Wow, extensive reply. Thanks for all the info, seems like the logical way to
approach it…
From: [email protected]
[mailto:[email protected]] On Behalf Of [email protected]
Sent: 27 February 2014 11:02
To: [email protected]
Subject: Re: Reverse lighting - how to convert CG light setup to live action
setup?
I’ve attempted this - sort of. It wasn’t live action though, rather live
spectacular / theatrical.
The idea comes up once in a while, to match what’s happening on stage with
projected imagery. It starts with good intentions, a bit of fiddling, and ends
up with an impatient creative director deciding they can’t afford any time and
they light the whole stage pink while the background imagery is blue, and say
that it works “artistically”. And to a degree it does: usually the director
wants the actors to really stand out on stage, not to blend away into the
background.
But if realism and believability is key that’s not going to fly of course. Much
boils down to what is going to be shot: is it actors on greenkey to integrate
in your CG background, actors that have to match a CG creature, a partial set
that has to match a CG environment? It all seems a bit backward – but it might
very well make sense.
A sit down with the DOP to know what info he needs is probably the best
starting point.
What I’d do (if they are serious about this) is:
check if the CG lighting makes sense physically - no lights without shadows
going through floors and walls for instance.
if things seem impractical, amend in CG first (lights floating 30 meters high
in the air, special shadow geometry,... don’t use “big” omni’s – it’s okay for
small light bulbs or a candle light – but studio lights are usually spots )
separate between direct (spots) and indirect light (hdr) - make a series of
images, one light at a time, to show what each light does, in order of
importance. (key, fill, rim...)
When I say one light, I mean one layer of light, it’s possible that you have
ten lights of the same color with tweaked intensities and placement, just for
the keylight – they don’t need each individual one.
Reduce things to what’s essential. If you have a couple of beauty lights just
for some individual background objects, they probably don’t need those.
For colors, ideally they need to know values in Kelvin if you used them, or the
realworld light you tried to replicate (daylight, office fluorescent,
incandescent bulb, candle,...)
For other colors they would need to use colored gels but that’s for very
saturated colors only - they cannot choose every color in the color wheel for
lights.
You should provide printouts of top and side views – showing placement of
lights, camera/s and subjects. You can work out most from the top view /
floorplan, but side views help to figure out elevations. its mostly figuring
out angles, directions, relative intensities, shadow softness and colors.
look at the result from the HDR seperately, is it soft fill/bounce light of
certain colors? how important is it (intensity) compared to the direct lights?
chances are that matching the direct lights is enough, as bounce is going to
happen naturally anyway – unless you used the HDR in a very “showy” way. In
which case: good luck – you could try to convert it to a direct light rig - If
there’s a few very obvious main lightsources in the HDR it might work out. If
your HDR is really important for the look and is some physical location than by
all means show it – there is information to be had there: what kind of sky,
floor, where do lights come from, what is there to produce shadows?
Be very patient when trying to communicate all this – as you’re bound to have
very different vocabulary.
In my experience, giving a ton of information that’s relevant in CG but not so
much in real life can end up counterproductive – it’s going to look too
complicated and overwhelming – and they will end up abandoning the whole idea
and just light it as usual and have you match it after.
So make sure that you have clear, simple information going in and that you
understand very well what each light does, what purpose it serves. Because
that’s what you need to get across. It’s an overall effect you’re after and you
need to understand how it’s built up in order to communicate that and have it
replicated on set.
eg: there’s three lights that matter – first is the key, comes from camera
left, very lateral, high intensity, harsh shadows, warm/incandescent color.
Second is a soft bounce from the floor, has the color of wooden floor. Third
is a rimlight / backlight, coming from the right, from 45 degrees elevation to
overhead – it’s cool, daylight, and about half the intensity of the key.
Not an exact science, but something they can work with. And by all means keep
the overload of detailed info at hand just in case.
From: Neil Kidney <mailto:[email protected]>
Sent: Wednesday, February 26, 2014 12:49 PM
To: [email protected]
Subject: Reverse lighting - how to convert CG light setup to live action setup?
Hi list,
Anyone ever had to give a CG light set up to on-set lighters?
I need to deliver the light set up from a scene lit with spots and HDR so it
can be matched on set.
Cheers.
