How to import GI Lightmaps from external renderer (V-Ray)?

Hi Guys

From my other post :smiley:

As the title suggests, I would like to figure out what’s going to be easier for me to work with - calculating the GI in V-Ray (which I’m very accustomed to) and exporting it to UE4 or generating GI in UE4. I will note that I will likely only need static GI.

My only issue with lighting in UE4 at the moment is the absence of a plane light (please developers! :)) and after years of using V-Ray, the GI results are very predictable.

I know how to Unwrap my UVW’s and set them to channel 2 in 3ds Max, I also know how to render to texture in V-Ray. From there I know nothing :slight_smile:

Can anyone give me a step by step on how to import GI calculations from an external renderer to be used in UE4? Furthermore, assume I put in a couple of lights within UE4, would that completely ruin the GI I’ve imported from V-Ray?



There isn’t any way of doing that currently, the way the system works it doesn’t have any way of trying to do something like that easily. The main benefit of doing it with UE4 is that you can easily change and update things and don’t have to even think about the lightmaps when you build your lighting. I’ve used Vray with Unity and it was a pain because you have to assign the lightmaps to each object individually.
In the latest version of UE4 it does have long lights now, not quite as good as planar lights but it’s getting there, you can adjust the radius and the length to get that type of area lighting. And I hope in the future we will get things like a planar light or even emissive lights.

In UE4 the lighting is also more physically based–it’s in lumens instead of an arbitrary value like in UDK. It also supports IES lights so most things are going to be the same, it’s just the lack of things like a planar light.

Thanks mate.

A bit dissapointing. I’ve read about people rendering out GI and placing into the emissive slot, although that could be with UDK only. I’ll give it a shot to compare.

Looks like GI is going to have to be in UE4. I’m going to hassle the developers every month to put in a traditional plane light :smiley:

EDIT: I can’t actually find the long light? Must I download it seperately?

All lights have a source length value, it’s been there in all versions of UE4, but in version 4.4 when you build lightmass it will render the length like it’s actually a long light. You also have to change the source radius as well.

You can fake plane light for soft shadows for now with the technique used here:

GI is in Unreal 4 - at least a way to tweak the Engine to do it. I made a scene with it - it’s very stable, but I couldn’t get reflections to work and didn’t want to use custom made cubemaps (made with the Nvidia Texture Tool).

I would complain about the lack of import options for custom Lightmaps, only if I had any issues with the current lightmapper. But the current lightmapper is bloody brilliant, so start using it first, and complain when something can’t be done in UnrealED. Here is the link to GI in Unreal 4. Easy stuff:

why not render all of the lighting to the the texture map and make the objects self illuminating in unreal?

Because it won’t render correctly, and things like specular lighting won’t work, and you wouldn’t be able to integrate it with dynamic lighting.

should work well if you dont have any other lighting and mark the object as moveable?

If you don’t care about reflections or specular and it doesn’t have to interact with anything dynamic then it could work