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My light only blooms in the mirror. Is this normal?

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Message 1 of 24
jnvfxartist
869 Views, 23 Replies

My light only blooms in the mirror. Is this normal?

Hello Arnold Answers.

I was doing a quick scene render test and for the first time I added mirrors, I noticed the light sources are only glowing there and not in the main scene itself.

4707-october4th2019-540p-3hour46mins-3cam-8dif-6spec-4t.jpg

For this scene, I'm only using two lights: one Arnold disc light and one mesh light. I've also have an emissive material applied with the indirect diffuse set to 0.

I once turned off the emission material and toggled "light shape visible" but the bloom still only shows up in the mirror.

Regarding the mirror material, I'm actually using the physically correct version by placing a glass object in front of a really shiny metal base.

Edit: Here is the the actual scene information. Again, I did turn off the emission material and turned on "light shape visible" but the bloom only shows up in the mirror.

4708-lightbulbsglitch.png

23 REPLIES 23
Message 2 of 24
madsd
in reply to: jnvfxartist

If you want the lamps to glow, you kinda need to add a post bloom/glare effect.

There is a free framebuffer for 3ds max you can download and give a try.
http://www.monotoneminimal.com/vfb

Message 3 of 24
jnvfxartist
in reply to: jnvfxartist

I downloaded the tool and played around with it, but I find the bloom effect to be less natural compared to the one in the mirror. I also have to edit them out since VFB applies bloom to the entire image which results in the reflections being multiplied.

I do like the tool for playing with the exposure and control over the shadows however.

Message 4 of 24
madsd
in reply to: jnvfxartist

The mirror creates bloom due to the rays travel through some medium, you can sharpen them up so the reflections does not bloom, this will return a situation where you can bloom everything.

You cannot get any bloom on the direct rays when you have no medium infront of the rays so they scatter, you either do it in post, or add a coat on the lens with blury refractions to create it, which is not very sexy.

Message 5 of 24
lee_griggs
in reply to: jnvfxartist

I would use a disk light and add a small amount of Atmosphere Volume. You could use Affect Reflection to control how much you want to see in the mirror.

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 6 of 24
madsd
in reply to: lee_griggs

Yes this would work well as well.

Message 7 of 24
jnvfxartist
in reply to: lee_griggs

Oh, I like this idea. And since it's a bathroom, I can even justify it by saying someone just had a shower, hehe. I'll try it out and post back the results.

Message 8 of 24
jnvfxartist
in reply to: jnvfxartist

@Lee Griggs method worked. I added the atmospheric volume and turned down density to the lowest single digit (otherwise, the entire scene was just white) but otherwise, the bloom looks much more natural now compared to postprocess methods.

4726-itworked.png

I'll maybe tweak some other settings so the god rays aren't so long. Maybe the Attenuation or the Eccentricity parameter does this?

Message 9 of 24
jnvfxartist
in reply to: jnvfxartist

Here's one more update. I now have settings that will work under any interior lighting so it doesn't have to resemble foggy weather or look cartoonish.

4736-october7th2019-360p-18mins-3camdifspectrans-correc.jpg

4737-volume.png

I'll explain what I did:

Density: The lowest value in the material only allowed for 0.01. While not too unacceptable, I wanted an even lower value so I could use this in any interior scene without problems. So I plugged in a vector/texture map and was able to use an even lower value (0.001).

Attenuation: I played around with this however, I decided to leave it at the default of 0. What I found was increasing this number stopped the light rays half way, leaving the floor and surrounding areas too dark or without any illumination.

Eccentricity: I increased this to 0.9. My rationale, I wanted to exaggerate the bloom effect and create a nice glow around my lights. By leaving it at 0, it resembled "god rays" or the bloom effect traveled down when I want it to go up and disperse in a circle like real lens flare.

Samples: Left it at 5. When doing a final production render, everything gets more crisp anyway.

Of course, these are just my settings I used and some of them have a stylistic purpose given them.

Also, ignore the noise. It's not coming from the bloom/fog volume, I just have a really old CPU.

Message 10 of 24
lee_griggs
in reply to: jnvfxartist

Nice, you can also reduce the effect on a per-light basis using volume contribution.

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 11 of 24
jnvfxartist
in reply to: jnvfxartist

@Lee Griggs

Thanks. I just used that technique to control the bloom on one of my lights without having to affect all of them.

4748-volume2.png

I've also made a few more updates.

Samples: In an earlier post, I said to use 5 in the atmospheric fog volume. However, after closer inspection I raised it to 10. This was to help clean up some harsh artifacting and noise.

EXR format over JPEG: This one should be obvious but an EXR format is absolutely critical for bloom, since there is a wider bit depth. Going with JPEG limits this potential since there is more banding and compression instead of a nice soft gradient. The image I posted above, the left is a JPEG source and the right (final render) came from an EXR.

I've also said this was originally meant for an interior scene, but since there are now so many ways to control the strength of bloom in the Arnold settings, I think the atmospheric volume could be used in any scenario.

For example, I was just outside and having lens flare would be important for all the car and street lights you see at night.

4749-bloom.jpg

Message 12 of 24
lee_griggs
in reply to: jnvfxartist

Yes, definitely. Atmosphere volume is great fun to play around with. If you get the time, could you possibly upload a final image with sample settings used? Btw, have you tried using the Arnold denoiser with this interior?

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 13 of 24
jnvfxartist
in reply to: lee_griggs

I'm doing a re-render of a previous scene for my portfolio, so I'll definitely have a higher res version of this ready soon.

As for the denoiser, yes. The picture posted above with the before and after comparison, the after is from a denoised source that I saved out as an EXR format. It's just that I posted it at 240p to get it out faster, but a HD image with textures will be ready by the end of the week. I'll let you know when it's finished.

Message 14 of 24
jnvfxartist
in reply to: jnvfxartist

Apologies for the long wait @Lee Griggs I'm actually in the process of upgrading my PC, so some things still aren't final.

However, I do now have some HD images of the bloom in effect, and I'm actually going to do a 4 part series where I'll continue to toy with these settings under different environments that I'll be posting to my portfolio.

https://www.artstation.com/artwork/zAqRN6

Here's the first two.

4788-calgarykitchen-13-improved-bloom.jpg

4789-calgarykitchen-41.jpg

Depending on how fast my new CPU is, I might even try to go from 720p to full 1080p HD.

Edit: Increased the exposure. I originally wanted to do a cinematic/4K blu-ray thing but I guess for this type of art (Archviz) that is not the best idea.

Message 15 of 24
lee_griggs
in reply to: jnvfxartist

Nice. What samples did you use? Have you tried clamping for the fireflies?

Is it supposed to be that dark? Are you rendering to 32-bit EXR so that you can adjust the gamma/exposure in post?

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 16 of 24
jnvfxartist
in reply to: jnvfxartist

@Lee Griggs

I made backups of all the 32-bit EXR so I can definitely adjust the exposure. I was inspired by images I saw of 4K Blu-rays (in particular, Batman heh) so I was trying to mimic that level of exposure, but I think in the future I'm going to raise the brightness, especially since this is suppose to be Archviz and not Cinema.

But here's the settings and increased exposure.

4777-settings2.png

The CPU I'm using is ancient, so I'm still planning on re-rendering tomorrow as soon as I swap out my i7 860 for a Ryzen 2600x. In the past, I did actually have some clean renders but since my scenes have gotten more complex, I just figured a 10 year old CPU just can't keep up anymore.

4774-september13th2019-480p-3hours-6cam-3difspectrans-d.jpg

This was one of my earlier WIP scenes and it even had depth of field, but as the requirements got bigger, my computer started to struggle with rendering that would take days.

Message 17 of 24
lee_griggs
in reply to: jnvfxartist

Looking good. Some of the sample settings look quite high though:

  1. Does the room look much different with just 3 or 4 Diffuse Ray Depth (should reduce render time)?
  2. Why is Specular and Specular Ray Depth so high?
  3. I would increase Camera (AA) to 5 and see if you can reduce Specular etc.
  4. You should only need to increase Transmission if you have a lot of rough refractive glass in the scene. If not I would lower it the default 2.
  5. Again 6 SSS will add a lot to the render times. What is in the scene needs SSS? Bowls?

There are some tips here for reducing noise in a scene.

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 18 of 24
jnvfxartist
in reply to: lee_griggs

1. I did experiments with 3,6 and 8 ray depth and found that the difference in render time wasn't actually much. Increasing the actual samples of the diffuse,spec,trans had a bigger impact.

2. Too low spec samples was causing noise on leathery surfaces as well as metals like the refrigerator. Originally, 3 spec samples was the sweet spot but I bumped it up for the final render just to be sure.

4787-oldtest.png

3. When I was using depth of field, 6 Cam AA was the target, but I still needed more samples to clean up metals and leather surfaces. With DOF disabled, I found I could lower it to 3 Cam.

Message 19 of 24
jnvfxartist
in reply to: lee_griggs

Part 2:

4. Do you mean ray depth? I actually have a lot of hidden transparent surfaces with a water cooler and the TV screen being tucked in the corner.

4786-oldtest3.png

5. SSS is for the indoor plants ( Palm leaf, Ginger and Aloe Vera). I originally intended to have an outside garden but I decided to save it for future scenes and use the house plants as a test run.

From earlier tests, I found that 12+ samples was needed for a clean surface, but I reduced it to 6 SSS which helped cut render time in half.

4785-oldtest2.png

When I rendered the scene again using daytime lighting vs incandescent, 6 SSS is too low vs 8 samples.

Message 20 of 24
jnvfxartist
in reply to: jnvfxartist

Bumping this again, because I finally upgraded my PC and thus, I can properly demonstrate how the Bloom should look without compromised settings.


I've also made some optimizations after taking @Lee Griggs advice on the ray samples (8 was too high. 3 is good enough for the diffuse and specular. 8 rays should be kept for transmission though).



I'm also in the process of reconverting my old scenes and rendering them with higher sample counts, but in the mean time, I did get to experiment with a simple environment.

4942-optimized.jpg

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