Your lightmap UVs have too many splits in them which reduces the amount of space that's useful for texels because you have so much padding. You'd probably get a better result by letting UE4 autogenerate the lightmap UVs from the first UV set so that there's only one seam along the side of the vase.
Probably the ideal layout for vases like this would put the main vase seam towards the space between the vases and towards the wall so they're concealed. Probably you would need to have a few more splits on the twigs to be able to get a good pack. The way I do lightmap UVs is by autopacking my texture UVs in IPackThat and then pinning the border UVs back in Blender, turning on auto unwrap and UV sculpting, and nudging the UV borders to take up the maximum amount of space in the lightmap.
You want the least amount of islands possible. You can scale up small details that need more lighting information like the branches (on the right in my example).
Obviously clean up the UVs and packing more than what I've shown, I did it in 10 minutes.
If you're still having issues, could you post the obj and I'll throw it in UE4.
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Probably the ideal layout for vases like this would put the main vase seam towards the space between the vases and towards the wall so they're concealed. Probably you would need to have a few more splits on the twigs to be able to get a good pack. The way I do lightmap UVs is by autopacking my texture UVs in IPackThat and then pinning the border UVs back in Blender, turning on auto unwrap and UV sculpting, and nudging the UV borders to take up the maximum amount of space in the lightmap.
You want the least amount of islands possible. You can scale up small details that need more lighting information like the branches (on the right in my example).
Obviously clean up the UVs and packing more than what I've shown, I did it in 10 minutes.
If you're still having issues, could you post the obj and I'll throw it in UE4.