The dynamic GI Myth
Running source built UE 4.6.1
I followed the following tutorials
1.https://wiki.unrealengine.com/Light_Propagation_Volumes_GI 2.https://docs.unrealengine.com/latest/INT/Engine/Rendering/LightingAndShadows/LightPropagationVolumes/index.html 3.https://forums.unrealengine.com/showthread.php?6914-Light-Propagation-Volume-now-works-with-Emissive-Material!!
And none of those enables any GI at all.
This is my ConsoleVariables.ini
In the directional light (moveable) I have "Dynamic Indirect Lighting" checked (There is no "Affect Dynamic Indirect Lighting " check box anywhere)
In the emissive material I have "Emissive (Dynamic Area Lights)" checked (There is no "Dynamic Area Lighting" check box anywhere)
I also turned off the light map in world settings and placed an unbound post processing volume.
And then when i hit build There is no GI at all, The shadows are still sharp pitch black and the emissive material does not emits a single ray of light just bloom (color multiplied by 30)
So has dynamic GI removed from 4.6.1 ?
asked Jan 31 '15 at 09:10 AM in Rendering
Hi Commander Shepard,
I can assure you that Dynamic GI is in fact not a myth currently. LPV has been in the engine for quite some time (Enabled via the console variable r.LightPropagationVolume=1, as you pointed out).
By default in the editor it is off. You'll need to adjust a couple of things to get it working correctly.
Make sure you Directional Light has "Dynamic Indirect Lighting" checked so that it can be injected into the LPV.)
To further adjust settings you'll need to place a Post Process Volume in your scene and make sure it covers any areas you want to have the LPV affect or set it to Unbound to affect everywhere no matter its size.
Here are the results in 4.6.1:
I start out with No LPV and then enabled it via my directional movable light. Further settings in the post process volume.
This is still a non-production-ready system. There are known issues with it and it is expected to be buggy and experimental. Light leaking between exterior and interior scene is very noticeable.
With that in mind, there is also another method of Dynamic GI that is being explored currently as well. This is using the Distance Fields to generate GI and this feature is being actively developed.
You can find more information about it in this forum thread: https://forums.unrealengine.com/showthread.php?2421-Global-Illumination-alternatives&p=193884&viewfull=1#post193884
The engineer behind Distance Fields has also said this in that thread as well:
Compared to LPV here's how I see Distance Field GI: + Vastly higher quality indirect shadowing - leaking is actually solvable + More detail in color bleeding - material is evaluated per surfel (disk) isntead of for a huge voxel + Much higher view distance, not limited by volume texture scaling + Only single bounce for now (can be improved) + Have to be able to represent your scene with distance fields / heightfields
Take a look at the screen shots in this thread as well.
I hope the myth here has been busted and it actually does work and exists. :)
Feel free to ask any questions. If you need help giving the distance field method a shot I can help there as well.
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