Lightmapping, Streaky Shadows

Greetings. I’m new to lightmapping and lighting in general. I figured out how to create basic maps but have noticed a bunch of streaky lines in some places. I’ll include some pictures to show what I mean. All of the objects have a material that is just a plain colour, no albedo, so it should have a consistent shadow/colour.

Other, less random, shadows appear along the seams of all my touching objects. They are touching seamlessly, and there are no artifacts when I use realtime lights. In all my baked scenes I see a dark shadow along each touching edge.

My secondary issue, which is shown in the first image, is that I have two models that I made in blender, exported as .obj files, and imported into unity. They both start off the same colour, with the same settings (so far as I can tell). However, in the lightmap, one of the models goes super light and the other stays pretty much the proper colour. In the image they are the dark grey/black objects in the corners of the middle, and the super light streaky grey object in the middle of the edges of the object in the center.

You need to add padding to your UV island

What do you mean “padding”?

Google says padding in relation to uvs is adding a little border to the uv areas (known as islands). It’s just correct terminology in this case.

I think the poster wanted you to try giving the texel area some more space between so they don’t overlap.

Do you have any co-planar surfaces? It seems based on the look of some parts, that the uvs in general are a little messed up or you have double faces.

Is Unity generating lightmap UVs for you?

What version of Unity?