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Unreal exports Sideways Models to C4D


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Anyone Notice that C4D gets Models Flipped when exporting FBXs out of Unreal and it sometimes reverses them? As a work around I export the fbx from Unreal and into maya or Max then re export an fbx that I open in C4D that has an Axis that is correct. Any other work arounds ?

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13 minutes ago, Jeremy Gullotto said:

Anyone Notice that C4D gets Models Flipped when exporting FBXs out of Unreal and it sometimes reverses them? As a work around I export the fbx from Unreal and into maya or Max then re export an fbx that I open in C4D that has an Axis that is correct. Any other work arounds ?

 

Unreal uses Z-Up for its coordinate system. But C4D users Y-Up. That is why your model will be flipped. I haven't looked yet, but there may be an option when exporting out of Unreal to convert the coordinate system to Y-Up?

 

Otherwise from the C4D dialog that appears when you import your FBX file, change the Geometry->Up-Axis to be "Z-Axis".

 

Not sure why your files are reversed though. They should come in fine. But you could try checking the Flip-Z-Axis option as well to see if that helps.

 

 

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I tried tried this when I  first noticed this problem, but it will only flip your model upside down and never right side up. try it.  I also try the force x option when exporting from unreal and these options and still couldn't get the right side up. Ive also had issues where the model imports in negative /inside out and reversed normals.

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  • Solution

Having done this a lot, I know the solution.

Import to Cinema with default settings.

Then export the FBX from Cinema again, with 'Z Up'

Then re-import this new fbx with default settings & it will be correct.

Don't ask me why this is different to just importing with z-up but it is. It works every time.

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2 hours ago, Jeremy Gullotto said:

KUDOS! LOL, I knew this would work as soon as I read "export with Z up". This is the only option I never thought to try. 

 

Thanks!

No problem. Wait until you try & import Alembic Geometry Caches from Cinema to Unreal. You have to un-parent the geometry from the hierarchy in Cinema & import to Unreal using the 3DS Max preset. This is the only way it comes in at the right world coordinates & orientation.

 

I feel by this point I know almost every bastard foible of Unreal's fussy pipeline.

 

One saving grace is we do  have at least 3 routes in & out - FBX, Alembic & Datasmith are all very valid & have advantages for different situations.

 

A rule I found for both skeletal animation via fbx & geometry cache animation via alembic is that unsupported object types in the hierarchy, such as nulls & splines are not only ignored but mess up the global positioning & rotation.

 

For characters & vehicles, we developed a system of having 2 seperate hierarchies - an 'Animation Rig' that stays in Cinema & consists of whatever objects, constraints, IK etc & a 'bind rig' which is just joints & meshes, constrained back to the 'animation rig' via psr constraints. To be fair, I think this is more or less the pipeline of forever in games etc. But coming from a film & TV background with a somewhat lesser supported application, we ended up re-inventing the wheel a bit at times.

 

We bake the animation as PSR keys to the 'bind rig' prior to export (we have python scripts to speed this up) & export only the 'bind rig' to Unreal.

 

There are other quirks. I believe (but not 100% sure) that the only thing that doesn't work via the FBX re-export trick from Unreal -> Cinema is cameras. If I remember rightly, you can enter a 90 deg offset in one of the camera's frozen coord axis in Cinema to fix FBX cameras coming in via default settings.

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  • 1 year later...
Quote

Having done this a lot, I know the solution.

Import to Cinema with default settings.

Then export the FBX from Cinema again, with 'Z Up'

Then re-import this new fbx with default settings & it will be correct.

Don't ask me why this is different to just importing with z-up but it is. It works every time.

No matter what combination of the C4D importer you choose, it never gets you the character pointing head upwards. I also tried the FBX export forcing option in UE export. This is exactly what still happens in Cinema 2023.2.2 with UE 5.3 mannequin - and this solution works. I still need to find out, how to correctly export back to UE.

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In 2024 this is resolved, the FBX import had been re-jigged & you can now choose -Z on the import to have stuff come in the right way up.

HOWEVER, there is a new bug where skeletal mesh exports via fbx won't open in Unreal, so the exports the other way need to go from Cinema 2023.2.2.

I've reported the bug so hopefully there will be a fix soon.

Otherwise, I haven't had any need to change from the default when exporting from Cinema to Unreal.

One caveat is that in the case of skeletal meshes, Unreal will ignore any objects other than joints & meshes in the hierarchy & therefore mess up rotations if they are present. You can use the 'replace with ...' command from the tools menu to substitute nulls & splines etc with joints while retaining animation. This lets you get those animated hierarchies into Unreal ocrrectly Although the ideal is to design your rigs with a seperate bind rig of just joints & meshes.

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