Ability to store lightmap data in separate files

Hi guys,

This isn’t a bug, but just something we’re encountering on our project that’s causing a bit of a headache.

UE4 looks to store the lightmap data for shadowing etc in the umap files, this means that the map files can get rather large in size (as an example, the largest map in our project is 308MB with lightmaps, and about 7MB without).

There are 2 of us working on the project and we transfer data over GIT regularly, this means that a small change to a map, like removing or placing a static mesh or just editing an actor, requires the entire map file to be sent, including all lightmap data, even if that data hasn’t changed at all.

Is it possible to (optionally of course) get the lightmap data to be stored outside of the map files? The main benefit I can see to this is that the lightmaps could potentially be excluded from GIT commits (or similar) meaning that only the now relatively smallish map files need to be sent when a change is made. The downside here is that both users would need to locally rebuild lighting, but it’d save the 30/40 minute push/commit times that we’re seeing currently.

Just wondering if this is possible currently, and if not, is it something that could potentially be added?