Any Tips on Balancing Exposure?

[charles_messenger]

Does anyone have any tips for keeping exposure balanced with interior renders? I've tried several different methods including duplicating the dome lights and setting one to invisible and the other not not affect diffuse, shadow, reflections etc. This kind of works but seems like a long way around. My issue is that it seems any bright spots like exterior views through a window, or any areas close to light sources clip very easily. I've tried combinations of Filmic tonemapping, aggressive curve layers, and exposure clipping layers, but these seem to all make the image come out flat looking.

I have a background in real-estate photography and am familiar with exposure bracketing and HDR processing, but I would think that with a digital rendering with exponentially more data than a photograph, I would be able have a softer transition to the highlights. Would 32-bit PNG rendering help with this? I currently save out renderings in VRIMG files, adjust exposure and curves in the VFB and then export 8-Bit PNG to lightroom / Photoshop for further editing.

[vladimir_krastev]

Hi, you should not be doing any major (if any at all) corrections to the images once you are in 8 bit. EXR is a good format to work with in photoshop. Could you share some visual examples of your work?

[charles_messenger]

Hi Vladimir,

Absolutely agree, the only post corrections are VERY minor once in 8-bit mode. Mostly just contrast and sharpening adjustments, but nothing in the way of exposure.

This was a recent project where I ended up just leaning into completely blowing out the highlights, even though there is still some data in the sky that I would have liked to recover in the final image.




When pulling the exposure back about 5 stops, you can see there is some detail and color in the sky.


Hope this helps with what I'm talking about. Another thing I always find tricky is if there are any sun rays coming into the scene the always clip the highlights so I usually end up having to really tweak the sun and sky light dome and multiply the sky by 5x and reduce the sun intensity by 1/5 or more. Is that normal?

[vladimir_krastev]

The question about over exposed windows is an old one and it has no definitive answer.

If the room is too dark then:
- leave it like that (most physically accurate)
- add artificial lights behind the windows and other crucial places (photographers do that when possible)
- create some fake stuff with the sky like two domes, use one for GI only, etc.
- do some fake stuff in post production (push the exposure high - not a bad method if you have low noise and 32bits)
- use VRayOverrideMtl to boost the GI in the room and to make it white (especially useful for dark colored ceilings like yours).

Your camera is looking straight into the bright sun behind the windows it is natural to have overexposed windows.
The furniture is lit from behind relative to the camera view so high contrast and burned/dark areas are expected and this is true for any real life camera.
V-Ray recreatest a real camera in the virtual space.

[charles_messenger]

UPDATE: I've been experimenting with using more aggressive curve corrections and I think I've gotten the results I was looking for!

I've stretched out the highlight portion of the curve map to about +5.0EV and flattened the top off almost like a really strong filmic curve. It keeps the exposure even throughout and doesn't clip any highlights. It also doesn't seem to affect interior light sources much, since the sky dome light is exponentially brighter.


WITH CURVES:


WITHOUT CURVES:

[suzanne_doherty]

I'd personally say your render in your 2nd post looks more realistic and photographic than the ones in your last post. You've really lost your contrast, shadows, etc in the latest one.

For me, I'd generally control the exterior in post, and would likely swap the rendered background out for a photograph, and adjust then. However in this situation, where you have relativly small windows, I'd still expect the exterior to be blown out.

[vladimir_krastev]

My favourite is this one



Maybe it is lacking contrast a little but this is easily fixable and a matter of taste. Otherwise it is balanced and in my opinion more realistic looking.
This is not only because of the use of curves but mainly because you changed the direction of the light. It is much better now, softer and falling at a nice angle.
In the previous version it was glowing almost straight towards the lens of the camera which presents a challenge in photography and rendering.