Broken geometry when importing to Unreal Engine

Development Pipeline & Plugins
,
1

I converted a tm file from 2022.2.3 to 2023.1 and tried exporting it to ue5.1 using new datasmith exporter and geometry was broken. I made a simple demonstration.

I created identical scenes in tm 2022.2.3 and 2023.1, also I converted from 2022.2.3 to 2023.1.

All three files have the same look in tm.

Twinmotion 2022.2.3
Twinmotion 2022.2.3720×285 75.9 KB
Twinmotion 2023.1
Twinmotion 2023.1720×286 73 KB
Twinmotion 2023.1 converted from 2022.2.3
Twinmotion 2023.1 converted from 2022.2.3720×285 76.6 KB

Now when I try importing them to ue5.1 I get the following:

  • TM 2022.2.3 when imported to ue doesn't include some materials like in this example. This was done using old datasmith plugin for UE.

Twinmotion 2022.2.3 imported to UE
Twinmotion 2022.2.3 imported to UE720×387 100 KB

  • TM 2023.1 when imported to ue looks fine. Imported using new datasmith.

Twinmotion 2023.1 imported to UE
Twinmotion 2023.1 imported to UE720×389 97.8 KB

  • TM 2023.1 that was converted from 2022.2.3 when imported to ue breaks geometry. Imported using new datasmith.

Twinmotion 2023.1 converted from 2022.2.3 imported to UE
Twinmotion 2023.1 converted from 2022.2.3 imported to UE720×390 99.3 KB

Even though all twinmotion files look the same, their imports to UE don't.

Old datasmith doesn't support some materials, so I was hoping to convert to new version and then export using new datasmith that does support but seems like converting from 2022.2.3 to 2023.1 breaks something that you can't see in twinmotion itself. Recreating whole projects in 2023.1 doesn't seem like a good option. If anyone has any idea what's going on I would appreciate it.

Thanks.

2

It looks like the cushions on the seat may have their faces reversed. Try selecting Two Sided Material on the material in the last image. Most likely the cushions will show then.

3

Sorry I forgot to update the post, but I did find what's wrong.

It seems normal map conversion is a problem. I'm not sure how normal map is stored and why there are yellowish and blueish normal maps.

Here you can see how TM 2023.1 shows normal map in a file created by it.

2023.1 TM normal map
2023.1 TM normal map720×405 78 KB
And here is how it looks in a file converted from 2022.2.3 opened in 2023.1

2022.2.3-2023.1 TM normal map
2022.2.3-2023.1 TM normal map720×405 81.2 KB
And after exporting these files as datasmith files and importing them into UE you get the following.

File created in 2023.1 converts the yellowish normal to bluish that UE supports

2023.1 UE normal map
2023.1 UE normal map720×344 75.2 KB
While file converted from 2022.2.3 to 2023.1 turns bluish normal map into orange and that breaks the look.

2022.2.3-2023.1 UE normal map
2022.2.3-2023.1 UE normal map720×335 77 KB

I'm guessing there is a bug somewhere in conversion from one file version to another. Datasmith probably expects yellowish normal from TM and converts it into bluish, but when it get's bluish it turns it into orange.

4

Hello ,

Thank you for the follow-up and details and have this bug TM-10848 documented for our team. We expect to have a fix for this in the next release. Please contact us directly if you find any further issues:

https://twinmotionhelp.epicgames.com/s/case-community-page

Kind regards,

Vincent B.