Source control for generated Lightmap UVs?

We have a lot of buildings/meshes for which Unreal Editor does the Lightmap UVs generation as it packs UVs really well, however, whenever someone in the team makes some changes and submits the assets to subversion/source control, the Lightmap UVs are re-generated on EVERY workstation that does an update.
And when Lightmap UV resolutions are high enough this can easily take up to an hour per workstation (on completely clean checkouts), which is downright unacceptable.

My question is, why?, where is the data stored? why doesn’t source control pick this up, or why does Unreal need to re-generate this data when it clearly has already been done.

It’s putting quite a dent into an otherwise nice workflow.

Any pointers in the right direction would be welcome.

Hi svenneve,

If you have not discovered this already, you can navigate to the Lightmaps under World Settings, open them in their own window and select File>Connect to Source Control>Run without Source Control.

Let me know if this does not answer your question.


It’s not the lightmap data in it self that is the problem, it is when an mesh asset has been updated the lightmap UVs get regenerated (which with heavy meshes with lots of small UV islands can take a long long time.)

But i think that might have to do with the Derived Data Cache being locally stored, I haven’t tried putting it on our shared network drive as that project has been delivered at this point.

But it is something i’m going to try should we do another Unreal Engine based project.

You are correct. Using a shared DDC would resolve this issue as described in the following documentation:

Derived Data Cache