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Why is my level warning me that I don't have an Importance Volume?

hey guys, For some reason i become this error message after building light... can someone tell me please what this is about?


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asked Apr 20 '14 at 11:11 PM in Using UE4

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You need to put a Lightmass Importance Volume into your scene that encapsulates the area you want to build the lights for.

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answered Apr 20 '14 at 11:14 PM

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avatar image A-J-K Apr 20 '14 at 11:26 PM

Thanx! Where is this Lightmass Importnace ? Is it a option or what excatly? Where i can find it ? UE4 never asked before for something like this....

avatar image fighter5347 Apr 20 '14 at 11:29 PM

Just go to volumes and then drag it into your level + scale it up or down ;)

avatar image A-J-K Apr 20 '14 at 11:33 PM

Thanx, i found it... can you maybe tell me what the use of this Lightmass Importance is? I guess it has something to do with the lightmass :) but what excatly, in my last scenes UE4 never asked for a Lightmass Importance...

avatar image fighter5347 Apr 20 '14 at 11:35 PM

"Lightmass Importance Volumes are used to focus Lightmass calculations. Lightmass is the precalculated lighting and global illumination system used in Unreal Engine 4. In order to minimize - and thereby optimize - the amount of processing needed to generate precalculated lights in a level, Lightmass Importance Volumes are use to enclose the areas of the level geometry. Lightmass will only calculate within that area, skipping anything outside of it.

For more information on Lightmass and Lightmass Importance Volumes, please see the Lightmass documentation."


avatar image Jacky Apr 20 '14 at 11:35 PM

Basically it limits the area lightmass calculates so that you dont spend hours trying to build lights for infinity. It is needed only when you build lights for static lighting.

avatar image A-J-K Apr 20 '14 at 11:42 PM

Ok got it, thanx! But i'm still curious why UE4 didn't asked for a lightmass importance in my few last scenes...

avatar image fighter5347 Apr 20 '14 at 11:54 PM

I think because now you have used a big landscape -> just in a big level with many meshes you need a lightmass importance volume .

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