Seams on normal map.

Sanches

Hello there. I know there was  lot of similar topics and i read a lot of them (I really did ). Also checked out a wiki articles about normal mapping but still can't solve my problem. I did a test bake and in the first look the model with normal map looks fine.

But if zoom close enough there is a seam where UV shells separated:

My workflow:
1. Creat high\low poly in max.
2. Unwrap the low poly in max.
3. Assign different smoothing groups to different UV shells.
4. Create a cage.
5. Export low\high poly and cage as obj (before export low poly triangulated, reset xform applied, modifier stack collapsed).
6. Import to xNormal.
7. Bake normal map.
Here is my UV:

Normal with smoothing groups:

High ploy and low poly:

And xNormal settings:

Also i get the same result when exporting as FBX with one smoothing group.

wannabe

My guess would be it is the way you unwrapped your lowpoly. That 90° angle of the box shares the same uv island with two sides of your box so the normal map tries to compensate for the extreme angle change (correct me if i am wrong). You can fix it by either placing your seams at the sharp angles and producing more islands or you could bevel these edges to avoid the effect. 

Sanches

wannabe said:

My guess would be it is the way you unwrapped your lowpoly. That 90° angle of the box shares the same uv island with two sides of your box so the normal map tries to compensate for the extreme angle change (correct me if i am wrong). You can fix it by either placing your seams at the sharp angles and producing more islands or you could bevel these edges to avoid the effect. 

Thanks for the response @wannabe But the problem i'm talking about is not here.

The problem actually appears here, in this area:

ZacD

Make sure the high poly and low poly are perfectly aligned.

See if the error goes away with a higher resolution bake.


My guess is the resolution of the normal map isn't high enough to perfectly handle the shading when zoomed that far in. The artifact is small enough that it should just be ignored, plenty of video games ship with issues much worse than this with textures.

zachagreg

I agree with ZacD throw a base texture on there first and see if it's even noticeable from a reasonable distance. A player would never be able to get that close to an object in 99% of use cases unless you're intending for this to be in VR and actively being picked up and inspected.

Sanches

ZacD said:

Make sure the high poly and low poly are perfectly aligned.

Cheked it for a few times, looks good. 

ZacD said:

See if the error goes away with a higher resolution bake.

Yep, it still there.

ZacD said:

 The artifact is small enough that it should just be ignored, plenty of video games ship with issues much worse than this with textures.

So, in general it's fine to have this small artifacts on the normal map? Am i right?

zachagreg said:

I agree with ZacD throw a base texture on there first and see if it's even noticeable from a reasonable distance. A player would never be able to get that close to an object in 99% of use cases unless you're intending for this to be in VR and actively being picked up and inspected.

In the normal distance this artifacts aren't noticeable at all.

zachagreg

Yes small artifacts like that are normal (no pun intended) when having hard edges like that. It's due to the fact that a hard edge is in essence splitting that edge. The only thing I would look at changing on the highpoly is that inset edge that runs the perimeter of the blue piece. That inset is super sharp resulting in just a few pixels of data which is why you can see the aliasing along that edge even in the zoomed out first picture you posted. 

Sometimes it is necessary to exaggerate bevels and insets for them to read correctly in 3D.



Read through the first couple posts of these threads to get a more holistic understanding. (I know you already read through some of the posts similar to your own this is just for assurance sake. )

https://polycount.com/discussion/107196/youre-making-me-hard-making-sense-of-hard-edges-uvs-normal-maps-and-vertex-counts/p1
https://polycount.com/discussion/81154/understanding-averaged-normals-and-ray-projection-who-put-waviness-in-my-normal-map/p1

Sanches

Thanks a lot guys.