Mimicking infill lights to balance daylight

[rjohnson33]

I'm currently struggling with the lighting of some pretty small hotel rooms that each have a 1.2m square window
as their only natural light source. My initial approach was to use Reinhard Colour Mapping and gamma 2.2 baked in
to get exterior light (HDRI dome and skylight portal at the window) into the space while avoiding burn outs.
The issue with this is a lack of contrast which I can't seem to coax back in Photoshop in any sort of natural looking way
and the client commenting on washed out and pale colours despite me having upped saturation values on materials
beyond what I feel is physically proper.

So I'm thinking to myself can I approach this in proper linear workflow (no Colour Mapping, gamma applied in post)
and do this like a photographer would? I'm guessing you would choose an exposure value for your camera so that
the daylight/sunlight wasn't over-exposing the scene too much and then take it from there to add other light sources
within the room to infill.
I've approached this by using vray-plane lights at present but I'm not sure whether to switch off various elements
such as cast-shadows, affect reflections or affect specular. Obviously if I were going for a real life simulation I
wouldn't have those options but I don't think I want to end up with lots of criss-crossing shadows and dozens of highlights.

Does anyone have any tips or maybe some links to good reference material/books that focus on the subject of photographic lighting set-ups?
I've been looking at a studio lighting rig for vray sold by the agtool company. I like the sound of adding some variance to the lighting sources
but is it worth it to go to this much effort or will the effect of those rigs just get lost?

Just as a side issue with this process: I'm looking forward to being able to properly composite my image from render elements for once
due to using totally linear workflow (this doesn't seem to work when using Reinhard Colour Mapping for whatever reason).
If I use sub-pixel mapping and/or clamp output when rendering will this also stop my composite from turning out correctly?
(i.e. matching the beauty pass)
I can't seem to manage without these features at present so I hope not.
Or maybe those 'shiny' pixels won't be as much as an issue with lower dependance on the sun for exposure?

[JeffG2]

Can you post images of what you are currently getting from your set up?

[rjohnson33]

I can post just this one. This is the raw render



Actually this is the more forgiving of the rooms as the windows in the others are half the depth but I still think there's a general 'flatness' in the tones here
despite some of the saturation values in the colours being incredibly high. Maybe you can sense that in the chair!
Reinhard is set to a burn value of 0.2, camera is at f4 - ISO 100 - shutter speed 1/0.75. There's a single HDRI in a vray dome light
and a straightforward plane light just off to the righthand side of the camera set to a luminous power of 1500 lumens.

Bringing back contrast and saturation in photoshop just don't seem to be having the desired effect.
Maybe I'm being fussy but I thought it might be interesting to try setting this up as per my original post and seeing the difference.

[yyk]

I think you're making this far too difficult for yourself. You've got a window on the left side which gives you an opportunity to use sunlight, and two lamps by the bed which would give some color to the shadows. Why do you insist on using fill lights and gamma 2.2?

[simmsimaging]

Approaching it "photographically" is probably a bit more deceptive than you might realize. A pro photographer would/could approach that kind of lighting situation a number of different ways, but in this era you can be sure many if not most would realy on compositing multiple exposures to get the right look.

In your case I would suggest you decide in advance how much exposure control you want in the window - if you want to see detail in there (of any level) then set your exposure by the window and fill the room to match. The old school way (photo) might have been to use neutral density filters taped to the window to bring that value down a bit, but as it is a key light source you don't have a ton of option except to balance exposure to that.

Using large pure white light sources will always give you fairly blah lighting in a room ful of diffuse materials (bed/walls/upholstery etc.). You might need it for overall fill, but if you want to get away from the flatness issue you need to add more directional light, and probably some smaller and harder lighting sources.

Adding some of those lights with different colour balances (e.g the nightlights can be on and use a warm colour temperature) will also help add some variety and depth.

Bear in mind also that much can be done in post, and photographically very often is, but it will need to be done selectively, not globally to add depth and contrast (e.g toning down one wall and the side of the bed to add direction to the light as well as contrast, rather than just level/curves to the whole thing -- etc.)

Last: I believe that you can't use Vray tonemapping like Reinhardt with linear. That only works on non-lwf images. If you want linear then you need to do the tonemapping in post.

/b

[rjohnson33]

I think you're making this far too difficult for yourself. You've got a window on the left side which gives you an opportunity to use sunlight, and two lamps by the bed which would give some color to the shadows. Why do you insist on using fill lights and gamma 2.2?

Ville, yes I probably am making it too difficult but thought it was an interesting enough topic even so!
I hadn't utilised the bedside lamps up to this point because I thought they might look strange being visibly on in what was meant to be a daytime situation.
Ignoring that for the purpose of discussion are you suggesting that with the daylight from the window and the two lamps activated I could get a good result for the room?
I'm guessing from your gamma 2.2 comment you would do this entirely in LWF (gamma 1.0 and no colour mapping/clamping)? What software do you then use to apply tonemapping in post?
I like the look of the interiors in your portfolio. Could I ask if these were generally acheived using these methods?

[rjohnson33]

Approaching it "photographically" is probably a bit more deceptive than you might realize. A pro photographer would/could approach that kind of lighting situation a number of different ways, but in this era you can be sure many if not most would realy on compositing multiple exposures to get the right look.

In your case I would suggest you decide in advance how much exposure control you want in the window - if you want to see detail in there (of any level) then set your exposure by the window and fill the room to match. The old school way (photo) might have been to use neutral density filters taped to the window to bring that value down a bit, but as it is a key light source you don't have a ton of option except to balance exposure to that.

Using large pure white light sources will always give you fairly blah lighting in a room ful of diffuse materials (bed/walls/upholstery etc.). You might need it for overall fill, but if you want to get away from the flatness issue you need to add more directional light, and probably some smaller and harder lighting sources.

Adding some of those lights with different colour balances (e.g the nightlights can be on and use a warm colour temperature) will also help add some variety and depth.

Bear in mind also that much can be done in post, and photographically very often is, but it will need to be done selectively, not globally to add depth and contrast (e.g toning down one wall and the side of the bed to add direction to the light as well as contrast, rather than just level/curves to the whole thing -- etc.)

Last: I believe that you can't use Vray tonemapping like Reinhardt with linear. That only works on non-lwf images. If you want linear then you need to do the tonemapping in post.

/b

Brett, thanks for that advice. It will be useful and I'm suffering from a lack of actual photographic experience obviously!

Again, as I mentioned in my previous reply, I had imagined that seeing those bedside lamps on with broad daylight would appear strange
but as you say adding more directional lights with different colours should help to create a bit of drama.
Perhaps the situation would better suit dusk or twilight exterior lighting.

Could I ask what software you use for tonemapping if it's a familiar part of your workflow?

[yyk]

Ville, yes I probably am making it too difficult but thought it was an interesting enough topic even so!
I hadn't utilised the bedside lamps up to this point because I thought they might look strange being visibly on in what was meant to be a daytime situation.
Ignoring that for the purpose of discussion are you suggesting that with the daylight from the window and the two lamps activated I could get a good result for the room?
I'm guessing from your gamma 2.2 comment you would do this entirely in LWF (gamma 1.0 and no colour mapping/clamping)? What software do you then use to apply tonemapping in post?
I like the look of the interiors in your portfolio. Could I ask if these were generally acheived using these methods?

Yeah, you're right about the lamps looking a bit out of place when lit in a bright daylight setup. Maybe a dusk mood then? I usually use exponential color mapping, gamma somewhere around 1-1.8, it's just a personal preference of course but I find it gives best depth and color to the lighting.. I don't do much tone mapping in post, just basic level and color balance adjustments. I hear what you're saying about mimicking a studio light rig.. it could be a fun process once you get all the pieces to fit. Good luck, and post your progress!

[simmsimaging]

It's not that unusual for lamps to be lit in interior shots, but whatever works for you aesthetically is workable as long you get the lighting you are after.

I do the tone mapping Photoshop - mainly be manually adjusting exposure and levels selectively. Occasionally I use something like Photomatix but only when going for an effect.

/b