topic Re: Xgen popping when sequence rendered in Arnold in Maya Forum

Xgen popping when sequence rendered in Arnold

Anonymous — Mon, 23 Jan 2017 17:57:00 GMT

I've been having a problem with rendering a sequence of xgen groomable splines where the xgen looks to be regenerating each frame, creating a lot of noise around the fur. I'm using render sequence with Arnold in Maya 2017, I've set the primitives to generate from my baked XPD file and I've exported patches for batch rendering and ticked Arnold's 'use aux render patch' option and pointed it towards the .abc file for the scene patches. I've used the modifiers, cut, noise, clumping and bakedGroomManager.

I've tried testing this in a scene with just the geometry that the xgen is bound to and two lights. Nothing is referenced. This error keeps occuring:

// Error: line 1: XGen: Error in expression "XG_RENDER_:Character01_description::arnold_auxRenderPatch". [E:/Dropbox/Project_name/PILOT/3D/maya/assets/characters/Character01/character01_xgen/Character_bodyXgen.006.012__Ti01_collection.abc]

Error: Syntax error near ':':

E:/Dropbox/Project_name... //

I've tried not setting a path for the Auxilary Render Patch option but the popping/noise still happens. I'd be very grateful if anyone had suggestions on how to fix this problem.

This is a one sec video of an example of the problem. It's difficult to see unless you go through frame by frame.

https://youtu.be/_viQ7lDRwDg

Re: Xgen popping when sequence rendered in Arnold

Michael_Todd — Tue, 24 Jan 2017 17:59:03 GMT

My first guess would an expression somehwere that is using $P. Replace $P with $Pref or $Prefg, this should help stop noise and popping. Also make sure the mesh has the xgen_pref attr.

Cheers

Re: Xgen popping when sequence rendered in Arnold

Anonymous — Wed, 25 Jan 2017 13:33:34 GMT

Thanks for your reply Michael.

I've made a new scene with only the groomable splines on a sphere, a BakedGroomManager in the modifiers and no expressions. The patches are exported and the colour is controlled by aiHair root and tip colour sliders but the noise is still there when I render sequence. I'm only a beginner with XGen so there might be an expression that I'm missing out on somewhere. Also, how do I check if the mesh has the xgen_pref attr? Could you have a look at this project with the xgen sphere please?

https://drive.google.com/drive/folders/0B48pgEU28iXoX3Bha0I0XzZDODg?usp=sharing

Re: Xgen popping when sequence rendered in Arnold

Michael_Todd — Wed, 25 Jan 2017 15:23:08 GMT

I'll take a look when I get a chance but I have a question, are you talking about noise in the image or noise in the motion?

cheers

Re: Xgen popping when sequence rendered in Arnold

Anonymous — Wed, 25 Jan 2017 18:21:42 GMT

It looks to me like noise/movement in groom even if the object is stationary. I tried rendering with higher Arnold samples in case I was mistaking it for noise in the shadows but it still looks like the hairs are moving.

Re: Xgen popping when sequence rendered in Arnold

Michael_Todd — Wed, 25 Jan 2017 18:52:05 GMT

Does it move in the VP in playblasts?

Re: Xgen popping when sequence rendered in Arnold

Michael_Todd — Wed, 25 Jan 2017 21:13:11 GMT

Looking at the scene, I don't see any motion in XGen in the VP and I suspect the apparent noise is due to low sampling in Arnold. Indirect lighting can be very noisy and requires pretty high sampling values to smooth it out.

also, you might want to check your aiHair shader settings and up the indirect diffuse or it will look darker under the physical sky light.

Cheers

Re: Xgen popping when sequence rendered in Arnold

mspeer — Thu, 26 Jan 2017 03:12:21 GMT

Hi!

If you are not sure if it's aa noise you could try rendering with "Lock Sampling Pattern" enabled, in Render Settings -> Arnold Renderer -> Sampling.

https://support.solidangle.com/display/AFMUG/Samples#Samples-LockSamplingPattern

Re: Xgen popping when sequence rendered in Arnold

Anonymous — Thu, 26 Jan 2017 21:31:52 GMT

Thanks so much for looking into this for me! I had discounted sampling as the problem but I must just not have tested it with high enough values. There's no movement on my end either in a playblast and there's no movement or noise when I render a sequence zoomed into the mesh. I've left a sequence rendering at the office over night with higher samples so I'll know for sure in the morning.

Thank you also for your suggestion mspeer. I'll try this too.

Re: Xgen popping when sequence rendered in Arnold

Anonymous — Fri, 27 Jan 2017 09:21:10 GMT

The results are a lot better now. Many thanks for taking the time to look at this!

Natasha