These settings provide control over some advanced settings of the renderer.

Lock Sampling Pattern

Locks the AA_seed so that the sampling noise won't change with the frame number (avoiding the film grain look).

Use Autobump in SSS

If enabled, autobump is visible in SSS. Enabling this option will take into account the effect that displacement_autobump has on the ray-traced BSSRDF's result. This helps capture the high-frequency details of the surface more accurately when using autobump.

Beware that enabling this option will triple shader evaluations with SSS, resulting in much longer render times.

Indirect Specular Blur

Sets indirect specular blurring to reduce caustic noise. Setting to zero gives the most accurate but also noisy renders, while higher values blur caustics to reduce noise.

Nested Dielectrics

Enables the "nested dielectrics" system for IOR tracking in scenes with adjacent dielectrics. Defaults to on.

Low Light Threshold

Raising this value can speed up rendering by allowing Arnold to ignore tracing a shadow ray for light samples whose light contribution is below a certain value. The point of low_light_threshold is to save casting shadow rays when Arnold knows that the error from not casting that ray is below a certain amount. This makes sense because below a certain threshold there will be no perceptible difference between shadowed and unshadowed areas.

Roughly, what is taken into account to discard a shadow ray is its maximum possible incoming irradiance, which is linearly related to the light's intensity and decreases with distance. The specific number will vary depending on your exposure and light intensity values, but the default value is reasonable for the default exposure/light intensity values. This will typically help more in scenes with lots of lights with a finite area of influence, like a cityscape for example. It will help much less with a single strong source of light.

You should never be able to see the boundary when this optimization kicks in. If you can see it, you need to make the threshold lower. The aim is to prune shadow rays that don't contribute to the final image


In the example below, increasing the low_light_threshold to 0.1 shows a good speedup in render time (in this case, more than twice as fast) with little noticeable difference in the image.

A slightly higher threshold can offer significant rendering speed increases without noticeably darkening the image (rollover image).

 

However, increasing the low_light_threshold value too much can have an adverse effect on the lighting:

The Utility shader's nlights color mode can be used to see how many lights are influencing a shading point when adjusting the low_light_threshold. 

low_light_threshold: 0 to 1. Red = all lights, blue = low values, black = no lights.

Distribute Still Image Over Frames

When enabled the render is split up over the specified number of frames, allowing you to render the slices in parallel. Then you can put the slices together via a script (e.g. in Photoshop).
Columns
Specifies the number of columns of the distribution. The number frames are the columns multiplied by the rows.
Rows
Specifies the number of rows of the distribution. The number frames are the columns multiplied by the rows.
Set frame range
Sets the frame and preview range of the scene according to the specified columns and rows. Also sets the Frame range to All Frames on the Output panel.
Get coordinates
Displays the coordinates of the slices, which can be used in a script to put them together.

Render Selected Objects

This option allows you to re-render the selected objects and merge the result into a previously rendered image. This can be useful when making fine edits on a final render.

Note that only pixels of selected objects are rendered and surrounding objects affected by the look change won't be updated.

Selection
Specifies which objects will be re-rendered.
  • active objects: Objects selected in the scene.
  • active materials: Objects which have the selected materials assigned.
  • active objects & materials: Selected objects and objects which have the selected materials assigned.
  • list: Objects listed on the UI. Use this mode when rendering from the command line.
Select object hierarchy

If enabled, children of the selected objects are also rendered.

Select instances

If enabled, instances of the selected objects are also rendered.

Background

Specifies the image which the updated pixels will be merged into.

  • black: No background.
  • file: Load an image from a file, e.g. previously rendered image. You can load a frame sequence using a padding pattern (e.g. ####) in the file name (e.g. /path/to/my/image_####.exr). You can also specify start, end, step frame, offset and loop mode via the settings under the Background image input field.

Current limitations:

  • Background images can not be loaded directly from the Picture Viewer. Unfortunately the SDK has no methods to read image buffers stored in the PV history. The only option right now is to save to file from the Picture Viewer.
  • The feature works only with the native Save option in the render settings, does not work with Arnold drivers. That means it can not be used with the Arnold denoiser.
  • The feature does not work in single frame Team Render.

AOV Shaders

A list of shaders that will be evaluated after the regular surface shader. With this, it's possible to add shaders to set specific AOVs without modifying the original shader tree. If an atmosphere or background shader is set, these global AOV shaders will also be run for atmosphere and background contexts. It is useful for instance in the cryptomatte workflow.

Operator

The assigned Arnold Operator network is active in the scene.

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