The number of direct lighting samples per each GI sample. Increase this value in scenes with visible noise in direct lighting. The default value of 2.0 works well in most cases.
What is it?
The Light Samples Multiplier multiplies the amount of samples specified under "GI vs. AA balance" by a given factor to use them for direct light sampling.
- The total amount of samples is dependent on the Light samples multiplier and GI vs. AA balance values.
- If the Light samples multiplier is set to 1 and the GI vs. AA balance is set to 16, this means that 16 GI samples and 16 direct light samples will be used for each pixel per pass.
- If the Light samples multiplier is set to 2 and the GI vs. AA balance is set to 16, this means that 16 GI samples and 32 direct light samples will be used for each pixel per pass.
- In some situations, it makes sense to reduce one of these values and increase the second one, or even to reduce both. Typically, there is no need to increase GI vs. AA balance above 64 and Light samples multiplier above 4.
- GI vs. AA balance should never be lowered below 2.
The default value of 2 should work well in most cases, but sometimes it should be increased if there is more noise in direct light areas than in GI areas.
See: How can I tell whether noise comes from direct or indirect light?
Light Samples Multiplier works in correlation with GI vs. AA balance.
Where to find it?
You can find the Light Samples Multiplier parameter in:
3ds Max:
Render setup > Performance > Performance Settings.
Cinema 4D:
Render Settings > Corona > Performance Settings > Sampling Balance section:
Examples
Default settings
GI vs. AA balance = 16
LSM = 2
16 passes
Render time: 09:03
16 samples are used for GI and 16 x 2 = 32 samples are used for direct light. These are the default settings of Corona Renderer, which offer a good balance between GI and direct light quality. They will work fine in most interior and exterior scenes.
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Direct lighting pass:
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Global illumination pass:
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Lowered LSM
GI vs. AA balance = 16
LSM = 1
16 passes
Render time: 08:15
The same number of samples (16) is used for both GI and direct light. Note that the quality of GI the GI pass remains the same as when using the default settings, but the quality of the direct lighting pass is lower. Render time is also slightly lower.
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Direct lighting pass:
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Global illumination pass:
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Lowered GI vs. AA balance and LSM
GI vs. AA = 4
LSM = 1
16 passes
Render time: 02:47
The same number of samples (4) is used for GI and for direct light. Note that the overall quality of the image is much worse than with the default settings, even though the number of rendered passes is the same (16). Render time is much lower.
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Direct light pass:
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Global illumination pass:
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Increased GI vs. AA balance, lowered LSM
GI vs. AA balance = 64
LSM = 0,25
16 passes
Render time: 24:25
64 samples are used for GI and 64 x 0,25 = 16 samples are used for direct light. When compared to the default settings example, it can be seen that the GI pass has a higher quality (at the cost of render time), and the direct lighting pass has lower quality.
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Direct light pass:
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GI pass:
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Increased LSM
GI vs. AA = 16
LSM = 4
The default value of 16 samples is used for GI and 16 x 4 = 64 samples are used for direct light. After comparing, it can be seen that the direct lighting pass has higher quality than the indirect lighting pass.
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Direct light pass:
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GI pass:
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