How to move "Indirect Lighting Cache" w/ a moving Level?

Development World Creation
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1

Dear UE4 Experts,

I have a large vehicle as a Moving Level using Static Lighting with Characters on board. I have added Character Indirect volumes and tuned the scale. The Characters look great inside the vehicle - however, when the vehicle moves the Character Indirect Lighting Cache stays put in world space and the Lighting Cache fails to light them as they move away from the Lighting data.

My question is: How do I move the LightingCache with the moving level?

thank you -

  dddavetv
2

Hi dddavetv,

Any lighting that is baked, which includes the Indirect Lighting Cache with that, is only static and cannot be moved.

If you wanted to keep the Indirect Light Cache for your ship you would instead move the worlds objects rather than the ship in the scene to accomodate this.

Thank you!

Tim

3

Thanks Tim,

If we were to keep the Vehicle stationary and move the World there would be other Lighting Cache problems with other actors.

It would seem logical if you can bake the Lightmaps and transform the Level and Lightmaps that the LightingCache should transform with the Level.

Can this be considered a bug?

This has to be a serious issue for many projects.

thanks again -

4

If you’re intending on using static lighting for other parts of your level then you would not want the world to move about your ship. Indirect Lighting doesn’t really work well for air or space type games as it is since the ILC will only place a sample above surfaces. It will not place them with in a large area that doesn’t have a surface to generate the sample from.

This cannot be considered a bug since it’s the way the system was designed to be static only. This system is effecient because it’s all handled offline so that it doesn’t have to be calculated dynamically. Ideally, Dynamic GI would be a solution here, but the two dynamic GI methods included with the engine (Distance Field GI and Light Propagation Volumes) are considered experimental.

You can fake indirect lighting by placing a bunch of low intensity dynamic lights that do not cast shadows and have a small radius.The game Into the Stars uses a similar method to fake bounce light to light their bridge on their ship. Dynamic lights that do not cast shadows are more efficient than baked lighting, while not as accurate, you can use them to get the effect you’re looking for.

Here’s an example shot from the bridge of the ship from Into the Stars comparing all the lights vs the final shot.