Some questions regarding Lighting application in 3d animated films

[MoZz]

Hi,
I'll try to answer to some of your question... but I look forward to hear something from people with more experience!

1. I think there is no need to use any kind of decay for sunlight, except if your trying to reproduce some kind of mood.

2. As probably you know, the backlight is usually used to help defining shape and make the scene easyer to read. The image you posted is very contrasty and you can easily recognise all the shape and the object present on the scene. However you can use some backlight to simulate light bouncing from any surface or emitted from a window or some other object. This will help if you want to stick out something and make it more important in the scene.

3. I don't know the render engine used on Monster House and probably I'll be wrong, but I think a lighter should have much control as possible on what is happening in the scene. Using a render with bounce light is very helpful and save a lot of time (except in render time) but I think it's just a good start. You should always improve the scene using the traditional way of lighting depending on the feeling of what you are aiming for. This give you the full control on your final result.
It depends also on the film however. On Happy Feet the choice of using traditional light instead of GI was just because there was no need of it. I think it wasn't useful using Gi on a movie where the main ambient was a big open space, without so much bouncing through different materials or color bleeding. It was very different from Monster House where a lot of shot were indoor and I think the GI helped a lot the lighter to arrange the scene. But, I repeat, I think they worked later with other lights to reach the right mood.

4. In my experience, the light angle was always adapted when needed. Sometimes happen to light a shot with a char that doesn't catch any light that delines his shape, with the consequence to have a char really flat. In this case, if the scene allow you to do it, you can cheat a little bit (without change completely the base light) and move the light to give some shape to the char.

7. I think the most common way is to have a general light rig for all the char present in the scene and then different set of light for each char. I usually try to reach a good balance for all the char using one light rig for all of them. When I'm satisfy with the result, I start to refine each char with additional lights.

I'm really interested on other people's opinion....

... and sorry for my english :)

Ale

[mr Bob]

6) Becoming a lighter
While looking at film credits on IMDB, I noticed a lot of lighters came from a compositing background, why is that?

why ? because in major feature pipelines as much as possible is automated ! and 90% of the work is done in 2d !!!

B

[playmesumch00ns]

3. I thought Sony bought Arnold for Monster House. Even with loads of GI and everything there's still a hell of a lot for a lighter to do! You still need to light a scene creatively, in the same way a DP would on a film set.

[israelyang]

Ale
Thank you for your answers, I like your answers especially to 7)
And your english is fine :)

mr Bob
I am sure a lot is done in post, such as xyz pass, normal pass, I am not sure about the percentage though :)

playmesumch00ns
This is what I want to know though! I am so desparate to see someone take the above images or other stills from an animated film and explicitly show us what other additional lights the artists place other than the obvious visable light sources (i.e. the sun, the table light, the street lamp...) to make the image more appealing.
Or someone to tell me, yes, one sun light is all they used for the exterior scene, or no, one sunlight is placed, but then a light here above this house for this purpose.... I just don't want to feel like i am missing out essential lighting decisions that many of us overlook. or if I am over complicating things? Can live action lighting setup be completely translated into 3d production with a GI renderer?

thanks

[ExP]

israelyang, it feels to me that you are slightly over complicating things...

On a general note, keep in mind that especially in 3D animated movies the final goal is ALWAYS the artistic vision behind the story.
That's why in many cases filmmakers don't rely too much on accurate lighting simulations. They just use what works for the shot in order to tell the story.
You mentioned about the lighting changes from shot to shot. If you pay close attention, that happens all the time in live action films either. A DP is usually not too concerned as to keep his lighting consistent, but rather to make each shot look the best, and most of all, reflect visually what the story is portraying or what the characters are going through emotionally.

Now on VFX that is somewhat different. Most of the time you're trying to implement a CG element in a live action BG plate. And that's where an in-depth understanding of the physics of light and how nature works come in handy. But that of course doesn't mean you have to be chained by those laws.
At the end that's what movies are about... not a mere reproduction of life, but an orchestrated interpretation of it.

Now to go back to your question "what's left for the lighters to do?" the answer in my opinion is just that: Take what would be a “physically accurate” lighting set-up and orchestrate it so that it supports the story, the characters, and the filmmakers' artistic vision.
That is the fine line between art and science.

Hope this helps.

[israelyang]

Exp
Thank you for your reply and it has indeed help. Every once in a while, I find myself in an ivory tower and need to be snapped back into reality.

I have fallen into the pit thinking if I have only used one light for a shot, even though it looks good and fits the scene, I fear that I haven't done my job and doubt myself as an artist/craftsman.
But looking at great photographs, aren't many of them them taken under the natural lighting environment, with just the sun, or the moon, and no supporting artificial lights? shouldn't they have been solid proofs that, sometimes things don't need an extra hand.

The answers are becoming clear to me, thanks.

Though I still welcome people to address some other specific questions I have asked.

[mr Bob]

How about you throw some of your shots up so we can have a look ... must admit I do find it tough to sit around trying to work on stuff from home , the rule whatever has to be less time dreaming more time DOING ! .Even if you make small set ups like a bunch of teapots etc to demo your lighting ideas. Im doing smething similar while I dig into renderman.

B

[israelyang]

I did a full CG shot for a movie, it turned out well and people who saw it thought it was very realistic. And I guess it becomes somewhat awkward when I show it to the recruiter for a lighting position, and all I can talk to him about the lighting setup is that it's '(just) one key light and IBL'. However good the shot looks, all of a sudden I feel like I don't have enough credit as a lighter. What a dilema!

mr Bob
I would be delighted if you could give comments on my stuff. (Everyone feel free too)
Currently I only have a couple shorts to show that I did back in school, some of my professional projects are still under NDA.

* 10 second short, click on the orange 'download' button
http://www.savefile.com/files/732875

* Thesis film
http://www.reveal.ea.com/reel/Israel.mov

* My lighting challenge submission on CG talk (where I did the lighting only)
http://img178.imageshack.us/img178/7130/25stk3.jpg

* Lighting for the top 2 shots (actually I did next to everything for the second shot) on this site (my former employer)
http://runeentertainment.com/

* for stills please see my cgtalk portfolio


Most of my questions came up 'while' I was 'doing' stuff, but as you probably understand, most of the time at work, the timeline is always short and sometimes when a question comes up, you have to put it aside. And it gets tough when no one around me is interested in lighting and I resort to books, internet reading and forum like this.

Now that I am looking for work it gives me the time to gather my thoughts and questions that have come up during production, but did not have the time to clear up or straighten out.

[ExP]

israelyang, by looking at your samples is seems clear your questions fully reflect your work.
In my opinion you show some great technical abilities, but you fall a little short in your storytelling skills.
You were talking about how many lights to use and which GI technique is the best, but if I were you I would try and focus a little more on communicating emotions thru light, color and shadow.
As one of my mentor told me, learn how to "write" with light.

As an example, in your CGtalk Challenge pic, you show your technical lighting abilities, but to me the image does not communicate much.

Here's something you can try:
Take a setting you like; it can be something simple like a character sitting in a room. Now write in a couple of pages a whole back story about that character... where he/she comes from emotionally... some difficulties he/she has to face... what he's thinking about... etc... Now tell ALL that with the way you light the room. You just need one frame. No animation.
One more thing... don't worry too much about where the light comes from logically of if it is physically accurate.

Cheers.

[israelyang]

Hi ExP
Thank you for your honest comments. It's nice to hear so I can improve on it.
My strength lies mostly in 'observation interpretation' from direct observation. I can look at an image and generally tell what's missing and make it more artistically pleasing, but designing from blank paper is not one of my strong points.
I am reading Robert McKee's 'Story' and 'Painting with light' by John Alton, hopfully they will help me hand in hand.

P.S. I don't think I asked which GI technique is the best though.

[anty]

Hi
Actually Gi can't change nothing in production, just check how many interior renders done with GI, but not all from them looks nice, just few really talented persons render great looking interiors with interesting light. As for Gi and lighters work - ha - U can use just skylight+ sun, but it's work fine only in simple scenes, and no artistic filling from image.
To make scene realy interesting to look, just think - how you can make it's more deep, and from this point your work start again)) So no reason to warring))
And small hint with GI lighting- always experiment with temperature and tone of lights, it's really make frame alive)) For example - U have some lamps over the wall, if all of them fill walls in same color and power - u see the fake, if U change coloring and power just on few lights - it's can improve boring looking image and make it more live. So my point - just play with light and watch the world around you, and don't think about rules)) Fill free to light) Like aqua paint :)

[israelyang]

Hi anty
Thank you for your reply and tips, I appreciate it.

However I hope people can read about my post more carefully, I really have no problem with GI (and said I do not want this to turn into another GI argument) and am fully aware the fact that GI is not a one button solution.

I was simply puzzled by the comments made on the Monster House DVD commentary, where the lighting setup sounds very simplified, and I highly doubt it's that simple (considering the number of lighters for the film). So I was looking for some credited voice to either confirm or oppose my doubts, and give an example.

[anty]

I see your point)) I gues lighters have to think now not how make light bounce)) But more - how to make it's more artistic, intresting and so on))
Btw - photography not killed traditional artists and traditional painting)) And cheap digital cameras can't make all around who make photos an artist))

[Amaan]

hello... this seems like a cool discussion, so I thought I'd post my humble take on some of the issues discussed here. I find your thoughts into lighting approach very interesting... i hope the following will be of some use

1) Light decay rate
Doesn't matter on planet earth. the sun's far away and an inverse square curve becomes pretty flat as it travels along its journey on the x-axis of a graph. Inverse square law is more of a mathematical model for light falloff, but in real life even our own eyes tend to 'bend' this law as they are more reactive to darker shades of light. So while inverse square falloff is important, it's not always what gives us a 'realistic' result.

2) The use of back light/rim light/kickers for a naturalistic lighting scenario
backlighting often comes in in the form of an actual light source, or as a fresnel reflection. In real life, all objects reflect light and posses some degree of fresnel-like reflectance (either metallic or fine-dust-on-edge) and hence in CG often this 'backlighting' comes in to play some kind of a role to make cg things more believable. I often end up using it as either reflection, or as a light.
Backlighting can, as already pointed out, be used to enhance compositional separation between scene elements--the trick is to use it according to the scene's design. too much can often give a theatrical look.
Providing backlighting is to me of secondary importance--that is, I add it if I think a scene needs it, or sometimes I will add it in anyway and then evaluate how much it is adding to a scene. I will remove/tone-down if it is in anyway giving extra importance to background elements that do not need to stand out and detract attention from the primary foreground element

4) Light angle from shot-to-shot
Happens all the time :) Like already mentioned, the trick is to get the shot to look its best but without breaking the feeling of continuity between the look of shots. The average person normally does not take any notice

6) Becoming a lighter
For me, lighting is all about colour/contrast and these are elements that compositors play with all the time, even when working with real footage and combining multiple elements from separate plates into a single shot. Good compositors develop an eye for knowing what looks just right and often very quickly get an idea of what kind of lighting they would need in a 3D plate to get their final comps looking just right. Also, compositing is about making a shot look 'cool' while playing with grades, and often we as 3d lighters end up doing the same by dialing in different lighting combinations until everything looks just right in a scene. There's a lot of common ground here... often when I am lighting I know how much I need to push my 3D lights to make them ready for the compositing stage, where I can get a nice final look done via multi-pass rendering. The goals are the same. There is a lot of crossover between lighting artists and compositors in both directions.

7) A separate character light rig
I do a basic light rig for all the scene elements (usually a fill light only pass), and then start dropping in more specific lights to make the elements work better compositionally

-amaan

P.S. Painting With Light is one of my favourite lighting books :)

[israelyang]

Hi Amaan
Thank you for your lengthy reply, I have visited your website before and appreciate your tutorials.

I would like to address your answers for 2) and 7)


2)
All-for-the-look approach probably will mean adding any lights necessary to make the scene look good, i.e., adding a kicker to create a nice silouette even though there is no such light source in the scene?

If you have your Painting with Light book with you, please turn to page 51, Lighting a campfire scene, you can see there is a campfire, as the main key light source, 2 front lights on each side of the camera to illuminate the faces of campers facing the camera. AND 2 strong backlights. I can easily accept the use of all lights mentioned here, but the 2 strong backlights. How do we justify them, or we simply don't?

7)
Here are 2 images from Monster House (sorry I keep using their images, it just happened that i took some screen shots of it)

http://img522.imageshack.us/img522/8710/75045493aw1.jpg
http://img513.imageshack.us/img513/8282/74253567kf0.jpg

you can see the 2 hero characters running in and out of the tree shadow on the street, and yet the lighting on them stays the same through out.

I have worked on projects and heard of other projects where the lighters only light the set and the main characters use their own exclusive light rigs, what do you think of this practice?

[MAV4d]

The easy way to justify the 2 back lights could be photon reflection, everything accumulates light and reflects it (therotically) IE moon light Camp light Star light ect... and that could be the simple answer to back lighting


but its usally just there from an artistic stand point. Someone once told me that a night scene should never be underlit. sounds contridicting doesnt it. Esp if you go out side where there are no lights and lets say cloud tree cover, u can barely see. people feel different in the dark and so i think the use of backlight is simply a comfort techinique used by cinematographers to set the mood.

but hey i dont know too much and this just my oberservation.

Please disregaurd all spelling, i am quite horrid at it

cheers

mav

[israelyang]

thanks for your reply

[israelyang]

Hi everyone
I just read this siggraph course today
http://www.siggraph.org/education/materials/siggraph_courses/s96_course30.pdf

and in particular, Sharon Calahan's part answered most of my questions in my post. In reading John Alton's Painting with Light, it's helpful but Calahan's article addressed many of the modern day lighting issue in its CG application. I am very glad and appreciative to have read it. And I urge anyone with an interest to read it as well.

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