GLOBAL ILLUMINATION DISCUSSION

[Zytrex]

Huh.... *ponders*

[kapil]

Hi all, yes about lighting i have seen some of the works of a russian artist i think u all must have seen his work too. I m talking about savinoff, must say he is a genius in his style of lighting, though most of his lighting seems similar.
Another artist who is called now a days michelangelo of 3D and had been interviwed by 3D total. u must all know about him too. I have nothing to add in your arguments. wish u all illumination

[Zytrex]

Thanks for the reply, kapil, and welcome to Threedy.

[Cinematography]

"Am I the only person getting fed up with GI because of how difficult it can be to get even barely acceptable results without ending up with horrible rendering times?

NO. I'm also trying to work out some GI problems. Right now I have my rendering time down to about 13 minutes per frame.

I’m using about 20,000 photons at an intensity of 150,000 [big area]. My Global Illumination accuracy is set at 500, and my Final Gather accuracy is set at 200. There is still flickering in my rendered animations, and I will probably correct this problem by increasing my photon count to 50,000, and my Global Illumination accuracy to about 1,000.

These settings are not universal though, as I learned from moderator @ the XSIBase. [I’m using Softimage|XSI] You must go through a kind of trail and error process to see which settings will work best for your scene, and do a few test-renders to check for artifacts and flickering.


There are little things that happen when you render with GI that you can't get when you render without GI. For example, if you have a character moving through a space that is made up of different colors set at different brightness values, you can see the reflected light change against the character. This could probably be done without GI, however - you can create a much more accurate and realistic result if you use GI.

If you want to render out an animation using GI, I highly recommend that you don't render out every single frame. You would probably be better off rendering every other frame, and then taking the animation sequence into an editing program and slowing the playback speed by 50%. It may still take you about 30 minutes to render out every frame, but it won't take as long to render out the entire animation.

[LCGuy]

Interesting thread.

I believe that the purpose of creating a 3D scene is to produce a final rendering that looks as it is intended by the artist. Sometimes, that is photo-realistic, and, sometimes, it's not.

No matter what the final goal is, it is ALWAYS the ultimate goal of the artist to get there as quickly as he/she can. So, given that, one must ask the question:

"What parts of the whole process are the most time consuming?".

Well, for simple scenes, setting up light arrays can be quite time consuming. Or, setting up 10 or 15 (or more) strategically placed lights. Add a little more intensity here, give that one a bit more bluish hue, etc... test render it, nope, that won't work, move it a little to the left, etc...

If the point is to spend time duplicating the real world "diffuse light" condition that radiosity comes quite close to yielding, then, perhaps it's time to explore other ways to reproduce it.

I personally favor using a glowdome; the scene placed inside the top half of a hemisphere, which has a "glow" texture (shader) applied to it. It's quite efficient, because, it keeps all of that valuable diffused light bouncing around inside of it, where it is most useful. And that makes having to adjust it less important, which, saves time.

At times, I will add a spotlight or two to accent something, as well; there's no sin in that, just as long as the amount of time that I spend futzing with it doesn't begin to become a project itself, then the technique is still practically logical to use.

There are, by the way, some variations to this, as well. One can map a small white gradient circle inside a black field onto the sphere, and use that to be the "sun" light forthis same application, and aim it, by rotating the sphere accordingly inthe modeling window. This yields the same advantages of a typical glowdome, with the added ability of focusing the light's concentration on one target area, just like a regular light object, but, with the added convenience of that wonderful softness that diffused light gives off, due to the converging lights frome its spherical shape; its a thing of beauty, actually.

I use Strata 3D Pro, which is has a very powerful radiosity renderer, and both the above can take a fairly long time for complex scenes. I have had to wait for as much as 48 hours for some, and as little as 12 minutes for others; it all depends on what my ultimate goals are, however...

I can tell you that my total project time is reduced because I'm NOT setting up and constantly testing/retesting and futzing with dozens of lights, and the results are what I intend them to be.

Remember, while the computer is rendering, you are free to do other things;

My $.02.

Great thread.

[sneaky_d]

That's a good tip LCGuy - like that one...

sneaky_d

[Zytrex]

The problem with solutions like that (glow domes, light lattices, e-light script, etc.) is that they are for outdoor scenes. Let's talk about some diffuse light solutions for indoor scenes.

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Well, start talking. I don't know any.

[ag79]

hey guys

i have been using gi for a while. i think it gives good results & faster ones especially when u r workin on a deadline and don't have too much time left for creating an impressive light set up.
as for the question of rendering animations with gi, max 5 gives a tool to render-to-texture. this means calculate gi once then switch of gi for rendering rest of the animaton. i don't know if this sort of thing is there for other renderers like brazil & vray.

cheers

[Bullseyepimp]

Hey guys, I think I'll join in on this discussion.

I do have to agree that GI is the easy shortcut to realism, but its rendertimes are rediculous. I do think that the "Shadow Map" feature in max is really underrated and not used enough. It is the most powerful shadowing tool that comes with max if you know how to use it. Shadow map also has the fastest render times out of all the shadowing/lighting tools that come with max.

Theres what I think

[Zytrex]

I'll agree that shadow map is faster and its very design lends itself to creating softer, more natural looking shadows without using any kind of area light or area shadow calculations. There are some problems though, last time I checked. In some complicated scenes with very find detail creating by actual polygons, not just textures, shadow map can cause some problems, especially with getting the shadow to properly line up with the object caster. Also--again, last time I checked--it cannot create partial shadows through translucent textures/objects.

[Psistorm]

as I first got my hands on the Brazil test, I was quite happy with the skylight feature, and thought it made stuff look great
now, when I got my hands on fr stage-1, I still use skylight for car renders (but with a HDRI map mostly) or preview renders.
but I actually start to think about sunlight, fill lights etc.
I go for a general light direction and then add one or two lights to tweak things a little.
GI being made available to everyone is quite a great thing, and imho it still takes a lot of skill to make the scene look truly awesome.
skylight might be enough to impress normal ppl, but anyone who spent some more time studying light setups can judge a good from a bad setup

[DeathGoth]

I have a few examples of a room that myself and a reind was working on.. refering to GI and non GI... I think the room is good.. I use vray to take care of GI inside a room.. considering I use only one sunlight.. and a lit image for a bluish tint.. but i will show the images.. for 1 it is faster than setting up 3 million lights to do what you can wit 1 light.. I think trying to make a non GI scene as GI is a waste of time cause there can be other things you can do to the scene than mess with this light.. GI is made to make out lives easier.. not to debate whater it sucks or not... anyway here are the images...


This is the sorta final on the room...


This scene is just a image being lit only.. there is 1 light in here but its off..


This scene few textures.. sun added.. There is just that one light in this scene and the blue image showing the sky..


This is no GI.. 1 light.. backlit image for sky..


This is 2 lights.. no GI and backlit sky..



This image is just a mess aground.. since my comp got erased cause of windows.. this file comes from a recover.. but i did this to show the GI part of this scene.. see how the yellow is covering just about everything in diffrent amounts....

anyway that is my thoughts on GI vs non GI... but I have been told I should learn traditional ways to light a scene other than GI.. cause most people in the work place dont use vray, brazil, final render... so you should keep that part in mind also...

[mehran khan]

I n my opininon simulating true giwith light tracer is preety harder,
and does not always gives a true result. it does not allow all that bouncing of light.(you know a white t-shirt against a red wall does not get a red shade to it) well not atleas to me.
And that elight script, It's nice but than again on my lame machine it runs twice slower than light racer. And if you try placing a raytraced floor in an open enviorrnment and than use
e-light You get this.

[mehran khan]

oops forgot the image.
It looks like as if the geometry is placed on a disco floor.
Loks noice to me but not what I wanted

[mehran khan]

I am just a newbie, I spent last year trying to learrn modelling,
Now for the past few weeks I have been wirking with mental ray on how to set up a good light.
Which brings us to my next point. Rendering animations in max6 with gi can be a time consuming task, but if you save the photon map and uncheck the rebuild option in the renderer tab in render ialogue it will save you a lot of time.
Please notify if this is wrong