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Take A Break From Gi

46 posts in this topic

like sjmcc said this thread has gone off the course it was created for.

it wasnt about how good or bad Gi is or how much it is used by big productions.

it was about people using it when they dont need to.

where they could have used standard lighting with less render time.

eg.. if someone is doing a cartoony animation there is no need to make it look realistic with Gi and have 5 min/frame renders.

if you can get the same cartoony look with standard lights and reduce your render time

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With all this talk of photons and "realistic" lighting calculations, correct me if i am wrong, but as far as i know AR3, Vray and Fr work from the premise that rays are shot from the camera and bounced off objects. Photons coming directly from lights are use more in mental ray and can be used as a gi calculation in vray but for some reason it is not used by many

I believe that a photon based calculation should in theory be better for gi animation in camera flys as as far as i can tell since it is based on the lights theselves the calculation need only be done once for the entire animation ( if lights and objects are static), this should give something akin to a baked photon map which would stay the same frame for frame. Again i may be wrong and am going to look into vray photon mapping some more

Saying that i think max default radiosity engine ( note we used to call our gi radiosity) works on the idea of baking the calculation to meshses so again i think this is geared for camera flys

Edited by paulselhi

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Anyone talking about how GI is more realistic etc. might like to watch what professional photographers do for lighting setups in the real world.

They use every trick in the books to overcome the limitations and rules set by nature.

To me there is no debate GI vs traditional lighting. GI is only one more tool in the box of tricks and gimmicks you can use to achieve the look you want.

GI makes some effects that otherwise would need an advanced light setup comparably easy, but it offers less control than traditional lighting and is often slower. It's up to the artist to choose the tool for the job and at best this decision should not be based on fundamentaly biased views on what the "correct" tool is.

Correct is what works and gets the job done.

Cheers

Bjorn

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GI is only one more tool in the box of tricks and gimmicks you can use to achieve the look you want.

Cheers

Bjorn

Interesting choice of words Srek rolleyes.gif

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srek

Why does using GI "offer less control than traditional lighting"?

Cheers

Karl

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For example the shadows in a non GI setup are a good deal easier to handle in post work. The influence of single lights is also easier to modify in post with non GI setups.

Cheers

Bjorn

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Are you talking about HDRI lighting?

Cheers

Karl

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No GI No AO just lights, not perfect but renders in about 1.5 min a frame (AMD X2 2.4 Ghz) with glossy reflections done in post. i used area lights with softshadows (cachable) so an animation would be fast and net renderable.

With a big boy's computer you could go with area shadows and glossy in situ

post-161-1238684508_thumb.jpg

Edited by paulselhi

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Here is an image made with GI. Took about 5 min. to make from start to finish and has one light. If I tried to make this same thing with multiple lights the set up time would have been higher with the same results probably being impossible. Computer time is worth more to me then people time to a point. 100 hours or 1 person hour I would go with the person hour. Still, the right settings make GI rendering time acceptable to me. This scene also keeps looking good in an animation where having individual lights would make it harder to keep looking good. It comes down to what kind of look you want.

C4D R11 AR is amazing.

comp specs

1.7Ghz dual core amd

Note the blue wall reflecting onto the white ground.

Edited by Fastbee

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I think color bleeding is often over done in many renders, in the real world it is usually very subtle, put a red snooker ball on a white card and have a look for the bleed..what you don't have a snooker table ?? !! and more often than not the bleed is in fact blurry reflection which can be accomplished without GI

Edited by paulselhi

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I have been reading this thread and must admit to being totally confused about the debate.

Maybe I am wrong but there appear to be two distinct debates going on here:

1) GI vs Raytracing

2) Standard lights Vs HDRI lighting

AFIK GI can be used with either standard lights or HDRI lighting. As can Raytracing. You can also use lights plus HDRI and most renderers still use some raytracing anyway depending on which bit of the scene or type of object is being rendered.

Can't understand the "Standard Lights V GI" bit though. GI itself doesn't light anything.

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Did someone say "lighting challenge"?!

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Steve, I think you've hit the nail firmly on the head.

Cheers

Karl

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I dunno, what's the big deal either.

I love Gi coz it generally cuts set up time by like 10x. That means that you can send it off to render really quickly, and start working on your next project or watever.

Also someone mentioned using a the mograph skylight thingy. which produces great results. but it is most definately not faster than Gi. atleast not vray Gi.

I personally rarely go for realism, but i still love what Gi does. I honestly don't see myself doing anything except maybe technical or 2d style animations without gi.

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Achievements

ScottA.. my initial post was meant to make people think about whether they really needed GI in a render and to suggest that people investigate lighting setups more. I never said that GI was to be totally avoided, i never said to ignore GI

You seem to have it in your head that I am some sort of GI Luddite and you are a defender of innovation. You seem to have taken on the idea that I stand against GI and it is your sacred role to defend it.

Lets get it clear, i am not aginast Gi, i use GI, I have made tutorials about GI. A good GI render has me really bashing the bishop.

But I will stick to my original point that there are many times when GI is not needed and a good light setup MAY end up being a lot more predictable, stable and better for such things as object animation and net renders.

My intention was to state that with all this desire for "one click" GI solutions to scene lighting many people are ignoring the development of their lighting skills.

Personnaly i don't really care to much how you light your scenes, what ever floats your boat.

Edited by paulselhi

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i think if people are learning a 3d app then they should work on the lighting skills (with lights) before they move on to Gi.

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Looking at many scenes that people have issues with i often think..does this really need gi? Why is it that we have become so obsessed with doing every render with gi and often overlook the critical role lighting plays in a render.

i think if people are learning a 3d app then they should work on the lighting skills (with lights) before they move on to Gi.

And it's not our place to try and force him to change his mind.

Paul's premiss is absolutely right, people are splashing GI all over the place and often quite unessesarily. Here is an example that perfectly illustrates Paul's point...

http://www.c4dcafe.com/ipb/index.php?showt...=42573&st=0

As data says, people should learn to light, not just reach for the perceived magic bullet of GI. In fact, a lot of people simply need to learn what Gi actually is for starters. The general misconception is illustrated in post #24 in the above thread and the reality is touched upon in Steve's comment above in this thread.

I'm a big fan of GI renders, but there's a time and a place. And it's rarely a substitute for putting a good lighting setup in place.

And no-one is trying to force Paul to change his mind. Why would we, he's right...

Cheers

Karl

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If you look at the image i posted above then interior lighting is not always that difficult. I have only 8 lights here, 4 on the right acting as windows, one behind the camera and to the left acting as fill, two placed near the ceilings in each room acting as global fill and one on the floor pointing up being the floor light

for exteriors most people use 1 bounce in gi so a lighting setup that emulates that is fairly simple. A sun light and a dome hemisphere light and perhaps a floor/ground light simulating the bounced light from the ground the new sky automates that and that is why if you use it for an interior scene you will get a blue ambient look, this is due to sky dome light option in the details tab

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Is the one you've used on the floor one big Area Light?

Cheers

Karl

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yup, maybe should have made 2..not sure

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you just have to recreate what Gi would do.

simulate the bouncing light of Gi.

so you have to figure out what would be the strength of the light that would bounce off a surface.

then create a light that matches and pointing the direction the light would bounce

i read in the past about the ice age movie that Pixar made and it said they use over 30 lights in 1 scene.

so dont be worried about how many lights you have

Edited by dataflow

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