Developer Notes

The only way to have the same DCC value for UVs in UE4 is to tick the build settings option "Use Full Precision UVs" in the staticmesh editor under the LOD 0 see the attach picture. We reduce the precision to reduce the size of the runtime data. If a model has an issue with the compression, the user have to turn on the precision but the asset will then use more resources.

Description

The UV layout of a Mesh is altered slightly when exported from the engine. It becomes more noticeable on objects as their UV Islands shrink in size. Given a default full 0-1 unwrap it looks like this does not occur.

This was tested using Maya 2014 and Max 2013.

Reproduced in Binary 4.7 Preview 3

Reproduced in Promotable-CL-2408355

Steps to Reproduce

1. Open QA Game Editor
2. Import Attached Test_Box_UV.fbx
3. Export the newly Imported Mesh as another FBX (included as Test_Box_UV_fromUE4.fbx)
4. Open Maya or Max
5. Import Test_Box_UV.fbx and fbx from Step 3 (or Test_Box_UV_fromUE4.FBX)
6. Open UV Editor

RESULTS: UVs are slightly offset

EXPECTED: UVs should be identical

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Non-Issue
ComponentTools - Import
Affects Versions4.6.14.10.24.114.12
CreatedJan 19, 2015
ResolvedDec 6, 2016
UpdatedApr 27, 2018