Bad lightmaps bake with manually unwrapped uvs

I’m a student and I’m experimenting with UE4, so sorry for the probably stupid question!
I made a simple pillar in 3DS Max, and I unwrapped two sets of uvs, one for texturing and one for the lightmaps (on channel 1). The lightmap uv:

I followed the guidelines, so there is no overlap, and the uvs are all normalized in the (0,1) space. I also scaled up the main section of the pillare (upper-left corner) so that it has more texture space for the bake.

I imported the model in UE4, and I attempted a bake with the standard settings (lightmap resolution for the model of 64x64, preview lightning quality) with a single point light with GI disabled to get more contrast.

This is the result:

You can see that right where two of the uv islands connect, there is an abrupt cut and it’s misaligned. So I tried to increase the lightmap resolution to 512.

And it looks good! No more seams. Now, obviously I know that an higher resolution will yield a more precise lightmap, but I was under the impression that I would be able to get a lightmap without seams even at a resolution of 64x64 (or at least that’s what I understood from the docs). So what could be the problem? Is my unwrap bad? Maybe I should leave more padding between all the pieces? Or is it normal?
Edit: Actually, even with a resolution of 512, the seam is still there, you just have to zoom in more to see it.

I also have this problem:

I put together a bunch of pillars, and even a 512 resolution, the floor looks like that. Now, between the “floor piece” of every pillar there is a bit of overlap (I couldn’t get it to snap together at the origin vertex so I overlaid them a bit to avoid gaps). Is that the problem? I of course would like a smooth transition between the center and the edges, not this concentric effect.

Thank you very much for your help! :slight_smile: