Which first: lights or textures?

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  04 April 2006
Which first: lights or textures?

Which should I set up first in a 3D scene - lights or textures?

I was thinking since the lights would react different depending on the colors and textures on the objects, the lights would have to be last. Also, objects might appear in multiple environments with different lighting schemes, so it wouldn't be necessary to know the lighting setup before texturing.

I'm in a lighting and texturing class, and we're doing the lighting first. And I'm confused.
  04 April 2006
Try to do the shading and texturing first.

If the shaders/textures change later, you'll probably want to tweak the lights again after that.

Jeremy Birn
Author, Digital Lighting & Rendering, 3rd Edition
  05 May 2006
Some materials needs to tweak in some lighting situations, But this is not often that you want to tweak lights for a material. Because light is affecting (almost) the whole scene. IMO this is more convenience to frist create simple materials with diffirent colors then light your scene. After lighting add textures and advanced materials. maybe it would take less time to setup.
  05 May 2006
Thanks guys, I appreciate the info. That's what I figured, but that's not the way we're doing it in class... Would there be a reason to do it backwards for teaching purposes or something? I'm a little confused as to why we're being taught to do it this way.

(Jeremy - thanks for writing your book! Didn't finish it yet, but so far so good! )
  05 May 2006
Different techniques suit different people. I guess if you're just making a still image it's less of an issue.

Lighting and shading should be completely orthogonal. Unfortunately, because we can only really create imperfect models of real materials and light sources, they can't be seperated as much as I'd like.

For animation, it's imperative to nail your look development process before you start lighting, otherwise if something doesn't look right, how do you know whether to tweak your lights or your shaders?

You can have your characters photoreal, fast or cheap. Pick two.
  05 May 2006
There are a few advantages to doing some simple lighting first, just so you have some general idea of how the final image will look lighting-wise before doing your shaders. This is especially true for stills, but also for some simple animations if the camera doesn't move too much.

Like, if you do some simple lighting, you may find some objects are always going to be in darkness, in which case there's no reason to spend much time or any time on their shading. Lighting can be a huge compositional force, and so after an initial lighting pass, you'll have a better idea of what objects are going to be the focus of your piece, and so you can put more time and energy into their modeling or shading.

But it all depends on what your final product will be, and what your workflow is. I generally do an animatic stage before doing a final piece, so I'll do really super simple models, simple colors representing their shading, then do a quick lighting pass, maybe only 1 or 2 lights, then go back and add detail as necessary for the piece. For an environment which is in an animation, will be seen in a number of different lighting setups, etc, it's best to do your shading before your lighting IMO.

- Neil
  05 May 2006
I have to agree that lighting should come first. Just your basic setup; you don't need to get it exact at first. Then do your texturing. Afterwards, you can pefect your lighting with consideration for the materials.
  05 May 2006
I couldn't aggree more with playmesumch00ns. It's really important to get a consistant working environment for all your 3d assets first.

I personally like to have some lighting setup before texturing, if only a skylight and sunlight. The skylight and sunlight are together only bright enough not to cause blowout and not to leave too dark shadows.

  05 May 2006
I guess the issue with this is that you need some lights to see your shaders (unless you are using incandescent shaders only).

I agree it is good to get the shaders consistant as you tend to have the same shaders for several shots in a sequence.

The issue would be do you use a generic lighting setup - eg daylight, or have more specific lighting - ie if you're shot is at night or overcast, or most likely - rimlit.

Most shaders will behave differently if the actual lighting conditions are not very similar to your generic setup, so I can see an argument for blocking out some basic lighting.

However I would love to hear other peoples opinions on this.

  05 May 2006
Originally Posted by tevih: I was thinking since the lights would react different depending on the colors and textures on the objects, the lights would have to be last.

You are correct.

In most companies there are test lighting rigs for shader development, so you can see a shader in a night scene or with rim light and so on while adjusting its look. But shaders and textures are developed first, and (final) lighting goes afterwards.

A part of this is working around the animation: shading and texturing can happen right after models are built, but lighting is done around the animation, later in the job.

  05 May 2006
As a student (assuming you are) you'll be doing quite a bit of back and forth, tweaking shader values, then your lighting...and back and forth. Its part of the learning process.. Don't worry too much about what to do in this respect. Shaders and lighting are completely intertwined, so arguments can be made for both cases.

But for the sake of discussion, I'd like to offer this: You could light your scene using all grey shaders, with some of the material's most important qualities taken into account (I.e, don't assign a grey lambert to what will be a SHINY metal object... start with the proper base shader for that object...Set some shader values that work, just don't pipe in any texture files or procedurals) When you want to focus on learning how to light, this will help you visualize the effects of your lighting, the way your shadows are setup, the way materials can be expected to behave, and also how VALUE in your shot is affected by the lights... Plus, you will be rendering faster when no textures have to load, so you'll be able to noodle your lighting without trying your patience as much.

This approach is also useful when you are learning to use certain renderer features, like FG, GI, caustics, or even tweaking the sampling settings. When textures are out of the picture, you can bet that most of the little noisy bits you see are render setting-related artifacts, for instance, and so you'll be able to learn to optimize them. Keep in mind not to overdo it, however. When textures are introduced, you may be able to get away with a lesser render quality.

I find that setting up as much lighting as possible before setting up all the shader networks saves me a bit of rendering time if I have to do a lot of lighting tweaks to get the right look. Traditional art classes, and photography, usually bring the matter of learning value before learning to render textural effects... So I am pretty sure that the same approach would work for 3D. Im guessing your teacher has the same idea in mind... he probably wants you to be able to do a lot of lighting tweaks easily and focus on value. Hope this helps.

Last edited by daddyo : 05 May 2006 at 06:06 PM.
  05 May 2006
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