ray offsetting giving precission problems / render artifacts / cracks on far away geometry #43835

New Issue

Yousef Harfoush · 2015-02-28T01:38:25+01:00

Yousef Harfoush commented

2015-02-28 01:38:25 +01:00

System Information
windows 8.1.1 x64, geforce 660

Blender Version
Broken: tested 2.65 till 2.73 #bbf09d9
Worked: !

Short description of error
strange cracks appear on model in cycles render, if i reset rotation most of them disappears, if i reset position all then disappears.

Exact steps for others to reproduce the error

after opening shift-z to render and you'll see these cracks:strange_cracks.blend
reset rotation -> some disappears
reset position -> all disappears

i have checked the mesh no overlapping !

**System Information** windows 8.1.1 x64, geforce 660 **Blender Version** Broken: tested 2.65 till 2.73 #bbf09d9 Worked: ! **Short description of error** strange cracks appear on model in cycles render, if i reset rotation most of them disappears, if i reset position all then disappears. **Exact steps for others to reproduce the error** - after opening shift-z to render and you'll see these cracks:[strange_cracks.blend](https://archive.blender.org/developer/F146211/strange_cracks.blend) ![strange_cracks.png](https://archive.blender.org/developer/F146204/strange_cracks.png) - reset rotation -> some disappears ![strange_cracks_reset_rotation.png](https://archive.blender.org/developer/F146206/strange_cracks_reset_rotation.png) - reset position -> all disappears ![strange_cracks_reset_posistion.png](https://archive.blender.org/developer/F146208/strange_cracks_reset_posistion.png) i have checked the mesh no overlapping !

Yousef Harfoush commented

2015-02-28 01:38:25 +01:00

Changed status to: 'Open'

Yousef Harfoush commented

2015-02-28 01:38:25 +01:00

Added subscriber: @bat3a

blender-admin commented

2015-02-28 01:38:25 +01:00

#94830 was marked as duplicate of this issue

blender-admin commented

2015-02-28 01:38:25 +01:00

#94175 was marked as duplicate of this issue

blender-admin commented

2015-02-28 01:38:25 +01:00

#94205 was marked as duplicate of this issue

blender-admin commented

2015-02-28 01:38:25 +01:00

#93346 was marked as duplicate of this issue

blender-admin commented

2015-02-28 01:38:25 +01:00

#94056 was marked as duplicate of this issue

blender-admin commented

2015-02-28 01:38:25 +01:00

#91758 was marked as duplicate of this issue

blender-admin commented

2015-02-28 01:38:25 +01:00

#88723 was marked as duplicate of this issue

blender-admin commented

2015-02-28 01:38:25 +01:00

#87617 was marked as duplicate of this issue

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2015-02-28 01:38:25 +01:00

#87301 was marked as duplicate of this issue

blender-admin commented

2015-02-28 01:38:25 +01:00

#84676 was marked as duplicate of this issue

blender-admin commented

2015-02-28 01:38:25 +01:00

#84500 was marked as duplicate of this issue

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2015-02-28 01:38:25 +01:00

#82721 was marked as duplicate of this issue

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2015-02-28 01:38:25 +01:00

#79679 was marked as duplicate of this issue

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2015-02-28 01:38:25 +01:00

#54284 was marked as duplicate of this issue

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2015-02-28 01:38:25 +01:00

#52994 was marked as duplicate of this issue

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2015-02-28 01:38:25 +01:00

#51034 was marked as duplicate of this issue

Sergey Sharybin was assigned by Bastien Montagne

2015-02-28 14:40:10 +01:00

Bastien Montagne commented

2015-02-28 14:40:10 +01:00

Added subscriber: @mont29

Bastien Montagne commented

2015-02-28 14:40:10 +01:00

Think you are hitting a float precision limit here, your model is rather small and quite far away from origin. Yet, I would not expect that kind of issue to happen so soon (not even three orders of magnitude between size and offset)…

Sergey, this one is for you too I guess?

Think you are hitting a float precision limit here, your model is rather small and quite far away from origin. Yet, I would not expect that kind of issue to happen so soon (not even three orders of magnitude between size and offset)… Sergey, this one is for you too I guess?

Yousef Harfoush commented

2015-02-28 15:44:58 +01:00

the model is ~0.4 cubed, which is normal for a character, also this sample is taken from a big environment, in which the character should be in place to act.

Yousef Harfoush commented

2015-03-01 16:07:25 +01:00

any progress or a work around? my chars. already been animated and i still can't render them, thank you.
and sorry to annoy.

any progress or a work around? my chars. already been animated and i still can't render them, thank you. and sorry to annoy.

Sergey Sharybin commented

2015-03-02 09:57:28 +01:00

@bat3a, it's not strictly speaking easy to solve issue, seems machine arithmetic backfires here.

The possible workaround is to scale the scene up.

@bat3a, it's not strictly speaking easy to solve issue, seems machine arithmetic backfires here. The possible workaround is to scale the scene up.

Yousef Harfoush commented

2015-03-02 16:29:26 +01:00

 The possible workaround is to scale the scene up.

i didn't understand, you mean the scaling assets! which i tried but couldn't because they are already animated.

i also understand it may need time to resolve, thanks for your time.

``` The possible workaround is to scale the scene up. ``` i didn't understand, you mean the scaling assets! which i tried but couldn't because they are already animated. i also understand it may need time to resolve, thanks for your time.

Campbell Barton commented

2015-03-11 06:59:50 +01:00

Added subscriber: @ideasman42

Campbell Barton commented

2015-03-11 06:59:50 +01:00

The problem isnt exactly the object scale, Its the size of the object combine with it being nearly 160 units away from the scene center.

160 isn't really all that big though. (typically these issues happen at around ~5000+).

The problem isnt exactly the object scale, Its the size of the object combine with it being nearly 160 units away from the scene center. 160 isn't really all that big though. (typically these issues happen at around ~5000+).

Sergey Sharybin commented

2015-03-11 07:45:57 +01:00

@ideasman42, it's not that huge numbers to make single precision floats to become an issue imo. But i still didn't nail the root of the issue down and it'll take some time still i'm afraid.

marc dion commented

2015-03-13 14:38:11 +01:00

Added subscriber: @MarcClintDion

marc dion commented

2015-03-13 14:38:11 +01:00

This comment was removed by @MarcClintDion

*This comment was removed by @MarcClintDion*

Yousef Harfoush commented

2015-03-13 16:21:40 +01:00

@MarcClintDion: even if the scale is big, it is very expected, the character head in the sample is ~0.4 unit which is near human, also the environment scale is almost real, so this should not happen at the very least.

also the problem is that i already animated the chars.,i use a simple workflow -my team is very small actually 2- it's just single file that contains everything, so the full environment with various scenes are game like, if i needed a shot i move the chars. to the scene place, so taking the chars to origin is very hard if not impossible.

@MarcClintDion: even if the scale is big, it is very expected, the character head in the sample is ~0.4 unit which is near human, also the environment scale is almost real, so this should not happen at the very least. also the problem is that i already animated the chars.,i use a simple workflow -my team is very small actually 2- it's just single file that contains everything, so the full environment with various scenes are game like, if i needed a shot i move the chars. to the scene place, so taking the chars to origin is very hard if not impossible.

marc dion commented

2015-03-13 19:11:08 +01:00

This comment was removed by @MarcClintDion

*This comment was removed by @MarcClintDion*

Sergey Sharybin commented

2015-03-18 10:09:11 +01:00

Developer information:
The issue is actually coming from the way how ray bounce is happening: it is using ray_offset() in order to avoid self-intersection. This function will push ray along the face normal by a small value. This small value is different for different axis and actually depends on magnitude of the original coordinate. In this case ray is getting pushed a bit more along Y axis than along X and Z axis. This makes ray to be moved into the surface itself, causing light artifacts.

I'm not really sure how to solve this with current approach to ray bounce, but the idea i was testing is to avoid having ray_offset() all together and perform "near clip" check in triangle intersection code. Here's a really quick patch which demonstrates the idea: tnear.patch. It is only done for triangles, motion triangles and hair would give artifacts with it.

This approach could make it simplier to deal with #43865, increasing ray_tnear for a huge values of det would avoid false-positive intersections.

Developer information: The issue is actually coming from the way how ray bounce is happening: it is using `ray_offset()` in order to avoid self-intersection. This function will push ray along the face normal by a small value. This small value is different for different axis and actually depends on magnitude of the original coordinate. In this case ray is getting pushed a bit more along Y axis than along X and Z axis. This makes ray to be moved into the surface itself, causing light artifacts. I'm not really sure how to solve this with current approach to ray bounce, but the idea i was testing is to avoid having `ray_offset()` all together and perform "near clip" check in triangle intersection code. Here's a really quick patch which demonstrates the idea: [tnear.patch](https://archive.blender.org/developer/F152649/tnear.patch). It is only done for triangles, motion triangles and hair would give artifacts with it. This approach could make it simplier to deal with #43865, increasing `ray_tnear` for a huge values of `det` would avoid false-positive intersections.

marc dion commented

2015-03-18 12:29:19 +01:00

This comment was removed by @MarcClintDion

*This comment was removed by @MarcClintDion*

Sergey Sharybin commented

2015-03-18 12:38:40 +01:00

The patch i've attached only to show an idea, i didn't mention it fixes anything. It still needs quite some work to be done.

marc dion commented

2015-03-18 18:22:06 +01:00

This comment was removed by @MarcClintDion

*This comment was removed by @MarcClintDion*

Jaroslav Novotny commented

2015-03-26 13:35:02 +01:00

Added subscriber: @jerryno

Jaroslav Novotny commented

2015-03-26 13:35:02 +01:00

A related bug report: #41073.

A related bug report: [#41073](https://developer.blender.org/T41073).

Sergey Sharybin commented

2015-04-08 19:02:33 +02:00

Moving to a TODO since it's known floating point issue which existed in all releases.

Yousef Harfoush commented

2015-04-08 23:29:07 +02:00

Added subscriber: @Sergey

Yousef Harfoush commented

2015-04-08 23:29:07 +02:00

@Sergey: do i need to redo my animation now! or is there a work around that can overcome this till it is fixed, frankly a TODO task means years+ of waiting, thank you.

Sergey Sharybin commented

2015-04-13 12:55:53 +02:00

it is not a trivial issue to fix in a general case without causing render slowdown. TODO does not mean years+ of waiting, there's WIP patch which you can potentially use already.

Non-code workaround for you would be to parent your scene to an empty and move it closer to the scene origin.

it is not a trivial issue to fix in a general case without causing render slowdown. TODO does not mean years+ of waiting, there's WIP patch which you can potentially use already. Non-code workaround for you would be to parent your scene to an empty and move it closer to the scene origin.

Yousef Harfoush commented

2015-04-13 18:49:27 +02:00

ok i tried the batch you've made, it works! i didn't try it before because of the artifacts that @MarcClintDion mentioned, which i didn't find any of it ! but maybe it would exist in some extreme situation.

one thing arises is that the viewport is darker than the final render (or it turns smoothing off), here is a test:

also i didn't notice a slowdown in my case, notice the render time for viewport and render.

thank you.

ok i tried the batch you've made, it works! i didn't try it before because of the artifacts that @MarcClintDion mentioned, which i didn't find any of it ! but maybe it would exist in some extreme situation. one thing arises is that the viewport is darker than the final render (or it turns smoothing off), here is a test: ![viewVSf12.png](https://archive.blender.org/developer/F161593/viewVSf12.png) also i didn't notice a slowdown in my case, notice the render time for viewport and render. thank you.

Sergey Sharybin commented

2015-04-13 20:54:44 +02:00

@bat3a, the issue mentioned by @MarcClintDion are happening with really insane coordinates, which are totally stressing single precision floating point arithmetic. Those cases are quite tricky to solve in general case and requires some black magic (which would still fail in certain circumstances btw).

The viewport issues are rather interesting, i'll have a look into them ASAP.

@bat3a, the issue mentioned by @MarcClintDion are happening with really insane coordinates, which are totally stressing single precision floating point arithmetic. Those cases are quite tricky to solve in general case and requires some black magic (which would still fail in certain circumstances btw). The viewport issues are rather interesting, i'll have a look into them ASAP.

marc dion commented

2015-04-14 07:18:55 +02:00

This comment was removed by @MarcClintDion

*This comment was removed by @MarcClintDion*

Yousef Harfoush commented

2016-02-01 21:18:11 +01:00

hi
this patch is not applicable to latest git, i would appreciate if someone updates it cause the problem still exist.

thank you.

hi this patch is not applicable to latest git, i would appreciate if someone updates it cause the problem still exist. thank you.

Yousef Harfoush commented

2016-02-05 16:53:44 +01:00

anyone could update this thank you.

Sergey Sharybin commented

2017-03-23 10:05:00 +01:00

Added subscriber: @midan-3

daniel commented

2017-05-23 18:22:04 +02:00

the problem still occurs in latest build 9b29233

the problem still occurs in latest build 9b29233

Sergey Sharybin commented

2017-10-05 12:22:53 +02:00

Added subscribers: @ManuJarvinen, @VukGardasevic

marc dion commented

2017-10-05 12:48:07 +02:00

This comment was removed by @MarcClintDion

*This comment was removed by @MarcClintDion*

Brecht Van Lommel commented

2018-03-15 02:50:36 +01:00

Added subscribers: @LukaszDebita, @brecht, @Foaly

Sergey Sharybin removed their assignment 2020-03-13 16:20:51 +01:00

Sergey Sharybin commented

2020-03-13 16:20:51 +01:00

There is D6250 which addresses this issue.

There is [D6250](https://archive.blender.org/developer/D6250) which addresses this issue.

Evan Wilson commented

2020-08-11 02:40:57 +02:00

Added subscribers: @BlakeF24, @EAW, @vasiln, @zaster

Evan Wilson commented

2020-11-14 19:29:58 +01:00

Added subscriber: @MOSESNES

Nathan Vasil commented

2020-11-14 22:50:53 +01:00

In #43835#464224, @MarcClintDion wrote:
If behind the scenes, Blender were to move the entire scene using the inverse of the camera transform instead of moving the camera itself, then visible close-up models would never be far from the origin. Now round-off/precision errors would likely be mostly eliminated.

In other words, why is Cycles performing any calculations in world space? Wouldn't camera space be a more appropriate space for these operations? Perhaps offset by some fraction of far clip?

> In #43835#464224, @MarcClintDion wrote: > If behind the scenes, Blender were to move the entire scene using the inverse of the camera transform instead of moving the camera itself, then visible close-up models would never be far from the origin. Now round-off/precision errors would likely be mostly eliminated. In other words, why is Cycles performing any calculations in world space? Wouldn't camera space be a more appropriate space for these operations? Perhaps offset by some fraction of far clip?

Evan Wilson commented

2021-01-08 00:58:13 +01:00

Added subscribers: @B_Engstler, @constantin.kormann

Philipp Oeser changed title from ~~strange cracks appear on model~~ to ray offsetting giving precission problems / render artifacts / cracks on far away geometry

2021-02-01 17:19:50 +01:00

Philipp Oeser commented

2021-02-01 17:20:53 +01:00

Added subscribers: @imrevarga, @lichtwerk

Imre Varga commented

2021-02-05 08:24:21 +01:00

So looks like we have to live with that.

By the way, I got around my problem on hand by having the cyclist cycle in place and moving the landscape. This is the equivalent to (marcclintdion) 's proposal.

So looks like we have to live with that. By the way, I got around my problem on hand by having the cyclist cycle in place and moving the landscape. This is the equivalent to (marcclintdion) 's proposal.

Philipp Oeser commented

2021-04-08 15:55:09 +02:00

Added subscriber: @IPv6

Zijun Zhou commented

2021-04-12 02:13:13 +02:00

Added subscriber: @Eary

Zijun Zhou commented

2021-04-12 02:13:13 +02:00

Don't know if this is the same issue, but I am having a similar problem, a large scale scene with a character far away from world origin

This eyebrow's material has a Alpha value of 0, so it should have been completely transparent. It works fine at the world's origin, but does not work at all at where the character should be. This is a serious issue, hope it gets fixed soon.

Don't know if this is the same issue, but I am having a similar problem, a large scale scene with a character far away from world origin ![image.png](https://archive.blender.org/developer/F9929886/image.png) This eyebrow's material has a Alpha value of 0, so it should have been completely transparent. It works fine at the world's origin, but does not work at all at where the character should be. This is a serious issue, hope it gets fixed soon.

Philipp Oeser commented

2021-04-19 09:32:47 +02:00

Added subscriber: @imdjs

Philipp Oeser commented

2021-06-01 17:14:58 +02:00

Added subscriber: @roman-13

Germano Cavalcante commented

2021-09-28 21:05:37 +02:00

Added subscribers: @etufo2, @ktdfly

ML commented

2021-11-26 02:35:00 +01:00

Added subscriber: @MarcelLegindi

Brecht Van Lommel commented

2021-12-14 17:18:11 +01:00

Added subscribers: @3di, @deadpin

marc dion commented

2021-12-14 20:24:06 +01:00

Removed subscriber: @MarcClintDion

Alaska commented

2021-12-14 21:09:29 +01:00

Added subscribers: @sharukh345, @leesonw, @Alaska

Alaska commented

2021-12-17 21:36:54 +01:00

Added subscriber: @binke

Alaska commented

2021-12-17 23:06:44 +01:00

Added subscriber: @A-T

blender-admin commented

2022-01-13 17:20:50 +01:00

This issue was referenced by blender/cycles@e38b69de0f

This issue was referenced by blender/cycles@e38b69de0f5d47bed2784ba63c71a0cba4eda7ec

blender-admin commented

2022-01-13 17:20:50 +01:00

This issue was referenced by 74afc86d4b

This issue was referenced by 74afc86d4bf1a559e5b7a0cf5cea29cb508a3e99

Alaska commented

2022-01-13 22:19:09 +01:00

Added subscriber: @animation.entertainmenttv

b5327157 commented

2022-01-21 17:59:32 +01:00

Added subscriber: @b5327157

Brecht Van Lommel commented

2022-01-26 17:55:33 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Brecht Van Lommel closed this issue

2022-01-26 17:55:33 +01:00

Brecht Van Lommel self-assigned this 2022-01-26 17:55:33 +01:00

Brecht Van Lommel commented

2022-01-26 17:55:33 +01:00

This should be much improved now with the latest changes:

Remove small ray offsets that were used to avoid self intersection, and leave
that to the newly added primitive object/prim comparison. These changes together
significantly reduce artifacts on small, large or far away objects.

The balance here is that overlapping primitives are not handled well and should
be avoided (though this was already an issue). The upside is that this is
something a user has control over, whereas the other artifacts had no good
manual solution in many cases.

There is a known issue where the Blender particle system generates overlapping
objects and in turn leads to render differences between CPU and GPU. This will
be addressed separately.

However it doesn't mean all artifacts are necessarily generated, there will always be some larger/smaller value that causes problems. If any remaining issues are still considered bugs we'll have to check case by case.

This should be much improved now with the latest changes: ``` Remove small ray offsets that were used to avoid self intersection, and leave that to the newly added primitive object/prim comparison. These changes together significantly reduce artifacts on small, large or far away objects. The balance here is that overlapping primitives are not handled well and should be avoided (though this was already an issue). The upside is that this is something a user has control over, whereas the other artifacts had no good manual solution in many cases. There is a known issue where the Blender particle system generates overlapping objects and in turn leads to render differences between CPU and GPU. This will be addressed separately. ``` However it doesn't mean all artifacts are necessarily generated, there will always be some larger/smaller value that causes problems. If any remaining issues are still considered bugs we'll have to check case by case.

michael campbell commented

2022-01-26 18:36:59 +01:00

For rendering, could the precision centre be the camera instead of world 0? That way you'd never get perceivable precision artefacts (only on very distant stuff).

Brecht Van Lommel commented

2022-01-26 18:48:59 +01:00

That way you'd never get perceivable precision artefacts (only on very distant stuff).

This assumption is not correct, there are many artifacts that would not be helped by this.

And besides that, there are other trade-offs related to this as well. Issues with frame-to-frame coherence in animation, impossible to efficiently support for interactive viewport render, additional overhead in texturing/shading, etc.

> That way you'd never get perceivable precision artefacts (only on very distant stuff). This assumption is not correct, there are many artifacts that would not be helped by this. And besides that, there are other trade-offs related to this as well. Issues with frame-to-frame coherence in animation, impossible to efficiently support for interactive viewport render, additional overhead in texturing/shading, etc.

michael campbell commented

2022-01-26 18:55:14 +01:00

I'll have to give it a whirl by setting the entire scene as a collection instance and move that horizontally and the camera vertically only. I never get perceivable geometry changes with adaptive displacement, so I reckon it'll be the only solution for unreal engine size worlds.

Animation Entertainment commented

2022-01-27 07:38:38 +01:00

I still have the same problem even in Blender 3.0.1. Nothing has been improved on my end. This problem is persistent.

I still have the same problem even in Blender 3.0.1. Nothing has been improved on my end. This problem is persistent. ![Blender Render With Error.png](https://archive.blender.org/developer/F12826937/Blender_Render_With_Error.png) ![Blender Render Without Error.png](https://archive.blender.org/developer/F12826936/Blender_Render_Without_Error.png)

Philipp Oeser commented

2022-01-27 09:23:31 +01:00

In #43835#1295700, @animation.entertainmenttv wrote:
I still have the same problem even in Blender 3.0.1. Nothing has been improved on my end. This problem is persistent.

This will only be in 3.1, not 3.0.1

> In #43835#1295700, @animation.entertainmenttv wrote: > I still have the same problem even in Blender 3.0.1. Nothing has been improved on my end. This problem is persistent. ![Blender Render With Error.png](https://archive.blender.org/developer/F12826937/Blender_Render_With_Error.png) > > ![Blender Render Without Error.png](https://archive.blender.org/developer/F12826936/Blender_Render_Without_Error.png) This will only be in 3.1, not 3.0.1

Jan Kadeřábek commented

2022-02-23 09:34:10 +01:00

Added subscriber: @JanKaderabek

Alex Ducos commented

2022-03-10 00:02:50 +01:00

Added subscriber: @Alex-Ducos

Alex Ducos commented

2022-03-10 00:23:14 +01:00

My scene has this issue as well! I am, indeed, pretty far from the origin. (By necessity - this is a large scene!)

^ current distance from the scene origin ^

Setting location to the scene origin DOES remove artifacts.

Seeing as this issue cannot be avoided for large scenes, within CYCLES (in RECENT builds) I would actually request that we re-open this "closed, resolved" case! (Seeing as this is a TOTALLY nasty issue, which can't always be hacked around!!)

Anyone who should see this comment, PLEASE - help me to know how to notify a developer! (this is the first time I have done anything which smells even remotely of a bug report - so I have no idea what I'm doing!)

THANK YOU!!!

![image.png](https://archive.blender.org/developer/F12915448/image.png) My scene has this issue as well! I am, indeed, pretty far from the origin. (By necessity - this is a large scene!) ![image.png](https://archive.blender.org/developer/F12915673/image.png) *^ current distance from the scene origin ^* Setting location to the scene origin DOES remove artifacts. ![image.png](https://archive.blender.org/developer/F12916192/image.png) ![image.png](https://archive.blender.org/developer/F12916364/image.png) Seeing as this issue cannot be avoided for large scenes, within CYCLES (in RECENT builds) I would actually request that we re-open this "closed, resolved" case! (Seeing as this is a TOTALLY nasty issue, which can't always be hacked around!!) Anyone who should see this comment, PLEASE - help me to know how to notify a developer! (this is the first time I have done anything which smells even remotely of a bug report - so I have no idea what I'm doing!) *THANK YOU!!!*

Alaska commented

2022-03-10 03:47:08 +01:00

@Alex-Ducos It's probably best if you make a new bug report. This can be done by:

Opening Blender.
Selecting from the top of Blender Help -> Report a bug and a form will open in your web browser.
Fill out all the information related to the bug you're experiencing (and include a .blend file if you can). The triaging team will then take a look at your bug report.

@Alex-Ducos It's probably best if you make a new bug report. This can be done by: 1. Opening Blender. 2. Selecting from the top of Blender `Help -> Report a bug` and a form will open in your web browser. 3. Fill out all the information related to the bug you're experiencing (and include a .blend file if you can). The triaging team will then take a look at your bug report.

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