Geometry Node: Vector in face corner domain have different interpolation method unlike general uv for subdivision #102189

New Issue

Rincewind · 2022-10-31T18:19:46+01:00

Rincewind commented

2022-10-31 18:19:46 +01:00

System Information
Operating system: Windows-10-10.0.19044-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 2080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 516.40

Blender Version
Broken: version: 3.3.1, branch: master, commit date: 2022-10-04 18:35, hash: b292cfe5a9
Worked: Never

Short description of error
Geometry Node: Vector in face corner domain have different interpolation method unlike general uv for subdivision

The UV island interpolation algorithm allowed the mesh and texture coordinates to intersect freely to keep lines parallel when subdivided.
When using the general vector attribute, the subdivision uses simple averaging.
The result of this is that geometrically parallel lines can be visually curved.

2022-11-01 21-42-33.mp4

Exact steps for others to reproduce the error

Subdivide an arbitrary mesh with common vector attributes and build a grid on the render from them to see the deformation.
Or check the example file:

FaceCornerVectorNotUVforSubdiv.blend

**System Information** Operating system: Windows-10-10.0.19044-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 2080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 516.40 **Blender Version** Broken: version: 3.3.1, branch: master, commit date: 2022-10-04 18:35, hash: `b292cfe5a9` Worked: Never **Short description of error** Geometry Node: Vector in face corner domain have different interpolation method unlike general uv for subdivision The UV island interpolation algorithm allowed the mesh and texture coordinates to intersect freely to keep lines parallel when subdivided. When using the general vector attribute, the subdivision uses simple averaging. The result of this is that geometrically parallel lines can be visually curved. [2022-11-01 21-42-33.mp4](https://archive.blender.org/developer/F13834719/2022-11-01_21-42-33.mp4) **Exact steps for others to reproduce the error** Subdivide an arbitrary mesh with common vector attributes and build a grid on the render from them to see the deformation. Or check the example file: [FaceCornerVectorNotUVforSubdiv.blend](https://archive.blender.org/developer/F13834732/FaceCornerVectorNotUVforSubdiv.blend)

Rincewind commented

2022-10-31 18:19:46 +01:00

Added subscriber: @Rincewind3D-1

Iliya Katushenock commented

2022-10-31 18:28:57 +01:00

Added subscriber: @mod_moder

Iliya Katushenock commented

2022-10-31 18:28:57 +01:00

#85962

Iliya Katushenock commented

2022-10-31 18:54:25 +01:00

Checking...

Iliya Katushenock commented

2022-10-31 19:04:31 +01:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Iliya Katushenock commented

2022-10-31 19:04:31 +01:00

So far, I see that the problem is simply in the subdivision. More precisely, perhaps it is his method of interpolation. Need a higher opinion.

Rincewind commented

2022-10-31 19:29:26 +01:00

Interesting, yes in this the example file it's the subdivision.

But in my real-world project, there's also a distortion in the base mesh without subdivision.

Not sure what's here different from my simplified example with Suzanne. Unfortunately, I can't share my real-world example, but here are two screens of the distorted UV, just by adding the geometry node to the base mesh:

However, both UV distortions are serious issues for displacement maps.

I try to investigate more and hopefully find a way for a simplified example for the other issues and make a second ticket for that one separately.

Interesting, yes in this the example file it's the subdivision. But in my real-world project, there's also a distortion in the base mesh without subdivision. Not sure what's here different from my simplified example with Suzanne. Unfortunately, I can't share my real-world example, but here are two screens of the distorted UV, just by adding the geometry node to the base mesh: ![g8.1 with geocraft.png](https://archive.blender.org/developer/F13825606/g8.1_with_geocraft.png) ![g8.1 without geocraft.png](https://archive.blender.org/developer/F13825607/g8.1_without_geocraft.png) However, both UV distortions are serious issues for displacement maps. I try to investigate more and hopefully find a way for a simplified example for the other issues and make a second ticket for that one separately.

Iliya Katushenock commented

2022-10-31 19:38:03 +01:00

I can imagine that this may have something to do with the fact that UVs are in nodes, this is a 3d vector. Maybe changing the 3rd axis can somehow affect this offset. But that's just my guess. If you want to explore this, you can also pay attention to it.

Rincewind commented

2022-11-01 00:06:56 +01:00

I figured out what the other distortion caused I mentioned: It's a mask modifier.

So we have two different types of UV distortion:

One caused by the combination of geo-node and subdivision (this ticket)
One caused by the mask modifier

The UV distortion, which is caused by the mask modifier, seems not to hurt my displacement textures, so I guess it's, for now, a non-issue and can be ignored.

The one caused by geo-node and subdivision is still an issue and should be continued to inspect by the developers.

I figured out what the other distortion caused I mentioned: It's a mask modifier. So we have two different types of UV distortion: - One caused by the combination of geo-node and subdivision (this ticket) - One caused by the mask modifier The UV distortion, which is caused by the mask modifier, seems not to hurt my displacement textures, so I guess it's, for now, a non-issue and can be ignored. The one caused by geo-node and subdivision is still an issue and should be continued to inspect by the developers.

Rincewind commented

2022-11-01 00:19:37 +01:00

Okay, it looks like I was too fast with my conclusion.

A mask modifier distorts the mesh in combination with that geo-node while using base mesh.

That's probably an issue. I will investigate more and then create for that second issue a separate ticket.

Okay, it looks like I was too fast with my conclusion. A mask modifier distorts the mesh in combination with that geo-node while using base mesh. That's probably an issue. I will investigate more and then create for that second issue a separate ticket.

Iliya Katushenock changed title from ~~Geo node join and merge by distance distorts the UV map~~ to Geometry Node: Vector in face corner domain have different interpolation method unlike general uv for subdivision

2022-11-01 19:53:38 +01:00

Iliya Katushenock commented

2022-11-01 19:53:38 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Confirmed'

Iliya Katushenock commented

2022-11-01 19:53:38 +01:00

Added subscriber: @HooglyBoogly

Iliya Katushenock commented

2022-11-01 19:53:41 +01:00

Hello again. Thanks for the report. After a little investigation, I can confirm this report, as well as slightly modify it to be more specific about the problem you describe. If you have any other errors not related to this case, you can open new reports with new examples.

Hans Goudey commented

2022-12-22 19:03:08 +01:00

Changed status from 'Confirmed' to: 'Archived'

Hans Goudey closed this issue

2022-12-22 19:03:08 +01:00

Hans Goudey commented

2022-12-22 19:03:08 +01:00

Thanks for the report. I wouldn't call this a bug though. The attribute created by the Store Named Attribute node isn't a UV map, so it doesn't get the special UV map interpolation during subdivision. There are two ideas to address this:

Allow creation of "proper" UV maps with geometry nodes: f0dc4d67e5 combined with D14365
Allow adding meta-data to attributes when creating them to change how they're interpolated: No specific design or implementation task yet

Thanks for the report. I wouldn't call this a bug though. The attribute created by the Store Named Attribute node isn't a UV map, so it doesn't get the special UV map interpolation during subdivision. There are two ideas to address this: 1. Allow creation of "proper" UV maps with geometry nodes: f0dc4d67e5 combined with [D14365](https://archive.blender.org/developer/D14365) 2. Allow adding meta-data to attributes when creating them to change how they're interpolated: No specific design or implementation task yet

Rincewind commented

2023-01-31 09:27:17 +01:00

@HooglyBoogly

Just tested this one in 3.5 Alpha.

Of course, still broken ;)

Is there any design task for "adding meta-data to attributes when creating them to change how they're interpolated" yet? ;)

@HooglyBoogly Just tested this one in 3.5 Alpha. Of course, still broken ;) Is there any design task for "adding meta-data to attributes when creating them to change how they're interpolated" yet? ;)

Rincewind commented

2023-04-04 23:39:33 +02:00

@HooglyBoogly

was is this issue closed?
It's still not fixed.

@HooglyBoogly was is this issue closed? It's still not fixed.

Hans Goudey commented

2023-04-04 23:44:55 +02:00

It should work better now, if the data is stored as a 2D vector attribute on the face corner domain by the store named attribute node.

Rincewind commented

2023-04-04 23:47:08 +02:00

Unfortunatelly, can't confirm.

In the Blend file at the start of this ticket, the UV map still deforms like it was before:

Unfortunatelly, can't confirm. In the Blend file at the start of this ticket, the UV map still deforms like it was before: ![grafik](/attachments/5c33d607-99cf-47c1-918a-65a05857c7c1)

grafik.png

658 KiB

Hans Goudey commented

2023-04-04 23:50:27 +02:00

You're using the 3D vector type, not 2D.

Rincewind commented

2023-04-04 23:57:13 +02:00

confirmed, but is fixed. Also my original example is now working which was replaced is now working as intented.

sadly I can't test my real world example, where I discovered this issue, after Blender is crashing when I start rendering in Cycles ;)

But this is an other ticket, once I gathered more details.

thanks.

confirmed, but is fixed. Also my original example is now working which was replaced is now working as intented. sadly I can't test my real world example, where I discovered this issue, after Blender is crashing when I start rendering in Cycles ;) But this is an other ticket, once I gathered more details. thanks.

Rincewind referenced this issue

2023-04-05 00:51:44 +02:00

Geometry Node: Order of connection to Join Geometry node affect on shader local space #106578

Rincewind commented

2023-04-05 00:53:20 +02:00

I created a follow up.
There seems to be still an issue with normals: #106578

The crash seems to be related to hair paticles. I will also create a follow up once I have a simpilfied reproducable test case.

I created a follow up. There seems to be still an issue with normals: #106578 The crash seems to be related to hair paticles. I will also create a follow up once I have a simpilfied reproducable test case.

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Geometry Node: Vector in face corner domain have different interpolation method unlike general uv for subdivision #102189