Interior Renders with only 'Artificial' lighting (no daylight HDRI from windows etc.) looking very flat!

[Benito Baliti]

I have been rendering quite a long time, but have relatively limited experience with with interior scenes that have no windows and rely purely on artificial lighting.

A current project I'm working on has hallways which are solely artificially lit - and my renders are coming out looking very flat and fake looking. Rendering the same building with the same materials on the ground floor which does have windows yields a much more realistic result. The attached renders are just quick sketchy renders, but for me the difference between them is quite significant.

What can I do to achieve more realistic renders with only artificial lighting?


A couple of issues I have encountered that may be part of the problem:


- Many of the lights are behind some kind of opal shade or diffuser - If I use a 2 sided material, the light doesn't pass through directly and so the scene relies on GI. If I use a mesh light instead, the lamps come out totally overexposed. I know the old school hack of creating an invisible light to provide lighting, but is there a correct way of doing this?

- How to choose the power of each of the lights relative to each other and to obtain a realistic result?

- Using correct Kelvin light temperatures results in super yellow looking renders (which I then have to white balance in the buffer)...am I doing something wrong?!

Any tips or hints to achieve a less flat and more realistic artificial lighting setup would be most welcome!

[Micha]

I would try to add so much realism as possible per good textures and material effects like bump and reflection. For example the floor ground looks strange.

Also different colored lights (line light, spot light) should help.

And there is a repeating pattern at the metal material which needs to be fixed.

Add realistic round edges for reflections on the edges.

Try to use IES lights to get some light effects.

Use emitter textures with gradients for opal shade lights. (You can disable shadows for this material and place a light source inside with a radius for a slightly soft shadow effect.)

[pavol_pastork]

Use emitter textures with gradients for opal shade lights. (You can disable shadows for this material and place a light source inside with a radius for a slightly soft shadow effect.)

This seems to be interesting technique for my interiors. Do you have any render where to see its effect?
Thanks

[Micha]

For example here at the ceiling I used an emitter. If you disable shadows for the material, than the emitter material isn't used for lighting anymore, but a light behind can illuminate the scene. So, you can use a low intensity for the emitter and the emitter object doesn't look burned out. The light for lighting comes from behind. You can use soft gradient for the emitter textures so that it looks like light sources behind a milky glass.(Not so much used at the example here.)

Advantages are: easy and fast to calculate and no burn out effect.

[Micha]

One more idea: use lens effects for glow effects around emitters and add a vignetting.

[pavol_pastork]

Thank you, I test it out in my next project. I render mostly interiors and burnt spotlights emmisive materials are my issues.
I really like your render and lightning. Do you use one or multiple glass planes in windows? Also the sun intensity is amazing - mine is somehow burnt so I turn it off often and light interior only by sun/sky in Dome light.

[Micha]

At my example I used a glass material without refraction, only reflection and an emissive long plane for the landscape effect. But the GI light come from a HDRI environment, because a sky-ground gradient is needed for lighting interiors through windows.

Here is a very old thread where I have shown what it mean. It's one of the most important tricks for interiors. (At the train example not so strong visible.)

https://forums.chaos.com/forum/v-ray...d-photorealism

As sun I used a simple dir light only, it's easy to control and I can easy have different suns for different views.

[pavol_pastork]

Sky-ground gradient in a must, I agree with you. I have to test it. My current fast project interior lightning setup is Dome with sun/sky texture, sun positioning at the top (to not enter directly into room and make burnt spots) and HDRI only as a Background. And empty black Enivronment slot. When I used HDRI as an Environment it always make my render greenish (because most of my sunlight HDRIs consist of green grass with sky). Do you change the environment intensity or hdri muliplier? I always feel that the hdris are way too dark.

I want to my renders be as much realistic (using IES with intensity set in lumens) but I think I miss some overlooked detail or another approach. My renders looks like these:

[Micha]

Yes, I adjust the environment intensity. Also, it can be useful to change the color mood per color gain option of the texture. So you can quick adjust the mood. For example at your first rendering I would try to add more blue at the exterior HDRI and more warm lights at the interior. Color contrasts are nice often.

I know the problem of the greenish look by a GI HDRI with grass lane too. You can desaturate the green lane of the HDRI before you use it.

Attached one of my basic GI environments. It's one where I try to keep the color impact to the scene low. My train clients don't want to get to much color by the environment because the color design must be kept. For mood shots a more colorful GI HDRI can be used.

Sidenote: funny is to setup a light like a flash light of the camera. This can add realism, since nobody expect that a flash light is be used at virtual scenes. I used it very seldom, but some times I add it as fill-in flash. Here a basic example I found at the web:

https://assets.3dtotal.com/data-impo....image.q5x.jpg

[pavol_pastork]

Thank you for great tips, I will test it in next project. Desaturating GI HDRI before use was that another point of view..... Sometimes we all need to think outside the box.
Setting of flash light of the camera is simply wow....to get even better results one can put 3d person behind camera (just for reflection as there is a real photographer, or maybe some tripod with camera)....

[Benito Baliti]

Thanks for the great tips! But you didn't really answer the question I asked!

Like I said these are just sketch renders and have a few textural issues for sure (eg the weird texture on the metal turns out to be artifacts from making a strip light too long!) I am not concerned with the minor details at this stage, just the light main lighting setup.

It is the flat look which I am trying to fix. Do you have any examples of interior renders you have done that are solely lit by artificial lights?

[pavol_pastork]

My bathroom render which I posted yesterday is imlinated by artifical lights only. There is no windows or daylight. I used 2 IES lights and Emmisive material for mirror.

[Micha]

Here two renderings of small rooms without daylight: important is to use different colored lights, also slightly different.

[Benito Baliti]

Thanks Micha, those look great!

Could you maybe briefly explain your lighting and camera setup in these renders?

- Is all the lighting coming from the light fixtures or do you have additional invisible lights to add light to the dark parts?
- How do you get good light out of the main light in the first render? Is it a light behind a diffuser?

Well done, these are very nice renders!

[Micha]

I use emitters for the direct visible lights. At the first rendering there is a rectangular light in front or behind the ceiling emitter light. Yes, if needed I use additional invisible lights, for example a spot light to get some focused light to wash basin and toilet.

Also often I use emitters for not so bright effect lights like the blue light above the wash basin desk.