How would you light this?

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NStocks
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Joined: Tue Jun 19, 2018 4:55 pm

How would you light this?

Post by NStocks » Wed May 04, 2022 7:20 am

Hi,

I'm looking for ways to provide natural light appearance in a project that is esentially a polycarbonate shell over an existing brick building. It's rendered in easy-09 due to the advanced material on the corrugated polycarbonate.

The render will need a lot of background images for landscape etc, and so no lighting can block out those elements. I'm also thinking very soft shadows so the sun will likely need to be enabled. I will be producing interior and exterior images but internal ones are naturally darker due to less light inside.

Initial thoughts are fake emitters - sky portals aren't likely to be helpful on this one... The image below is a first quick render of the interior.
Screenshot 2022-05-04 at 08.17.59.png
Screenshot 2022-05-04 at 08.17.59.png (1.89 MiB) Viewed 8529 times
Screenshot 2022-05-04 at 07.56.20.png
Screenshot 2022-05-04 at 07.56.20.png (2.41 MiB) Viewed 8529 times

Fletch
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Re: How would you light this?

Post by Fletch » Wed May 04, 2022 10:42 am

It's all about Post-process
You must adjust post-processing while it is rendering, or before you close the render dialog while the image is still there
But since you have Twilight Pro, you can open the image in History dialog and adjust/save from there.

I would start with a good Spherical treeline sky, and sun as you have it set. Then I would click Post-Process button in the render dialog and choose "ACES" and adjust "Exposure" up until I'm happy. Exposures to try: 1.25, 1.5, 2, 3, 5, 10, 20, 50

If you don't like results from ACES (automatic version of Filmic and pretty good stuff), then you can try Filmic. Start with setting exposure to 1, or 1.5 or 2, and keep adjusting Filmic settings until you're happy... definitely read my links below for more about adjusting Filmic settings - details in "Filmic versus ACES when Tonemapping" thread below are going to be very helpful.

ACES, (Academy Color Encoding System) is currently a default tone mapping curve in Unreal Engine 4. ACES color encoding system was designed for seamless working with color images regardless of input or output color space. It also features a carefully crafted filmic curve for displaying HDR images on LDR output devices.

Read more about Filmic and ACES here.

See these tutorials:
Twilight Render Post Process
Subject: ACES vs Filmic : When do I use Filmic versus ACES when Tonemapping?
Filmic or Aces? These new tone mapping algorithms are so powerful - Copper Cookware Scene

NStocks
Posts: 71
Joined: Tue Jun 19, 2018 4:55 pm

Re: How would you light this?

Post by NStocks » Wed May 04, 2022 10:10 pm

For lighting, other than the sun, would I be better to use multiple fake emitters instead of a giant single sky portal, given that the entire project is essentially one huge transparent box itself?

In this interior scene which receive little light due to a first floor, I've placed two fake emitters opposite each other - slightly too bright but it helps a lot with the lighting... Should they be placed as I have them, or instead be placed underneath the floor above, acting as a Lightbox into the space? It's quite a complex scene with a lot going on!
Screenshot 2022-05-04 at 23.13.48.png
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Screenshot 2022-05-04 at 23.13.58.png
Screenshot 2022-05-04 at 23.13.58.png (1.77 MiB) Viewed 8497 times

Fletch
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Re: How would you light this?

Post by Fletch » Thu May 05, 2022 10:33 am

Sky portals are useless in your case, as they are only useful when you can use them to focus light through a single opening.

You should rely on physical sky, or HDRI, or a good treeline spherical sky and the sun. Render on Easy 09

Do a search for polycarbonate on this forum to find some materials people have done, I believe Massimo or maybe Alvydas created some nice renders.

I would possibly add invisible (not "fake") emitter planes just below the ceiling where the translucent ceiling is to help the interiors render more quickly. I wouldn't place big invisible emitters on the walls as you show because no light would normally come from that direction. I would possibly add a "helper" invisible surface emitter again under the lights that are supposed to be lighting the space in order to push more direct light in, but not to boost lighting in the space because of lack of lighting. If the space lacks lighting, then it will be dark in real life. If you have adequate lighting as if it's a real life space, then all you need is to boost tone mapping with the exposure as I said above.

See how the rendering below appears very dark until the exposure/tone mapping is corrected?

Image

See here you can also boost exposure very high (20) and maybe bump the gamma to 1.1 if necessary.

Image

All that said, I have been known in the past to add some "helper" fill lights as emitter planes, as I did here:
Subject: Jubilee Church - Revisited Image
That was to get the noise to clear up faster, as direct lighting clears up much faster than indirect lighting. But now, because I use the Fastforward AI Denoise addon for Twilight, the image is instantly noise free, and renders 4x faster than in the past, and I don't add those helper emitter planes any longer.

NStocks
Posts: 71
Joined: Tue Jun 19, 2018 4:55 pm

Re: How would you light this?

Post by NStocks » Fri May 06, 2022 7:41 am

When I use invisible emitter near windows (outside or inside), they block out the direct sun rays in Easy 09 with HDRI. Is there a way to prevent this from happening?

Fletch
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Re: How would you light this?

Post by Fletch » Fri May 06, 2022 8:17 am

Maybe you accidentally disabled the sun when you loaded the HDRI environment?

Emit: Invisible does not block sunlight/shadows from the sun.
Try attached test scene to see for yourself. :hat:
Attachments
emit-invis-test.jpg
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