Keep UV data for each frame after import

[Alembic Fan]

Hi,
I want to use Alembic to change my pipeline for a very specific approach in Unreal.

I have thousands of frames, each with individual UV's and individual Textures for each frame. After importing them into Maya and exporting the sequence, I want to use a video texture (made from an image sequence of the individual textures) in Unreal to texturize the alembic. I did this successfully, but I noticed that only the UV of the OBJ of the very first frame is applied to the alembic, which of course results in each following frame of the video texture being wrong. Reading through all the topics in this forum concerning UV's, I learned that the UV information should be stored for each frame, but might be lost when importing the alembic. Is there any solution to my problem?

Thank you very much in advance for any replies and thank you so much for your work on Alembic!

[Lucas Miller]

Animated UVs should currently be supported by the Maya Alembic importer.

If it's not working, do you have a simple example you can share?

Lucas

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[ourotu...@gmail.com]

When you import into unreal try looking under the mesh setting or import settings for "full percision UVs" and make sure it is checked. When you import your obj into maya and before you export as alembic can you confirm that the UVs are working as they should? If they are correct on import then carefully check your alembic export settings. This might help. Check the parts about UV writing (https://knowledge.autodesk.com/support/maya/learn-explore/caas/CloudHelp/cloudhelp/2016/ENU/Maya/files/GUID-6C9504CD-9107-4DA2-B618-CAA9045906D4-htm.html)

[Alembic Fan]

Since I'm currently not at the office, I can't send you my project, but I'll explain how I set it up: 

To make sure it's not a specific problem with my meshes, I created a cube and exported 25 frames with one UV and  25 with an altered one. I combined these into a 50 frame sequence, which I exported as an alembic. I tried different settings under advanced settings (including "write UVs") but when I either reimported the abc into Maya or imported it into Unreal, the UV wouldn't switch after 25 Frames. I didn't try the Import setting full precision UVs as mentioned in the post below, but it didn't work in Maya either. Did I miss something?

[Alembic Fan]

@ outrotu: Except for "full precision UVs" I tried reimporting the sequence into Maya and even there the UVs didn't Change. I already checked the Settings for UV writing and I can confirm the UVs are working before exporting them. I can't be certain though if the UV data already gets lost during the export or the Import, since the only way for me to check is importing.

[Alembic Fan]

Unfortunately, I can't find the option "full precision UVs" in the import options (using 4.19 and 4.18). I tried Unity and the issue remains. Is there an export option under advanced options in Maya except for UV write which would need to be checked? Thank you!

On Tuesday, May 29, 2018 at 7:01:03 PM UTC+2, ourotu...@gmail.com wrote:

[Lucas Miller]

Yes, the UV write option should be all you need.

Do you have a simple example that you can share where you thought you
wrote out the animated UVs?

I just did a simple test with a cube and was able to successfully
animate it in Maya, but it would be good to double check in case there
was an issue with the version you are using.

Lucas

[Alembic Fan]

Thank you for your replies. I managed to fix it! :)

Since I'm not 100% sure which of these steps fixed the problem, I'm just going to list my settings in case someone else will stumble across the same problem:

After Maya reset my plugins I had to reactivate them to regain the alembic export option. I selected these plugins: AbcBullet,AbcExport,AbcImportm animImportExport. In the Export options I made sure to have the right amount of frames in start-/endframe and only selected UV Write and Ogawa in the advanced options tab. After that, the UVs worked perfectly!

Unfortunately when I run the abc in unreal with a video texture, the frames are out of sync and I need to figure out a way to get them to match. Since I don't understand a lot of aspects about alembic yet, I wonder if there is a way to assign a texture per frame in maya and to somehow include it in the alembic, without it acting only as a container, which after import would just create thousands of materials in my Unreal-project...

[ourotu...@gmail.com]

The way I planned on doing my UVs was by splitting the UV space into a grid with each mesh in the simulation having its own spot in the grid. Then I would use a sprite sheet like this (https://cdna.artstation.com/p/assets/images/images/003/296/928/large/inimai-ganesan-volcano-smoke-spritesheet.jpg?1472136286)

Depending on how many meshes you have this might not be viable but I thought it was worth mentioning.

Do you have the same playrate set on your video texture as you do on your cache? Are they the same amount of frames?