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I'm trying to achieve a nice bloom around my lighting with some principled volume fog but I cannot seem to achieve the result I'm looking for (rendering Cycles). Is there something I am doing incorrectly? enter image description here enter image description here

enter image description here

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  • $\begingroup$ OK, I see some glow and I'm guessing the upper image is reference, not your rendering? Please be more specific. $\endgroup$ Commented Jan 18, 2022 at 7:37
  • $\begingroup$ Both images supplied are my renderings $\endgroup$
    – Matthew
    Commented Jan 18, 2022 at 12:39
  • $\begingroup$ Any take on why it's not giving me a nice bloom? $\endgroup$
    – Matthew
    Commented Jan 18, 2022 at 23:54
  • $\begingroup$ I see some bloom, idk what you are going for. $\endgroup$ Commented Jan 19, 2022 at 7:14
  • $\begingroup$ Look how for example this picture achieves some nice light streaks from the street lamp blendernation.com/wp-content/uploads/2020/10/image7-4.jpg $\endgroup$
    – Matthew
    Commented Jan 19, 2022 at 12:40

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First of all, I'd like to mention that volumetric scattering does work with emission shaders, not just lamps. Although if you can use lamps, use them instead as they are easier to compute, therefore shorter render times.

The simple answer is to either increase the volumetric density and/or increase the brightness of your lights.

These are objects with emission shaders set to a low strength.

enter image description here

This is the same scene, but I've replaced the shader on the object on the bottom with another emission shader with a higher strength value.

enter image description here

As you can see, the scattering is much more visible now. Although, because the light is brighter, the ground is lit more brightly. This is physically accurate, but may not be what you want.

If you want the scattering with low volumetric density and dim lights, here comes the slightly more complex answer which includes view layers.


Duplicate all lights and objects that you want to have control over its scattering and move them into a new collection. Replace the new objects with a new emission shader with a higher emission strength, or in the case of lamps, just increase their power. In my case, I'm only going to affect the light at the bottom.

enter image description here

Now add a new view layer with the button on the top right. In my case, I've called this new layer "Fog Pass". Whilst still viewing the new view layer, enable the Volume Direct option under View Layer Properties > Passes > Light.

enter image description here

Go back to the main view layer and disable the collection with the stronger lights in.

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Render one frame with F12 and head into the compositor. By default, you will have a compositing workspace as the top, displayed as tabs. Check the Used Nodes button. Add a view node with Add > Output > Viewer. Check Backdrop under View > Backdrop on the right. Anything you plug into the view node, you will see in the background.

You should have a Render Layers node connected to a Composite Node. Duplicate the Render Layers Node and set the View Layer to "Fog pass".

enter image description here

The VolumeDir output on the "Fog Pass" render layer contains the light scatter and only the light scatter. Mine looks like this :

enter image description here

Add denoising nodes in places if necessary. Add a Colour Mix node and set to Add. Using the Fac slider, you can add the fake lighting on top of the normally rendered layer without adding any extra light. Emphasis on fake, as this is not physically accurate.

enter image description here

Remember to connect your nodes back to the Composite node from the Viewer node. Otherwise, your render will be black.


Image comparison:

enter image description here

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  • $\begingroup$ Appreciate your response, will take a crack at this tomorrow and post results. $\endgroup$
    – Matthew
    Commented Jan 21, 2022 at 3:12

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