Lines (seams) artifacts are visible on the edges

Assassin115

Hello Everyone.

I've been trying to fix these artifacts for a long time but didn't succeed so maybe you could help me with that.

 

Basically, I've created some objects in Blender, both low and high poly:

Low:

High: 

I've marked seams on hard edges and unwrapped the low poly:

Then I exported both models to SP. I've been using these settings for baking:

Once the baking was done, these lines on the edges appeared:

However, if I zoom out, these lines become less visible:

Even though they are not really visible from a distance, I still want to fix these artifacts, if it is possible of course.

 

Then I duplicated the low poly three times and made some adjustments to the new objects:

They are separate objects with suffixes _low and _high on all eight of them.

Here are the uvs:

However, once the baking was done, these lines have become more visible on the edges:

I've been looking through the forums searching for an answer to my problem, I've tried everything to fix these artifacts, but worthless. I'm desperate for the solution so I'd really glad if somebody could help me.

Kanni3d

Could be something much deeper than this, but worth trying first since it's a simple and quick troubleshoot - export these out and apply them in your target renderer/engine just to rule out some factors. If it shows up fine there, then you're good, Painter's viewport tends to do this when the mesh/process is totally fine.

If it still looks bad in the target engine/renderer, then we can try looking deeper.

poopipe

You cant fix this without compromising something else. 

If you are going to get close enough to see the artefact you get close enough to need geometry to support the shape.  By that I mean your low poly needs rounded edges

Assassin115

@Kanni3d Hey, thanks for replying.

I exported textures into Blender (normal map set to OpenGL cause this is what Blender uses) and applied them on the model. However, these weird lines on the edges are still visible. You said we can look deeper, do you have any suggestions?

Btw, some people on forums and Youtube have told me that this is maximum that you can get from such a low poly model and if it looks ok from a distance, then there is nothing to worry about. What you think about that or do you have any other solutions?

Assassin115

@poopipe Hi, thanks for replying.

I guess this is maximum that you can get from such a low polycount...

I mean, it is ok if these lines(seams) are not visible from a distance (if I zoom out), right?

poopipe

as with anything else - if you can't see the artefact in game, it's not there


the issue is that in practice a tangent space normal map can't quite represent 90 degrees from the face normal 

Assassin115

@Kanni3d Hi, You said that this might be something deeper, could you please give me any suggestions on that? Poopipe replied earlier that it is impossible to get rid of artifacts without rounding your edges on low poly. So, it’s just impossible to fix?

Assassin115

@poopipe Hey, I recently tried to add one segment bevel on my low poly and export it to SP. It kinda has a better result, yet the seams are still visible. Do you have any suggestions on that?

Kanni3d

seams with hard edge splits will always be visible, its just straight up a limitation of tangent space normals as poopipe mentioned.

However, adding a segment/chamfer allows you to remove the seam entirely by keeping it as one uv shell/one smoothing group (or smooth edges).

Assassin115

@Kanni3d Alright, I think I got it. It’s impossible to get rid of seams with such a low poly count. However, if you chamfer your low poly, then they should be gone. I’ll do some test baking soon with low poly edges chamfered and then I’ll share here

Kanni3d

However, if you chamfer your low poly

and assign a single soft edge/smoothing group and stitch the seams together ***

then they should be gone.

Don't forget those extra couple steps I just mentioned

Assassin115

@Kanni3d Alright, will do, thank you for explanation. I didn't quite understand the "stitch the seams together" part. What do you mean by that? I will however apply one smoothing group for all models.

Kanni3d

DON'T apply one smoothing group for the entire model - only the polygons you just chamfered get a single smoothing group.

Once they're a single smoothing group - stitch them.

EDIT: Here's another gif of that to be safe.

Assassin115

@Kanni3d Sorry man, I'm still getting into this workflow cause I didn't really have a lot of experience with baking 

Anyways, thank you a lot for getting into details, I think I've solved this problem:


Perfect bake, no visible seams at all!

I do actually have a little triangle if I get too close, but that's impossible to see from a distance (the model is not meant to be viewed in a close range) so I guess it's ok to have it, cause, well, it's a limitation of tanget space normals:

The edges are perfect btw:



It doesn't increase the polycount much so I'll continue chamfering my low polys (if necessary) cause they tend to give best results.

Thank you very much for helping me out, this issue has been stuck in my head for a while.

pior

You also need to know if the rays are being cast as a continuous cage shape, or broken at the edges.

Kanni3d

Thank you very much for helping me out, this issue has been stuck in my head for a while.

No prob !! Hope it helps, and don't forget as previously mentioned by others, this issue is mostly unavoidable and will never be seen at such extreme closeups like you have in your screenshots. Normal maps can only do so much

Use this technique on really important/large/close-up assets

gnoop

Assassin115 said:

, it's a limitation of tanget space normals:

for such model you don't  have to bake anything at all.     Can  fill your normal map with flat color  128,128,255   if you face weight  vertex normals

Assassin115

@ pior Could you please get more into details about rays and stuff that you wrote? Does it actually have any impact on my normal map? I kinda got what I wanted but I want to hear from other people too

Assassin115

&gnoop But what if I want to have details on the edges or on the surface if I import sculpted high poly into SP? This might probably be ok if you’re going for something cartoony/low poly style, which is definitely not what I’m looking for. Maybe I didn’t get what you were saying, could you please define your statement?

shogunato

There is also a super important factor witch is your texture resolution.  Seams will be more visibles with low res maps and by using small uvs shells. 

You can also try with mikkspace workflow if your target engine support it.

- Unwrap uvs with few seams and put 1 smth group on all the object.
- Disable FBX Tangents and Binormals when exporting


-Create new project with SP and Enable Compute tangent space per fragments

-Bake and see the result