Strange view artifacts with large scale object

oct · December 20, 2019, 9:24pm

Blender v2.81.16

I noticed strange artifacts in viewport when I imported large STL objects. 1st I thought something wrong with STL file. After some messing around, I think it’s a bug.

Screenshot below is the default cube scaled up 24x with face orientation overlay.

face orientation off, MatCap

scale at 1, artifact is barely noticeable.

omgold · December 22, 2019, 8:04am

Can you upload the blend file and stl file these screenshots are from?

oct · December 22, 2019, 4:38pm

Imported STL, overlay face orientation on

same obj but scaled down, no artifacts.

imported STL.blend (879.7 KB) Inner gear-1.STL (59.8 KB)

init_pixel · December 22, 2019, 4:59pm

Looks like textbook z-fighting.

omgold · December 22, 2019, 5:42pm

@init_pixel is right, z-fighting. Not sure how the z-depth is stored internally, but it seems the scaling depends on the view clipping settings. I notice when I increase Clip Start from 0.001 to 0.1 the issue is gone. It also is gone in orthographic view.