LOD meshes Import with 90° rotation?

Hey Guys,

I’m having a weird Issue when Importing LODs. When I import an LOD for a mesh using the mesh viewer/Content browser method, it seems like the LOD is rotated 90° on Y for some strange reason. Can anyone help? Not sure if this is a bug or something I’m missing!

This is only an issue when importing LOD meshes, the base FBX files work fine. Also I’m using FBX 2013.

I’ve attached a picture so it’s easier to understand:

After a little more investigation, it appears this only happens on meshes that have been previously saved when having no LODs.

If you’ve got a mesh with no LOD, save it, and then import an LOD into that mesh, it seems to break the system.

Is there any fix/workaround to this? It’s a big deal for us since we’re porting a Game from UE3 to UE4 and have ALL of our meshes imported with no LODs at the moment.

Cheers!

Hi JHBurton,

I’m, unfortunately, not able to reproduce this. I’ve made a simple box in 3Ds Max with some verts moved for each LOD (1 base import saved and closed the editor before opening back up to reimport the other LODs, and two lower LODs). I’m not seeing the same results.

I tested this on the 4.5.1 Launcher version and I am currently using 3Ds Max 2013.

Can you verify what version of the engine you’re currently using? Is this a SpeedTree asset or a custom created mesh? Also, are you able to setup a simple mesh and reproduce this with a new asset?

Thank you. :slight_smile:

Tim

Hey Tim,

Thanks for the quick response. I managed to replicate it once more. The issue only happens if your previously saved the mesh with no LODs, then close the editor. If you don’t close the editor it seems they work fine, but if you close the editor, next time you open it and try to import an LOD into that mesh, you get the rotation error.

I’m using 4.4.1 (although I’m downloading 4.5 now to test it there) and Maya 2014 (with fbx 2013) and the mesh is a custom made one, not a SpeedTree. I managed to reproduce it with a simple box and basically doing what you did hehe.

I’ll do a test with 4.5.1 as soon as it downloads and let you know how it goes.

Thanks!

Hey Tim,

I managed to replicate it in 4.5.1 as well - Didn’t do anything different.
EDIT: Here is a video of the bug. Replicated in UE4 4.5.1 - FBX 2013

Hi ,

Thanks for the video to demonstrate. I was initially not able to reproduce this since the meshes I was using were made in 3Ds Max. I did get some test assets from Maya to use and did get the error.

I’ve submitted a bug report for this issue (UE-5041).

Once a fix has been submitted I will update this post when I can verify it.

Thank you!

Tim

Still broken in UE 4.7.2

i can confirm its doing this in 4.7.3
i tried rotating my LOD prop 90º forward to compensate, and it imported that way. Seems like the Maya standard Y-up is playing havoc with unreal’s Z-up

I also have this problem in UE 7.4.4. :frowning:

It is still happening in UE 4.7.5… the workaround is to rotate the asset before importing to UE4, compensating the rotation error!

Same here, still have this issue.

It does sound like some kind of axis conversion problem. Solution is to export your LODs Z-up, even if your base mesh works Y-up.
(Source: exporting from Max to 4.6)

Just encountered this in 4.8.2 OS X 10.10.4. For me the issue was I apply a -90yaw when importing my normal Static Mesh (coming from Blender). When i then import the LOD1 mesh there is no way to apply this same import rotation to the LOD mesh, only scale (in the build settings). I still would be easier if UE4 could introdice support for reading _LOD0, _LOD1 etc in the FBX file or at the very least allow us to assign a previously imported Static or Skeletal mesh UAsset.

I can confirm that the following procedure breaks LOD1 assets.

  • import any mesh for the base LOD
  • save, quit, open the editor again
  • import LOD1 for the mesh (you can use the same FBX as the LOD0)
  • enjoy flat-shaded, rotated mesh

UE 4.9 release.

How is it possible that a bug this huge has been unresolved and even unreproduced for almost a year ?

I got a coder friend of mine to do a fix for this

https://github.com/EpicGames/UnrealEngine/pull/1413

It’s waiting to be looked at if possible?

I can confirm as well on 4.9 that this is still happening.

Having to do LOD’s on 100+ meshes that are already in engine is going to be an incredible time sink and greatly slows production since the only way to fix it is to do a fresh import LOD0 and set everything up at once.

Please Fix - Thanks.

I fixed this and my PR has been accepted by Epic, so it should definitely be fixed in 4.11, it may be in 4.10, but I’m not sure if I made the cut off before branch or if it has been integrated across to the 4.10 branch. For reference, it is this change:

https://github.com/EpicGames/UnrealEngine/pull/1413

Tommy.

I’m having this problem with 4.10.1 and still not fixed!?!

Hi guys Just found a quick fix. Just click on reimport and then u can import the LOD

Hi, i’m facing the same problem on 4.25 too.