Fake GI practice

[wuannone]

I am new to this forum but not to vray or 3dsmax. At the moment i'm diving in to faking gi. On my last project I had to render an animation of 2000 frames with GI and render it on an online render farm. The render costs were $1200,- it needed to be rendered in 2 days. Me and the client werent happy about that.

 

Tried some fake GI on an interior project. This was my result. Quite happy about it.

screenshot program

 

I want to have precise control over the render and get as close to the GI render as possible. I've done a test with a simple red sphere and a grey floor. This is the result.

how do you print screen

 

The problem I can't seem to fix yet is how to create color bleed in a shadow with an omni diffuse without making the shadow brighter. So I only want to give the shadow a red tint. I can't change the shadow color since that would change all the shadow colors.

 

It's quite a challenge to get it right. I've attached my scene with the sphere for you if you would like to give it a try and come with a better result.

 

ps: I've searched this forum and picked up great tips for fake gi.

FakeGIsimpleScene.zip

[Chris MacDonald]

If your client can't afford circa $1,200 rendering costs, can they afford an animation?

 

good results btw, but I can't even begin to imagine trying to fake GI on the size of scenes I work on - it's what we've spent years getting away from because it's so laborious and time consuming to set up.

[wuannone]

The client doesn't know anything about rendering. They just wanted a cool animation about a product. I only want to use it in projects with lot of frames to render on 4k for example. Saw great results on the internet in faking it. I read that even the big studios in hollywood don't even use GI or at least till a few years ago.

[Chris MacDonald]

To light a scene (well) without GI for me would cost way more in terms of my hours than being charged for render time, so it's just a non starter really and leaves me to spend time on more important aspects.

[RyderSK]

I kind of doubt a fake GI can save anything at all these days. Precomputed IR/LC is almost free regarding the time. Sampling the remaining noise (direct light, specular effects, DOF/Motion blur) is what actually takes the time.

 

Without GI you could have just sent it to Unreal 4.

[wuannone]

"Precomputed IR/LC is almost free regarding the time."

What do you mean with this? If I have an animation of 2000 frames with a moving camera and moving objects I have to calculate the LC and the IR for about everyframe. First calculating the LC and then calculating the IR and then rendering it all. That gi calc can take up to 30% of the total render time I guess. Or am I doing something very stupidly wrong?

[Chris MacDonald]

I use Brute force for everything these days.

[wuannone]

I use Brute force for everything these days.

But BF is the slowest engine regarding noise solving. It's the easiest setup but also the slowest render.

[Chris MacDonald]

It really isn't that slow. What kind of frame times are you aiming for?

[Devin Johnston]

I have to agree with the others here, you might be getting faster render times by faking GI but how much time have you spent setting it up? Instead of trying to fake GI why don't you invest the time in learning how to optimize it, you can gain significant speed just by changing a few settings if you understand how they work in your scene. I'd also like to point out that $1,200 isn't expensive for an animation of that length.

[Francisco Penaloza]

Faking GI is an old craft, never the less still useful if you have too many moving objects and cameras and strange effects. But as mentioned by others it is very time consuming.

I had the opportunity to see a presentation from Jeremy Vickery, long time ago, it was mind blowing how much they work lighting in big scale productions, but also there is a lot done in post... most of the time more that what we think.

 

Any ways he also mentioned how useful was using GI because of time saving to recreate all that light bouncing and bleeding that otherwise you'll need to rig by your self. Yep light rigging. For instance in your scene sample you'll have to put a spot light for that sphere alone to tint the shadows the color you need. That light will affect that sphere alone, others light won't participate. Imagine doing that for each object in your scene. They used to do that only for the hero characters or foreground character, the rest was a simple lighting because other wise, it will take forever.

 

Yes GI has problems, is not perfect, but this past years has evolved so quickly that using brute force is not prohibitive any more. One of the reasons that Studios use Arnold, is because it can take care of GI very easily, no matter what, so the lighting setup becomes faster, material response is predictable, so are effect such motion blur and DOF, that saves a lot of time.

 

As a personal research I would encourage you to keep trying different methods and try to read from other artist, but with today's technology and hardware advance, it may not be the magic solution that you hope.

For example, you have Unwrella or Flat Iron, you could unwrap the whole scene and bake all maps and lights then render with not light whatsoever. if nothing move, this may be even faster. Shoot you could use in real time.

Of course if you have landscaping, people and such, this won't work, the loading time will be prohibitive.

[RyderSK]

Ah, I meant you just had fly-through. Yup, if stuff is moving in this days, BF/LC is the only choice. BF itself can't be optimized ( no, none of the tricks Grant had shown in Vray 2.4+ apply anymore in 3.4, NONE ) but you can clamp the crap out of everything. Set glass (and other mats with mirror reflection or refraction) to 4 bounces and every other specular material to 2. So the renderer is doing as little work as possible.

 

Go for cheapest light solution, huge area light/light portal instead of dome,etc..

 

But don't expect miracles. 3.4 is so self-optimizing that you will not get out of it significant changing. There are no secrets anymore, you set the desired visual quality and you get some time out of it. Just that.

 

And the last sad truth that Devin said, 1200/min. is even rather cheap for interiors : / If clients are ok with fake GI look, start learning real-time.

[wuannone]

Faking GI is an old craft, never the less still useful if you have too many moving objects and cameras and strange effects. But as mentioned by others it is very time consuming.

I had the opportunity to see a presentation from Jeremy Vickery, long time ago, it was mind blowing how much they work lighting in big scale productions, but also there is a lot done in post... most of the time more that what we think.

 

Any ways he also mentioned how useful was using GI because of time saving to recreate all that light bouncing and bleeding that otherwise you'll need to rig by your self. Yep light rigging. For instance in your scene sample you'll have to put a spot light for that sphere alone to tint the shadows the color you need. That light will affect that sphere alone, others light won't participate. Imagine doing that for each object in your scene. They used to do that only for the hero characters or foreground character, the rest was a simple lighting because other wise, it will take forever.

 

Yes GI has problems, is not perfect, but this past years has evolved so quickly that using brute force is not prohibitive any more. One of the reasons that Studios use Arnold, is because it can take care of GI very easily, no matter what, so the lighting setup becomes faster, material response is predictable, so are effect such motion blur and DOF, that saves a lot of time.

 

As a personal research I would encourage you to keep trying different methods and try to read from other artist, but with today's technology and hardware advance, it may not be the magic solution that you hope.

For example, you have Unwrella or Flat Iron, you could unwrap the whole scene and bake all maps and lights then render with not light whatsoever. if nothing move, this may be even faster. Shoot you could use in real time.

Of course if you have landscaping, people and such, this won't work, the loading time will be prohibitive.

 

Thanks everybody for the clear reactions. I've heard more people about baking the lights. However I think that is the least efficient way to work. If the client wants some objects on a different place or add some extra models to the scene you have to bake everything again. And for as far as I have experienced baking isn't really fast either.

 

Last few weeks I have been reading and reading about image sampling. Subdivs and noise treshold. Decreased subdivs of the image sampler to 12. Noise treshold to 0.06. Shading rate on 12. That's as far as I could improve the settings on that part. The IM is set to Medium-Animation. Light Cache to 1000subdivs. BF+LC seems to be the way to go then I guess. Did some tests and rendering the same shot with IR+LC was 2 times as fast as BF+LC. But way more time consuming to setup. Guess there is no other way then to deal with the long render times (14min per frame interior sci fi corridor on 4K resolution 360 camera).

[Francisco Penaloza]

Guess there is no other way then to deal with the long render times (14min per frame interior sci fi corridor on 4K resolution 360 camera).

 

really!!! you are complaining for 14 mins at 4K 360Degree frame?

 

Not sure where you live, but honestly, $1200 for 2000 frames it is about what we all pay. If you client do not understand that, it is because he does not know what he is talking about. If he is used to pay $200 per image, animation is a different beast. Even more if you are offering VR images.

Come on, Love yourself a little and explain your clients that high end technology has a price. it take time. We are not machines, we craft images. There are man hours behind this.

Take a good read tho this interview to Ernest.

If your clientele just want click button solution you are wasting your time studying light rigging and such, just get Lumion and forget about headaches

 

People nowadays are just spoiled.

Edited September 29, 2016 by fco3d

[wuannone]

really!!! you are complaining for 14 mins at 4K 360Degree frame?

 

Not sure where you live, but honestly, $1200 for 2000 frames it is about what we all pay. If you client do not understand that, it is because he does not know what he is talking about. If he is used to pay $200 per image, animation is a different beast. Even more if you are offering VR images.

Come one, Love yourself a little and explain your clients that high end technology has a price. it take time. We are not machines, we craft images. There are man hours behind this.

Take a good read tho this interview to Ernest.

If your clientele just want click button solution you are wasting your time studying light rigging and such, just get Lumion and forget about headaches

 

People nowadays are just spoiled.

 

thank you. very interesting article. You guys were right about the fact that it isn't the GI that takes that long but the other settings. It were the materials that were cousing the long render times.