UV seams visible at distance with texpaint even with 8 px bleed & 0.1 filter size #44728

New Issue

WK Bong · 2015-05-16T15:22:23+02:00

WK Bong commented

2015-05-16 15:22:23 +02:00

System Information
Win7 64bit GTX 560ti
Win8 64bit GTX 980

Blender Version
Broken: 2.74.5 05c4c24

Short description of error
Today 1 beginner blenderhead brought the problem to my attention.
This file is extreme case where every edge is marked with seam. (lazy UV-ing)
This bug is very old, noticed it in 2.67 even.

In texpaint, with bleed of 8 px, UV seams appear as white lines with distance (camera to seams).
Visible in viewport (perspective, ortho) and in BI (perspective, ortho).
note: UV islands have enough gaps.

image sampling > Filter size (0.1) didn't help with more distance.

Exact steps for others to reproduce the error
SeamBug.blend

See flickering white lines on viewport.
Add more objects with array mod.
Then render.
You'll see seams with distance.

Only when you paint the whole texture in 1 color the seam will disappear.

**System Information** Win7 64bit GTX 560ti Win8 64bit GTX 980 **Blender Version** Broken: 2.74.5 05c4c24 **Short description of error** Today 1 beginner blenderhead brought the problem to my attention. This file is extreme case where every edge is marked with seam. (lazy UV-ing) This bug is very old, noticed it in 2.67 even. In texpaint, with bleed of 8 px, UV seams appear as white lines with distance (camera to seams). Visible in viewport (perspective, ortho) and in BI (perspective, ortho). **note**: UV islands have enough gaps. ![UV_gap_problem4.png](https://archive.blender.org/developer/F175473/UV_gap_problem4.png) image sampling > Filter size (0.1) didn't help with more distance. ![UV_gap_problem5.png](https://archive.blender.org/developer/F175483/UV_gap_problem5.png) **Exact steps for others to reproduce the error** [SeamBug.blend](https://archive.blender.org/developer/F175476/SeamBug.blend) 1. See flickering white lines on viewport. 2. Add more objects with array mod. 3. Then render. 4. You'll see seams with distance. Only when you paint the whole texture in 1 color the seam will disappear.

WK Bong commented

2015-05-16 15:22:23 +02:00

Changed status to: 'Open'

WK Bong commented

2015-05-16 15:22:23 +02:00

Added subscriber: @WeeKwongBong

Brecht Van Lommel commented

2015-05-17 14:20:54 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2015-05-17 14:20:54 +02:00

This is a classic problem with UV atlases and filtering in renderers.

In Blender Internal you can avoid the white lines by disabling mip maps and setting the filter size low enough. You then get aliasing instead though, and can't get rid of it because Blender Internal will only sample the texture once per pixel.

In Cycles such aliasing is solved by using more AA samples which will sample the texture multiple times per pixel, but that's slower to render. As far as I know that's the only solution to both avoid the bleeding and aliasing problems, so Blender Internal would need to get some way to sample textures multiple times per pixel to solve this.

This is a classic problem with UV atlases and filtering in renderers. In Blender Internal you can avoid the white lines by disabling mip maps and setting the filter size low enough. You then get aliasing instead though, and can't get rid of it because Blender Internal will only sample the texture once per pixel. In Cycles such aliasing is solved by using more AA samples which will sample the texture multiple times per pixel, but that's slower to render. As far as I know that's the only solution to both avoid the bleeding and aliasing problems, so Blender Internal would need to get some way to sample textures multiple times per pixel to solve this.

WK Bong commented

2015-05-17 14:37:51 +02:00

I found a temporary fix for this on BI.
Turn ON transparency on Material & Alpha influence on texture.
(something to investigate there)

But still, it looks pretty bad on viewport & BGE.
Since we are going to have better GLSL renderer, I think we should look into solving this properly.

I found a temporary fix for this on BI. **Turn ON transparency on Material & Alpha influence on texture.** (something to investigate there) But still, it looks pretty bad on viewport & BGE. Since we are going to have better GLSL renderer, I think we should look into solving this properly.

Brecht Van Lommel commented

2015-05-17 14:48:20 +02:00

I don't think enabling alpha really solves the problem. In the attached .blend file the space between the UV islands has alpha 0, and enabling alpha makes it black, which in this test file happens to be the same color as the UV islands themselves. But if the islands have a different color the issue shows up again.

If you want to solve this fully for GLSL, I guess you should look into limiting the mipmap levels to a certain number (e.g. 3 for pixel bleed 8). Then you get some aliasing which you can solve with multisample if necessary. Although I would expect the solution typically used in games to be just bleeding more than 8 pixels.

I don't think enabling alpha really solves the problem. In the attached .blend file the space between the UV islands has alpha 0, and enabling alpha makes it black, which in this test file happens to be the same color as the UV islands themselves. But if the islands have a different color the issue shows up again. If you want to solve this fully for GLSL, I guess you should look into limiting the mipmap levels to a certain number (e.g. 3 for pixel bleed 8). Then you get some aliasing which you can solve with multisample if necessary. Although I would expect the solution typically used in games to be just bleeding more than 8 pixels.

WK Bong commented

2015-05-22 09:35:24 +02:00

More renders of the case.

all rendered in BI

More renders of the case. ![UV gap problem1.png](https://archive.blender.org/developer/F178692/UV_gap_problem1.png) ![UV gap problem.png](https://archive.blender.org/developer/F178694/UV_gap_problem.png) ![UV gap problem6.png](https://archive.blender.org/developer/F178696/UV_gap_problem6.png) all rendered in BI

Sergey Sharybin commented

2015-05-26 12:03:29 +02:00

Added subscriber: @Sergey

Sergey Sharybin commented

2015-05-26 12:03:29 +02:00

Changed status from 'Open' to: 'Archived'

Sergey Sharybin closed this issue

2015-05-26 12:03:29 +02:00

Sergey Sharybin self-assigned this 2015-05-26 12:03:29 +02:00

Sergey Sharybin commented

2015-05-26 12:03:29 +02:00

Disabled alpha is indeed just a co-incident because your texture is black.

In Cycles we only have mipmaps only when using OSL backend, so this issue is not such a trouble there. And surely we can improve BI to support maximum mipmap level or to do more AA samples, but this is more a TODO item.

So thanks for the report, but archiving it now. Possible workarounds @brecht already mentioned here.

Disabled alpha is indeed just a co-incident because your texture is black. In Cycles we only have mipmaps only when using OSL backend, so this issue is not such a trouble there. And surely we can improve BI to support maximum mipmap level or to do more AA samples, but this is more a TODO item. So thanks for the report, but archiving it now. Possible workarounds @brecht already mentioned here.

WK Bong commented

2015-05-26 13:03:31 +02:00

@Sergey

"surely we can improve BI to support maximum mipmap level or to do more AA samples"

How that works? I'm curious.

@Sergey "surely we can improve BI to support maximum mipmap level or to do more AA samples" How that works? I'm curious.

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UV seams visible at distance with texpaint even with 8 px bleed & 0.1 filter size #44728