uv baking issues

kstar_1

 i unwrapped it in blender 2.8 and baked it in substance painter. im not really sure why the corners of the models arent lining up properly . when i looked at the uv map in blender and looked at the checker pattern to see if there was stretching. there was very little stretching in the four corners on the upper part of the model. 

Ghogiel

Looks like they do line up to me XD

Because the orientation of the UV shells are all different, the colors that are written to them need to be different too. In effect you have different colors across the UV shells/seams. If the colors were matching with that UV layout, the normal map would be making seams and transforming the light reflection in odd directions compared than what you probably want.

If the shells were all lined up and orientated to the same way, the colors in the normal would look a lot more similar.

The real question is > what does it look like with the normal map applied on a regular material?

kstar_1

you mean like this ? you can see the lines on the corners of the upper part of the model 

kstar_1

you can see the lines on the corners of the model just like the normal map above

Ghogiel

Those are mostly because the texture breaks at the UV seams, not optimally placed seams and smooth shading the low poly model and hoping the normal map can compensate. A general indicator these sorts of issues will occur is that if the low poly shades badly before a normal map is ever on there.

The harsh gradients in a normal map on smooth shaded low poly models and obviously placed UV seams are not the best way to go about things imo. Seams are going to show up a tiny tiny bit anyway with a reflective glossy mat. Any texturing that doesn't tile across and breaks at the seams is going to highlight where the seams are even more.

expected results:

You still see the seams a glancing angles.

The thing to do most of the time is put UV seams in better places and use hard edges. You could also use bevels and smooth shaded and/or face weighted normals to combat the extreme shading
Something more like this

kstar_1

omg that helps so much. iv asked on other forums and they havent been able to help. do hard edges replace the normal seem when you unwrap? if you use blender 2.8 is it mark sharp if there isnt a hard edge option?

Ghogiel

Yes mark sharp sounds right.

As for do hard edges replace the normal seam, I'm not quiite sure what you mean by that. But just make sure to stick UV seams every where you set an edge hard (or else there will be another type of visible bad seam).  And jset up those hard edges in places where you think shading is looking a litle extreme on the low poly (like edges that have 90 degree angle changes on their faces) and you should be ok as a general guideline

kstar_1

like instead of the uv seem that you use to unwrap , do you stick a hard edge there instead. or a uv seem on top of the hard edge

kstar_1

 i put a sharp edge and uv seem in that corner in front and still get that seem 

Kanni3d

Seems to be texture related which is another issue altogether. Try using tri-planar mapping rather than UV in that textures fill layers.