomputation and more bias. Higher values mean slower precomputation and more realism. The default value works well and should not be changed.


Show previsualization - toggles the pre-rendering visualization of the UHD Cache calculations.



Save/Load

Precomputation:

  • Calculate from scratch - calculates a new cache each time rendering starts - the default setting, useful for still images.
  • Load from file - loads a specified cache file and uses it for rendering - useful for rendering animations without moving objects or lights. 
  • Load from file + append - loads a specified cache file and uses it for rendering; new information will be calculated for the cache and stored in it if needed - useful for animations with a subtle object or light movement.


After render:

Discard - discards any computed cache after the rendering is finished.

Save - saves the computed cache to a specified file. 


Filename - specifies where the UHD Cache file should be saved or where it should be loaded from.



Render Settings > Corona > Team render

Team render settings.



Configuration - Allows selecting the Team Render's functionality, whether if it will be Automatic or Manual.

Client update interval [s] - This value will set the time interval in seconds to communicate with Team Render clients across the network.

Maximum size of packets [MB] - The value will define each information packet's maximum size that will be sent to the Team Render clients across the network.

See also: How to use Team Render (Distributed Rendering)?