Large BuildData Files

How can I profile what is making my BuildData files quite so large. For some of my levels they are 10MB and others 3GB

I have experienced a map file which is simple, but the size is ridiculously big. In my case, it is due to lightmass - the lightmap size are too big and after further tweak, the size is reduced by ~ 14x smaller (700MB -> 50MB).

I really would like to know how you decreased so much the build data. Just refining the lightmap resolutions?

I have the same issue. I have quite a simple level, but it’s BuildData size is about 850 MB. Changing the lightmap resolutions to about 1/16 of the original size (For most of the assets I went from 1024 to 256), I only reduced the size to 830 MB. What else could make the file so huge?

After some investigation… In my case it was due to a huge reflection capture resolution. After going from 2048 to 1024 the size dropped (as expected) to about 1 / 4.

For anybody interested in this. We were just looking into reducing memory and noticed that BuildData for maps were up to 380MB for some streaming levels which was making things worse. A first test of changing Volume Light Sample Placement Scale from 1 to 40 (in world settings tab) made us go down from 380MB to 29MB. I haven’t checked anything else yet but I’d start looking there. Btw we’re using Sparse volume Lightning Samples because volumetric is not supported in streaming levels