# Emission: Red glow while the object itself is white

I want to make something like this in Blender:

So I created a Torus and I created two emission materials for it (one for the right side and one for the left side) with two different colors and increased their strengths. And then I added a Fog Glow filter (Glare) and a Volume Scatter to the World. But this is the result:

I want the material to be white and a nice green (for the left side) and purple (for the right side) glow around it (like the reference photo). How to achieve this effect? (Blender v2.82 and Cycles)

• In this image I suspect the object is not white - it's actually bright pink and bright blue, but it's so bright that even the relatively low-intensity G and B channels (R and G for the blue side) "saturate", making it look white. Not sure how Blender handles this effect. Mar 5 '20 at 13:11

From a physically based rendering point of view, the problem you are running into is that Blender's HDR tone mapping is trying too hard to be helpful.

The effect you see in the reference image occurs due to blown highlights from a high dynamic range image being clamped to a low dynamic range. For example, the color (300, 1000, 300) might be clamped to (255, 255, 255), turning an unrepresentably-bright mostly-green color into solid white.

In Blender 2.8+, the default color management settings use Filmic tone mapping, which attempts to map HDR colors down to LDR colors in a way that preserves some sense of hue and saturation rather than just clipping out-of-range color channels to 255. This makes high-luminosity green still show up as mostly green in the final render rather than being clamped to white, unless you turn the intensity up really high.

There are a few ways of working around this to get the intentionally-blown-out effect you are looking for:

1. (not recommended) Disable the Filmic lookup table (LUT). You can do this by going to the Render Properties tab and, in the Color Management section, changing the View Transform from Filmic to Standard. However, this has a number of undesirable side effects. One such side effect is that there will be a lot of stairstepped pixels around the blown-out areas due to the unintelligent color clipping.

2. Change to a higher-contrast Filmic LUT. The setting for this is the Look drop-down, right under the aforementioned View Transform drop-down. Try switching from the default Medium Contrast to one of the higher-contrast Looks.

3. Turn the brightness of your emission material way, way up. It is easy to underestimate the dynamic range of light sources that exist in the real world. The sun is thousands of times brighter than typical indoor light. To compensate for this, you will probably also have to turn the density of your volume scattering way, way down.

This sample render uses a combination of methods 2 and 3. The file simply contains of a ring with colored Emission materials set to a Strength of 100, together with a world Volume Scatter with a teeny-tiny density of 0.015. The Look has been changed from Medium Contrast to High Contrast. I also set up AI denoising in the compositor to bring the render time down to a reasonable level on my laptop.

As you can verify with an image editor, the color of the ring itself appears to be (255, 255, 255), but this is only due to the tone mapping being performed; in HDR linear color space, these values are much higher and more saturated, and this is indirectly visible through the scattered light around the ring and in the reflections on the floor.

If you really want to use Cycles: Add a box which encloses the entire scene, add a principled volume shader to the box and play with Density and Anisotropy:

In comp you can add a Denoise node to save render time and a Glare node to introduce a soft glow:

If the volume takes forever to render, a few blur nodes with various blur amounts can introduce a 'colorful blur' in comp as well:

• I'm currently using nodes and yes, it gives nice results, but the goal is to make the object itself white and make the pixels around it glow its color.
– Bean
Mar 3 '20 at 7:39
• Had some time while waiting for another render, hope you don't mind the edit :) was fun playing with your eevee file @ManuJärvinen
– p2or
Mar 3 '20 at 10:56
• Nice one @p2or ! Gotta check your modifications once I’m back with the machine :) I had hard time to make the glow happen straight out of the render Mar 3 '20 at 11:00
• The "trick" is to raise up the strength of the emission to a foolish value like 1000+, another rendering using a value of 2500. I think that's the reason why the ground looks so bright in the reference. Cheers! @ManuJärvinen
– p2or
Mar 3 '20 at 12:28
• Cool! I guess Cycles is ok for this too - just gotta leave it render overnight Mar 3 '20 at 12:30

That's actually quite challenging. I wonder if the maker of your reference image used some compositing.

At least I think separate lights were used for the background objects.

And to answer your question, Eevee's Bloom makes a nice colored glow :)

Here's my try:

• I'm using Cycles (as I mentioned in the question). So I can't use the Bloom effect :(
– Bean
Mar 3 '20 at 6:58
• Oh man, I missed that one. Hmm Mar 3 '20 at 6:59
• Can I ask what's your reason for using Cycles for this kind of task? Volumetrics sure are not the fastest stuff you can render with Cycles... Mar 3 '20 at 7:19
• I want it to be photorealistic. Actually I don't like using EEVEE and I almost never use it.
– Bean
Mar 3 '20 at 7:20
• Okay, yeah, makes sense. But I like how fast Eevee is :) To each their own... Mar 3 '20 at 7:22

You could try using a fresnel node like Ian Hubert does in this video https://youtu.be/8eNN2Ep3Rqs Make one of the emission shaders white and the other your desired color, use a color ramp to control the amount of fresnel. If that doesn't work, crank up the emission strengths.