Cycles shading error
Closed, InvalidPublic

Description

Rendering produces artifacts depending on the distance to the origin.

System:

Win7 64 Pro, Nvidia 1070/AMD RX 480
Blender 2.78

[IMG]http://i65.tinypic.com/r0cbck.jpg[/IMG]

Example file: https://ufile.io/39ani

Details

Type
Bug
Bastien Montagne (mont29) lowered the priority of this task from High to Incomplete.May 19 2017, 9:08 AM

Please attach (grab and drop) images and files here, not on external services. And please do not set priority yourself, this is dev task.

And check if the issue can be recreated using the latest stable 2.78c.

The problem exists with the latest official 2.78c. Thanks.

Bastien Montagne (mont29) claimed this task.

Ugh… 'artifact' camera is 12000 units away from origin!

Thanks for the report, but unfortunately this is known issue caused by limited precision of float numbers, nothing to be done here.

Dear Bastien, the artifact appears with only 400 unit away from the origin, too.
I many times worked with models far bigger than that in other packages without artifacts (think about archviz). How this could be solved in the future? Is there any plan for that?
I think it is a pretty important bug, please find a valid solution for this at least on the 2.8 releases. There should be a solution for that.

Just for the test I tried it in Max + Vray RT, no artifacts on 12000 meter distance.

I also tried Blender + Vray RT, no artifacts on 400 units.

For a real life example, now I work on an a huge interior will be longer than 400 units (and no, I do not want to scale it down as I have to able to change data with other packages using real life measures).

As it seems that other apps could handle it, IMHO it would worth to make a debate about it from developer/user side.

@Sergey Sharybin (sergey) is reference for Cycles, but pretty sure this is distance issue.

Thank you, Bastien. I hope Sergey could help in this. I work on a project for 2 years now what could be a gigantic step forward in Blender's reputation for the CGI community, but I cannot recommend it as a honest/true alternative as these kind of bugs/limitations exist. I was pretty happy when developers eliminated the CUDA texture limits (I can't tell how much that annoyed me with big scenes), now it is time IMHO to push the limits to large scale usability (viewport performance issues, GLSL speed incrase, asset management, import/export fixes, handling terminator issues with shading, etc.).

Sorry if I sound harsh sometimes; I definitely try to avoid it, but I just put all my efforts to this project and it very annoying when I face issues like this.

BTW is there any 'closed' forum for top developers who signed some kind of NDA for accessing stuff under IP? Thanks for your efforts.

This is a floating point precision issue happening in ray offset (required to avoid self-intersections) and triangle intersection. This is an error i've tried to address in D1212, but there is some bug somewhere which breaks shading.

What could also make a difference here, is to try using latest builds from buildbot. They are now using more robust (from numerical stability point of view) triangle intersection code (see rB6ea54fe9ffe2). This could help solving those artifacts.

BTW is there any 'closed' forum for top developers who signed some kind of NDA for accessing stuff under IP? Thanks for your efforts.

Blender is a free and open source project, with development mainly driven by the community. We do not encourage any closed doors support/discussions/decision. So the answer here is: no.

It also really rarely helping to get original production shot. It is always a good idea to give as simple as possible file. We don't have resources to look into production files anyway. Once you isolated the case it is matter of minutes to bring .blend file into a state which does not violate anyone's IP (distort meshes, replace textures with UV grid and so on).

In Blender community bug fixing is a 50-50 collaboration between artists and developers: artists are preparing isolated bug scenario for developers, then developers are taking over and fixing the issue from the code side.

Further discussion on this topic please direct to either our IRC or ML channels.

Hello Sergey,

I never used buildbot, I tried the last nightly build (assuming that it contains the changes; correct me, if I'm wrong)

It was the blender-2.78-6cd1d34-win64.zip from blender.org and the artifacts still appear.

Is there a way to access a more up to date version .zip file I could check with the sample file I shared? Thanks