Substance Painter - Normal Seam Issue - UV size?

LaughinTea

Hi,
Apologies if I am going about this the wrong way, I've been hunting around for an explanation but have not been able to find any:

I've noticed that when baking a simple cube in Substance Painter I get a minor line going down the hard edge. I expected this to be smooth as I've used:

• average normals in the bake (Substance Painter)
• Separate UV islands for each side of cube (Maya)
• Hard edges on all edges of the cube (Maya)

I've noticed that when increasing the size of the UVs in the 0-1 space, it fixes the problem:


So I have a couple of questions;

• Is there a way to solve this without increasing the UV size - UV space is tight as this is part of a larger asset

• Since its not overly noticeable, should I even be concerned? Could there be issues further down the pipeline? (or am I being obsessive?)

Thanks in advance

rollin

Hi, what texel density we're talking about? Might be a bleeding issue

Obscura

I don't think you should be concerned much, I can barely see the error and I'm probably not alone with this.

LaughinTea

rollin said:

Hi, what texel density we're talking about? Might be a bleeding issue

Hey, so I've been working with 2k in Substance Painter. Yeah I think it could be a pixel issue since the sizing of the UV seems to help. But I thought that at this resolution, even with small UV shells, I shouldn't be seeing any issues?

LaughinTea

Obscura said:

I don't think you should be concerned much, I can barely see the error and I'm probably not alone with this.

Hey, yeah you are probably right, my concern is just when it happens on bigger more important areas of the mesh. But like you say, its difficult to see and probably can be hidden by applying materials etc to it. I just like to understand whats actually going on

rollin

LaughinTea said:

rollin said:

Hi, what texel density we're talking about? Might be a bleeding issue

Hey, so I've been working with 2k in Substance Painter. Yeah I think it could be a pixel issue since the sizing of the UV seems to help. But I thought that at this resolution, even with small UV shells, I shouldn't be seeing any issues?

It depends on the texel density. A 2k texture doesn't say anything without knowing the uv-space of the element.

LaughinTea

rollin said:

LaughinTea said:

rollin said:

Hi, what texel density we're talking about? Might be a bleeding issue

Hey, so I've been working with 2k in Substance Painter. Yeah I think it could be a pixel issue since the sizing of the UV seems to help. But I thought that at this resolution, even with small UV shells, I shouldn't be seeing any issues?

It depends on the texel density. A 2k texture doesn't say anything without knowing the uv-space of the element.

Oh right sorry, how would I know the exact texel density? I've only been basing it on maximising the UV space. Using Maya 2019 UV tool 'Get average texel density from faces' gives me between 6 & 7 px/unit

Thanez

When ppl ask for texel density when a baked edge is in question, they're wondering how many pixels wide the edge is represented as on the baked normal map. 

A 90° lowpoly with hard edges will never render perfectly. If you zoom in, you can see the limitations of the texel density of the edge. Look closely at the edge on your normal map. You're expecting 5 pixels worth of normal map information to render a variation of 0°-45° between the lowpoly and highpoly. Even with interpolation between pixels that's gonna be an issue, so you render to a 32768*32768 px image, you've given the edge all of the pixels in the gorram universe in the normal map to do it's job, but as you zoom closer you see banding all over. Your bit rate is too low. So you bake it to a 32768*32768 32bit image, taking up 4GB of VRAM, but then you zoom so close that you'll be able to see the difference between 44,995° and 45°, and that's when you realize both that you've gone mad, and the fact that when you separate two planes by a hard edge and a split in the UVs you also break any and all interpolation between the two planes' shading and their respective pixels. If you zoom close enough, you'll be able to see it.
So you start going to counselling for your self-inflicted madness, zoom out, apologize to your partner in a grand fashion, remove the hard edge, hug your kids and start rebuilding their trust in you, chamfer the edge, work your self-esteem back to where it once was, weld the UV seam and bake it to a 1024*1024. Three years have passed, as you look back and count the vertexes is when you realize, that chamfering the edge costs the same as having a hard edge and a split in the UVs. 

Oh and if you just don't wanna chamfer for whatever reason, once you slap a texture on that MAD CUBE, the limitations of the normal map will be mostly hidden. Just, don't. zoom. in.

poopipe

That was pure poetry

Gold star for you

rollin

@Thanez
I deeply thank you for .. this! 

LaughinTea

@Thanez - thanks! Very descriptive and yes I see your point. Yup, its pretty much invisible with textures added! Good to know all that though so thanks everyone!

annebakerim

Your bit rate is too low. So you bake it to a 32768*32768 32bit image, taking up 4GB of VRAM, but then you zoom so close that you'll be able to see the difference between 44,995° and 45°,http://bakerim.com/ and that's when you realize both that you've gone mad, and the fact that when you separate two planes by a hard edge and a split in the UVs you also break any and all interpolation between the two planes' shading and their respective pixels. If you zoom close enough, you'll be able to see it