Xgen render sequence groom incorrect (Arnold)

[ratherwilde]

Hi there,

I'm Arnold rendering a turntable of a character of mine, 4 frames rotating 90 degrees each frame. If I render the frames one at a time they are fine. If I use the render sequence button I get the below issue from the second frame onwards. The groom moves around, not just in world space but the shape changes so I assume it's the guides changing shape or something too. I've tried everything to get it fixed, it even stumped my groom friend Jesus Fernandez. I would really like to get it fixed. I've been told I could just convert it to an interactive groom but that is just sweeping the issue under the rug.

Things I've tried:

* It renders fine in redshift... no weird warping.
* Exporting Patches for Batch render
* switching between GPU and CPU rendering

* Turning the guides to curves and back again

* Turning off all modifiers to make sure it's not a rough noise or parameter in the modifier stack

* Switching between live and batch render mode

* Changing the Primitive Bound value

Also worth mentioning, the eyelashes seem to have the same issue too, which are also guide curve based - the peach fuzz and clothing fuzz which are groomable splines are fine, so it must be a guide curve or Arnold issue (since it renders fine with redshift).

This seems like really basic functionality and I'm pulling my hair out here (no pun intended) to get this thing just rendered out. I don't want to have to look into Houdini for grooming but I'm certainly eyeing it up from the sideline at the moment. If anyone could help I'd really appreciate it.

And here is a quick render with everything else hidden of the 4 frames, the first one is fine, the others... not so much

[ratherwilde]

For some reason I can't edit the original post anymore - but I've just tested it works fine in Batch render, but I'm on Maya indie and I'm not paying for a license just for a personal piece turntable when render sequence should work. 

[ratherwilde]

Bumping incase anyone has any ideas!

[BigRoy · Accepted solution]

Are the grooms loaded from a Referenced file? 🙂 If so, it's a known limitation with XGEN. It's because during batch render it opens the scene on the other frame and then initializes the groom with the geo in that position and thus generates the groom in the wrong way. A hack is to go the the 'setup frame' (or at least the frame where the geo is in the original position the groom was created on, reload the reference, and voila. The XGEN re-initializes as if that was the input geo.)

The general solution would be to CACHE the grooms and use the cached data. Since the cache is pregenerated it should be fine on any machine at any time.

The issue/question got posted a couple of times here on Autodesk Forums but I couldn't quickly find them for you. But if you're more interested you could maybe take some time and try to find them. Usually referring to "jittering" in batch mode, etc.

I think the reason it might be working for you in "batch mode" could be that you are batching the render in one go (e.g. all frames running directly after each other as opposed to e.g. running through Deadline Render manager which will render each frame in  batch individually, opening the scene on the 'invalid' frames). It's just a thought. Could that be the case?

[mspeer]

Hi!

I guess you are referring to this thread:

https://forums.autodesk.com/t5/maya-forum/xgen-interactive-render-farm-random-clumping/td-p/7580158