Global Illumination

So I noticed this global illumination setting in the game's graphics options.

But for those of us who ever built anything underground, inside buildings or simply tried to do creative night lighting in the game, we can say that game clearly does not do what the rest of the world calls global illumination.
So what does the setting do exactly ?

Let's try it out. This a a pretty simple test scene designed to highlight global illumination.
We direct some light on large coloured surfaces and see how the bounced lighting affects our models
globalillumination_1.jpg


We can see a tiny bit of red being reflected here, but only on the closest part of the model and only the surfaces almost parallel with the wall receive enough red lighting to make the effect visible. The rest of the scene does not benefit from the reflected light.
Yes, this part of the statue is right at the limit between light and shadow, the wall is 2m from the hand, the wall is exposed to the brightest light in the game (sunlight) and that's all you get ??!?
From the rear of the box, it looks like our concrete wall is translucent. That was not expected.
globalillumination_3.jpg
globalillumination_2.jpg


Let's rotate the scene and have the sun illuminate the other wall.
It looks like the princess' model model is not receiving any blue light.
globalillumination_4.jpg


At night, we can see that moonlight in the Planet Coaster universe is also capable of piercing through concrete. (blue hue going through the entire white rear wall)
globalillumination_5.jpg


Unfortunately, there is no effect beyond the extremely weak moonshine, the spotlights do not affect our models at all.
globalillumination_6.jpg


I don't know what to do with this "feature".
Is it a bug or did frontier just try, failed to implement global illumination and just forget to remove it from the current build ? Because apart from rendering your buildings translucent to sun light, the current global illumination setting is pretty much useless.
 
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Yay, Science!

That said, I'm not understanding what you're testing here. Did you tweak the global illumination settings to see if that made any difference, or is this just the baseline control with the default settings?
 
I just noticed the setting in the options and turned it on.

Global illumination means that any surface of a scene can emit light. It allows a scene to be lit by indirect light.
1. The sun illuminates the red wall
2. The red light from the wall bounces and illuminates the scene from the back

It is an advanced type of lighting that usually requires very lengthy calculations. It used to be only used for static lights baked in the geometry.
But more recently, more and more game engines have started implementing this type of lighting in real time thanks to the huge processing power of modern graphics cards. (and I guess they use special shortcuts in their algorithms to make it much faster than the old ways)

Example (unreal engine)
[video=youtube;yoovPHemuK4]https://www.youtube.com/watch?v=yoovPHemuK4[/video]
 
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Note that we can place as many lights as we want. If every light caused global illuminiation it would probably kill the fps.
 
My Rapids travel through a plain (terrain) tunnel, it is not decorated and I have yet to add lights; Therefore it is quite dark even during daytime. When following the boats with the ride cam, I noticed a strange green light just ahead of the boat. It fades out as soon as the boat comes closer, like some wrongly timed trigger effect. Needless to say I have no triggers setup, there are not even any light sources to trigger at all. The track of my ride happens to be green, so the source must be the light bouncing off the track...but there is no reason for that happening because it is supposedly pitch black underground. Could this be related to the bugged Global Illumination as well?
 
globalillumination_6.jpg


This^ does not seem right at all, shouldnt the statues be lit up and not dark??


as for the reflection of light, that seems like a very minor detail for a game like this doesnt it? I mean I understand why you brought it up, the option is there so why doesn't it do anything? Maybe the devs will "shed some light" on the situation [cool]
 
I am still missing some shadows that should be there.
I mean, I personally dont want to have 100 % accurate-calculation of these things (that would definitvly blow up all machines), but some little realistic should be implemented.

Only Globallight seems to throw shadows ans work correctly. Lightsources didnt.
 
This^ does not seem right at all, shouldnt the statues be lit up and not dark??

as for the reflection of light, that seems like a very minor detail for a game like this doesnt it? I mean I understand why you brought it up, the option is there so why doesn't it do anything? Maybe the devs will "shed some light" on the situation [cool]
This is a test scene designed specifically to try and see how global illumination is working.
I set up the spot lights to avoid lighting up the statues on purpose. Global illumination should be able to detect the wall are illuminated and bounce light back on the statues from behind. The screenshot shows that this isn't happening. There is only the primary lighting direct from the spotlights and no light coming back from the wall. The only thing illuminating the statues from the back is the moonshine going through the concrete wall.

The reason why I brought this up is because :
- Lighting is part of gameplay at night
- The game does not offer enough lighting options to do without global illumination (you need more than the few options currently in the game light up scenes properly without global illumination)
- There is a setting called global illumination in the game's graphics setting

The last 2 clearly show the intentions of the developers to use a realistic global illumination lighting strategy, and not the simplified classical lighting strategy.
Something went wrong during development and we have neither global illumination nor the variety of light types required to compensate.

This is why there is no way to produce dark interiors. This is why the underground lighting is so broken. This is why it is so bloody hard to light up buildings and streets at night (because you only have direct point and spot lights and no way to control ambient lighting)

Note that we can place as many lights as we want. If every light caused global illuminiation it would probably kill the fps.
Global illumination is not measured in number of light sources since absolutely EVERY polygon is a potential light source. Global illumination is usually implemented as a raytrace algorithm, and the duration of the algorithm depends on screen resolution, the number of bounces and the number of rays per bounce demanded by the programmer (aka how many times you you want the light to bounce and the precision of each bounce).
It can last from just a few seconds for a quick test render to multiple hours for a professional production render. Which is why in games it is usually pre-rendered and baked into geometry : this can only be done for fixed objects.
Implementing global illumination in real time requires the game developer to find clever tricks in order to simulate an approximation of global illumination using the toolbox of conventional real time lighting algorithms.
--> It requires inventing new algorithms and a lot of programming work.
 
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