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View Full Version : Is global illumination in or out?


seigi009
11-24-2003, 11:42 PM
I know that global illumination looks really good, and can make your work shine. but does anyone think it is over done. Let's say I am making an animation for a demo reel and am considering using it. Is it common?

fxjeane
11-25-2003, 03:42 AM
Depends said the wise man!.

If you are looking for a job as a lighter and all your job has "brute" GI, I dont think people will be impressed with you. If you are looking for a job as an animator and dont want to spend hours tweaking controls, then yeah, go ahead and use it (if you really can afford the render times).

I think GI has its place in prodcution nad a time will come where it is as common as raytracing. Untill then, skilled lighters will be in high demand.

Cheers
Rudy

Andrew W
11-25-2003, 08:28 AM
I think it depends what field you want to go into. If you're an animator then no-one is going to care what the lighting looks like, frankly; if you want to be a lighting TD, then it does matter a great deal. For most feature work, and I guess TV work too, you won't get the opportunity to use GI simply because of the amount of complexity that makes up the average VFX shot precludes its use.

The bottom line at a studio is "Can you make this render beautifully, at 2K, in between 20 minutes and 2 hours a frame without crashing the render farm? Yes or no?". It really is that simple. At the moment if you use GI then the answer would be "No" , but as machines become faster, with more RAM this will be less of an issue.

I would suggest that if you sent a lighting reel to a studio, that only had GI on it you wouldn't get the job, because you need a much broader skill set than that.

I believe that for architectural rendering this is not the case. You're producing a few stills for the client so the render time per image is less critical.

I only know feature FX work because that's what I do, so maybe some architecural wizards could share their thoughts to broaden the topic?

Hope that's helpful, and good luck.

Andrew

rendermaniac
11-25-2003, 03:56 PM
Rudy raytracing isn't really that common (in film production at least).

Simon

gmask
11-25-2003, 04:01 PM
It's out as in for out of doors... :scream:

I dunno.. people still use lens flares so I imagine GI will be with us for awhile until it is replaced by something with a little more XDUGEF :cool:

Seriously as stated.. it's a particular look and a technique.. but it is not the end all be all.. a good lighter can work magic with the basic tools that most renderers provide

Dave Black
11-25-2003, 06:26 PM
I really think that people have latched on to GI as an overall lighting solution. It's simply not. GI provides only the fill component of light. If used as that, it can make or break a scene. I say use it, but do so only as it was intended. It's not the one button wonder many seem to think it is.

-3DZ

fxjeane
11-26-2003, 01:54 AM
Originally posted by rendermaniac
Rudy raytracing isn't really that common (in film production at least).

Simon


I dont know Simon. I have read and talked to alot of people who are using raytracing from MentalRay and some companies like Blue Sky and PDI use a good deal of it.
I believe the main reason its not to common is because PRman didnt raytrace until version 11, but know that it does im sure you will see more raytracing being used.

I think we have reched a point where raytracing algorithms are good enough and computers are fast enought that its cheaper to let a machine process a reflection that having an expensive TD setup and pre-render reflection maps....

once again maybe not. Thats just my opinion

Cheers to you all!

Rudy

Anteru
11-26-2003, 07:55 AM
You should also consider the time it takes to tweak all kinds of GI / RT calculation. If you do GI, you just click on the GI button and you hope everything will go right... TD like the possibility to tweak everything - a little bit of light in this edge, another spec highlight here etc. This can be a quite time consuming pass when GI is involved. And for things like reflections this is even more complicated. You can easily modify a reflection map per frame - it's not so easy to write a shader which does the same while ray-tracing.

Just my .02 $ though...

playmesumch00ns
11-26-2003, 08:35 AM
Originally posted by 3DZealot
I really think that people have latched on to GI as an overall lighting solution. It's simply not. GI provides only the fill component of light. If used as that, it can make or break a scene. I say use it, but do so only as it was intended. It's not the one button wonder many seem to think it is.

-3DZ

HDR IBL provides all components of lighting: ambient, diffuse, specular and reflection.

rendermaniac
11-26-2003, 02:23 PM
Rudy

If you have a few objects reflecting across several objects then it probably is far easier to just raytrace the reflections. Also if you have objects which aren't basically planes or spheres then setting up maps can be a pain.

However if you have a flat surface then it is often quicker to set up a reflection map. Using reflection occlusion can add a lot as well.

Most raytracing at the moment is done as a seperate pass, baked into the geometry, and then the baked data is used in the final render. It's very rare that you would use raytracing in the final render (but not completely unknown).

Image based lighting is very nice stuff, but real GI it aint. Frankly though it's usually enough and you tend not to notice most light spilling onto other objects - and if it is really obvious then you can most likely cheat it pretty easily.

There is also very little point using ray traced shadows - especially when deep shadow maps are available.

There's been some nice things done with using shadow maps to "bake" ray tracing. I am not sure if this is a huge benefit compared to the huge amount of setup necessary. Maybe for a lead CG character (Hulk, Dobby, Gollum etc which is where it has been done).

If you have lots of small objects though
the setup gets hairy and this is the point where I would consider just raytracing it and let the renderfarm deal with it. (although they have to be pretty small and not hundreds of em!)

I don't deny it has it's uses though - especially for complex refraction. Plus if you absolutely must have more than one bounce then raytracing is the only option. (eg. a room made of facetted diamonds reflecting your chrome CG character or something equally painful).

Simon

silv
11-26-2003, 02:59 PM
Originally posted by gmask
It's out as in for out of doors... :scream:

I dunno.. people still use lens flares so I imagine GI will be with us for awhile until it is replaced by something with a little more XDUGEF :cool:

Seriously as stated.. it's a particular look and a technique.. but it is not the end all be all.. a good lighter can work magic with the basic tools that most renderers provide

i don't agree. lens flares are an anomaly and happens rarely. gi is what happens ALL the time

gmask
11-26-2003, 04:30 PM
Originally posted by silv
i don't agree. lens flares are an anomaly and happens rarely. gi is what happens ALL the time

Lens flares happen anytime you point a lens at a bright light source.. I wouldn't call it rare..

What I meant is how the effect of GI is rendered will change. Currently Radiosity is a very popular method and then there is also FG etc.. there are like to be more accurate methods for this in the future or at least better algorithms.

Incitatus
11-27-2003, 12:06 AM
People tend to think GI is this 'one click' lighting solution sent by god or something, the end to all lighting problems.
This is imo a bit silly. Skilled lighting people will always be needed.

By their logic film or photography studios would just take a camera and roll/snap away, we all know that's not how it happens.

Lighting is an integral part of any visual art and it will always be that way. In fact I would go so far as to say skilled lighting the most important part of any visual art, it changes mood/color/perception everything.

GI is just a tool and quite francly a minor tool at that, it's just become such a big deal because it allows lesser skilled people easier acces to good looking work (myself included). But as soon as you look slightly deeper into the art of lighting it's a whole nother ballgame.

:wavey:

Vushvush
12-04-2003, 03:59 PM
To peraphrase Incitatus, if GI was the single component required, all film lighters should start looking for a job before directors realize they can film their movies by going outdoors on an overcast day!

Seriously though, it is ironic that in film, filming outside on an overcast day is ALSO the ideal situation. But the thing about that is, the reason filmmakers like overcast days isn't because it creates nice realistic detailed shading, but rather, because it frees them to light the scene the way THEY want.

Basically, GI/FG/AO/Radiosity, whatever, is the base, like your material's color. Now you have to give it character by building a 100 node shading network.

Go light!

3DDave
12-04-2003, 11:32 PM
I think Rendermans "Deep Shadows" is a significant step towards rendering without the need for GI.

playmesumch00ns
12-05-2003, 08:30 AM
How do you work that out? Deep shadows are great for rendering fur, grass, etc but they don't do much for a sphere. Plus they take aaaaages.

3DDave
12-05-2003, 10:37 PM
Granted, Deepshadows appear to add more control with how shadows fall and look. It's not a GI replacement, just a way to better control the shadows. You will still need to light the scene.

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