Unreal 4.16 New Uv channels not added on reimport

Development Asset Creation
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Hey

I’m currently dealing with about FBX assets that need to be Uv’d an reimported into Unreal. Unreal doesn’t seem to read the new Uv channels on re’import, in my case two new ones pr. asset. They do import if the asset is imported clean, meaning if I change the name and import it as a “new” asset Unreal reads them just fine.

Is there a known workaround for this bug?

b.r.

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So I found a workaround for this issue.

First of all the problem seems to lie in the fact that using the “save” button in the static mesh preview doesn’t actually save changes made to the settings. To “fully” save the settings they need to be changed, the preview window needs to be closed and you need to accept saving the changes in the warning window that pops up (do you want to save the changes etc.)

Here are the steps I took to ‘fix’ this issue:

  1. In your 3D software make sure you have all the channels you need. In my case I have a “texture” channel and a “mask channel”. In addition I copy my mask channel and rename it “Lightmap”. Now i have three channels. Export the asset. Make sure your third channel isn’t empty, otherwise Unreal won’t recognize it.
  2. In Unreal, open the static mesh and uncheck the “generate lightmap UV’s” box. Close the preview window and select “yes” in the warning window. This forces the save that otherwise won’t stick.
  3. Open up the static mesh again and reimport the FBX using “asset - reimport”
  4. Check the “Generate lightmap Uv’s” box again and set the “destination Lightmap Uv’s index” to ‘2’.
  5. Close the window and again, select “yes” in the warning window.

Now you should have both of your channels from Maya/Max and the third channel should’ve been overwritten with the Lightmap Uv’s.

If you’re only using two Uv channels, i.e. for your texture and the Lightmap Unreal generates those steps shouldn’t be necessary. It only goes for three channels or more.

b.r.