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DFGI No effect, Height fields and dfao working

So I posted this on the forums initially, but I'm posting here due to the relative lack of interest there as well as my realization it may not have been the best location to post.

I need to get DFGI working in a project I'm doing, and I understand it's limitations... I'm not doing anything speial that should be breaking it, but instead this seems to be related to user error.

Essentially, enabling DFGI via console variables does absolutely nothing (except for terrain heightfield GI which works fine).

DFGI Alone fails to work properly, and emissive lights have no effect (though, I was made to understand emissive lighting is not a feature compatible with DFGI which is fine). The directional light produces strange and improperly distributed spots of light near the general area of the light bounce, but they are obviously not he intended result.

Here's an image of the strange behavior (which I assumed was linked to LightPropagationVolume settings, but post process volume LPV settings had no effect {enabled and unlocked the volume}). alt text

DFAO works fine as do distance fields (enabled and visualize properly), but DFGI does not seem to be occurring. I should also note, the same occurred to a fresh test scene from a newly installed 4.14.0 version, and I got the exact same results (an obvious pointer to user error), so, in order to perhaps simplify the process, could someone provide step-by-step instructions for getting basic DFGI results from scratch, just in a test scene. That'd be great!

I should also note, the spotty points of light on the wall bled through meshes, which is supposedly not characteristic at all of DFGI, but rather of LPV. Furthermore, their intensity is affected by indirect lighting strength not of the skylight but of the directional light.

I should also note, I have set them to movable, and made sure I followed the step-by-step process outlined in several forums, so this is especially strange (ESPECIALLY with the 4.14.0 tes scene, as this clearly points to user error, and I'm pretty sure I did everything correctly).

ANY and ALL help is welcomed and readily appreciated.

Thank you!

Also, I can provide more information if required. On another note, saving a project with DFGI, at least in 4.13.2, was the cause of a strange crash. Disabling DFGI fixed it. Not sure if this is related, but I can certainly reproduce the bug if anybody wants to mess with the project file. On one FINAL note, I am on a relatively limited time-plan, and need to have a project (hopefully and almost necessarily involving DFGI) done in 2.5 weeks, so a general sense of urgency is always appreciated

Thanks again!.

Product Version: UE 4.13
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asked Nov 16 '16 at 11:05 PM in Rendering

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Skunkmeister
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avatar image Skunkmeister Nov 17 '16 at 11:09 AM

This seems relatively simple... anybody with any DFGI experience, please feel free to comment! Even just saying what you've done in the past and a vague idea as to how with DFGI would be great!

avatar image Skunkmeister Nov 17 '16 at 10:47 PM

T-14:06:12:48

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Hi,

My page here for how to use DFGI should help you, but with that being said, there are likely some things that have changed since I posted that tutorial: http://timhobsonue4.snappages.com/distance-field-global-illumination

Now with that being said let me cover some of the other things you've brought up.

I need to get DFGI working in a project I'm doing, and I understand it's limitations... I'm not doing anything speial that should be breaking it, but instead this seems to be related to user error. Essentially, enabling DFGI via console variables does absolutely nothing (except for terrain heightfield GI which works fine).

DFGI has been abandoned for some time (Since 4.9-4.10 I think). It's something that may be picked back up in the future, but it's currently on indefinite hold. I wouldn't recommend using it beyond just landscape usage, and even then you may run into issues with performance or performance regressions since it was put on hold. Static Mesh GI isn't near anything ready for production use. If anyone is using DFGI it's best to disable it for static meshes and only use it for your landscape.


The directional light produces strange and improperly distributed spots of light near the general area of the light bounce, but they are obviously not he intended result.

This was the state it was left in when it was put on hold. If you use DFGI disable it for static meshes by using r.VPLMeshGlobalIllumination 0. This will only use DFGI for the landscapes heightfield.


I know this probably wasn't what you wanted to hear, but out of the dynamic GI options that are currently available, it would be best to use something like LPV over DFGI for the best results and experience, especially if you're on a limited timeframe.

-Tim

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answered Nov 21 '16 at 03:58 PM

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Tim Hobson ♦♦ STAFF
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avatar image Skunkmeister Nov 29 '16 at 11:14 PM

No it's fine! Thank you so much for your response!!! I finished my project long before the timeframe was over at a great quality, as I realized there was absolutely no reason not to use static lighting (literally not one).

Your timely response is incredibly appreciated!

I genuinely look forward to seeing more dynamic global illumination solutions implemented or improved, but of course, I am exceedingly thankful for that which Unreal engine comes with now...

Thanks again!

I do however have another question: In the instance that I do want to use LPV, what are the necessary steps to get it working properly?

LPV settings changed nothing on a postprocess volume having followed instructions in some other threads, so perhaps you could provide some clarification in regard to the steps of setting up LPV?

Thanks again!

avatar image Tim Hobson ♦♦ STAFF Nov 30 '16 at 02:28 PM

In the instance that I do want to use LPV, what are the necessary steps to get it working properly?

https://docs.unrealengine.com/latest/INT/Engine/Rendering/LightingAndShadows/LightPropagationVolumes/

Just make sure to add r.LightPropagationVolume=1 to your consolevariables.ini file and then launch the editor. Then add a Post Process Volume and set it to unbound. Then you can increase the LPV intensity and various other options in the Post Process Volume Settings.

That's pretty much it. LPVs work well for open environments in outdoors where a lot of light leaking won't be a big problem like you would get with interiors. This feature was developed by Lionhead Studios for Fable: Legends before they closed down. It looked really good in their environments which used a lot of foliage and outdoor areas.

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Thank you so much Tim!

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answered Dec 02 '16 at 12:19 AM

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Skunkmeister
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