Question on Normal map baking - seeing lines between UV islands

[Deleted User]

Hello!

First post here so be gentle, but my question/problem has to do with the proper way of baking normal maps. What I'm trying to do in this test bake is bake this high poly cube to a low poly cube. I've followed all the rules that I've found on the subject including the biggest one I can think of, which is to split UV islands where I have hard edges and having some padding. But the problem I'm getting is, which is shown in the pics, is the line showing up on the texture. On the lit texture you can barely make it out, but there is a thin line where the UV islands break, and in the texture pic, it looks like the reason for this to me is that the gradient doesn't match up. It has a total reverse with no blurred transition in between. 

So my question is:

1. Is this normal for this method of normal baking?
2. If it isn't, what am I doing wrong?

Thank you in advance for all the feedback/answers you guys can give me!

Obscura

The gradiation should not match if you have some splits, and rotated uv parts because this is a tangent space normal map...And the coloration of the gradiation depends on the rotation of the uvs. I don't know how bad new is this to you, but basically you will never be able to 100% get rid of those lines. But as you say, its barely visible, and if it would get textured, it would be even harder to point it out.

Maybe you can reduce it a little bit with increasing the resolution, and with using perfect edge padding, but actually it would be just a waste of time.

[Deleted User]

Ok, thanks.

It is just confusing me because I've been checking out some of the assets from unreal engine 4, particularly ones created by epic games that are used in their demos, and they don't seem to follow this rule but somehow get better looking normals. What I mean is, for instance I was looking at this bulkhead prop they used in their Infiltrator demo. The entire model was  smoothed, no hard edges, but when you look at the normal map it doesn't have those high gradients you usually get when you do it that way. And also, all the edges you would think would be split in the uv map where just flattened into a planar map. I would show you but I'm not sure about Polycounts and Epic's policy on showing their assets online. And I've also noticed it was done the same way in assets I could look at in some AAA games. Games like skyrim, the Witcher 3, and DA: I. In all of those, they don't seem to be following the rule of hard edge split/padding UVs when they do have hard edges and when they don't, they somehow don't get those high gradients. I'm just confused how they are doing it. 

AtticusMars

Can't judge without seeing pictures but generally speaking, if you put enough geometry in your mesh and you'll get a normal map with minimal gradients no matter how it is smoothed. Especially if you bevel corners, which they more than likely did for the infiltrator demo.

Also... They must be following at least the "If you have a hard edge you must have a UV split with padding" rule, because the model won't bake properly without it.