Full dynamic lights vs mixed Static lights performances

[Talad]

Hi guys, I have a question on large worlds. We have one big light (sun light) which is not moving as we do don’t need this light to be moving in our game. then we have a number of other dynamic lights.

We have set SkyLight as Moveable and DirectionalLight set as Stationary. Other combinations seems to crash lightmass on some of our levels, so we avoided those (example both skylight and directional light as static).

With this setup on large levels the static build data is quite big, example one level has 744Mb of Build data file. I know that static light should have better performances than full dynamic lights, and this is why we use it, but at the same time I’m wondering if such large datafiles are going to be detrimental on the other side on memory and loading times, and so at the end affecting performances anyway. Are there guidelines/best practices on this?

[ClockworkOcean]

It’s a trade off. Static light is more efficent, to a point, but does use a lot of memory. Dynamic lights take more resources at run time, but less memory.

There is no best practice, you have to do what works best.

I know a lot of people use dynamic lighting for large worlds.

[OzMomotaro]

I’m not sure why you would have ‘skylight’ as moveable… as this is often (?) used for indirect lighting (ie the lighting from the ‘sun’ that is scattered back due to atmosphere etc). You would often have the directional lighting movable (change time of day) or point lights (something attached to an actor)… IMO. the point is that static lighting (eg light maps) take a lot of computational effort on the devs computer - but doesn’t take much computation on the users computer (and vice versa).

[ClockworkOcean]

From the docs: