What happened to my mesh?

[JohanGrip]

I drone-scanned an area and created an obj from that scan, I imported it to Blender and used the smooth tool in sculpt mode to smooth the mesh where it was a bit jagged. Then I added textures and trees etc. When I was finished with the project I packed the resources (and moved it to an external HD). Today I needed to work on the project again, but when I opened it the areas that I had smoothed looked jagged again, but the mesh was smooth. It looks good in sculpt mode, but not in object mode etc. or when rendered. See attached images.

Does anyone know the reason for this, and how to solve it? All help appreciated.

[grant.r.brown]

Hard to tell without seeing the mesh topology, but you can try the following:

1. Edit mode > alt+N > reset vectors
2. Does it have a multiresolution modifier? Up the viewport resolution to the same as the sculpt and render.
3. Does the material have displacement? Set the displacement scale to something like 0.03 and see if that removes the black bits.

[JohanGrip]

Thank you for replying. The mesh is smooth as in the left image. The original obj had jagged parts (due to drone scanning imperfection) as seen on the other images, but now it’s like “digitaly jagged”.
Tried alt+N, didn’t work. It has no multiresolution modifier or displacement.

[digitvisions]

Hi, without seen the wireframe it is hard to tell but it dose look like there is another mesh underneath?

[JohanGrip]

There’s no other mesh. See attached image for wireframes.

[grant.r.brown]

Have the color inputs of the texture reverted to sRGB for the normal etc.?

[colkai]

Have you checked for custom normals?

[JohanGrip]

I doesn’t seem to have anything to do with the texture. I tried different textures and no texture, but the artifact (or what it is) is still there. I have removed all vertex groups and particle systems also. So now it’s just a mesh with a Principled BSDF (tried to change settings in this but it didn’t help).
It only disappear when I change to Sculpt Mode (but change back when I exit Sculpt mode).

[digitvisions]

If you look closely you can actually see the lines of the fault.(or is it an illusion)

[JohanGrip]

yeah, you’re right. haven’t seen that till now. But it IS also an illusion, when I orbit around those areas the mesh is flat and smooth.

[digitvisions]

Can you share the file? i am intrigued by it.

[JohanGrip]

Sure, see if you can download it from my dropbox:
https://www.dropbox.com/s/kl6rrywvmblgk9r/kevinge_CFS.blend?dl=0

[RSEhlers]

I doubt anyone would download a 1.4 GB file just to test it. Perhaps you could select a small slice of that mesh and save it as an FBX or Obj file, then we can get an idea about what is going on…

[JohanGrip]

Good point Here’s a link to fbx:
https://www.dropbox.com/scl/fi/789bvxzo8jfwn2dbpim3z/kevinge_part.fbx?rlkey=skvbtwru6uq79rnie5zdwjs61&dl=0

[digitvisions]

What i see is the mesh distorted:

[Andreal (Andrzej)]

Uncheck custom normals while importing fbx:
flat shading:

smooth shading:

No strange lines.

[lqppro (Luis Quintana)]

No need to reimport, just clear Split Normals Data:

And its fixed.

In your original .blend file.

[digitvisions]

It’s easy when you know how.

[JohanGrip]

Wow! That really worked! Thank you!

[JohanGrip]

I tried to open the project in the version it was first made in (3.5) instead of my current 4.2, and then it looked good, so different blender versions seemed to be the reason for the issue.
Thanks all for trying