Xgen in VFX/film production workflow?

#1

The studio im working for is lookng into an alternative to Yeti. And seriously considering using Xgen in production. Btw we are using Vray as Our primary renderer and running maya 2016 atm
I have been doing some research of my own, found some pros and cons. But still unclear on a few things. I was hoping to get some input here on this thread. Thanks

  1. Does Xgen work with Character with displacements ? If so how is it setup?
  2. How to Handle simulation with Xgen?
  3. Since Maya currently doesn’t support UDIMs for the artisan tools for painting Density and Regions maps. How to workaround that limitation?
#2
  1. Does Xgen work with Character with displacements ? If so how is it setup?
    Yes, XGen can work on characters uing displacement maps. The Maps being used to displace the character geo can be used as the basis for displacement maps in XGen, under the Displacement section on the primitives tab in the XGen UI

XGen Displacement

Xgen Displacement2

  1. How to Handle simulation with Xgen?
    By default in Maya, nHair is used as the basis for simulation, via Guide Animation or Animwire or Control Wire modifiers where you create a nHair system and the output curves are attached to drive the deformation of the guides or primitives.

Animating XGen Hair

  1. Since Maya currently doesn’t support UDIMs for the artisan tools for painting Density and Regions maps. How to workaround that limitation?

Use Mudbox or Mari as they support painting in UDIMs. The 3D paint tool is outdated, to say the least and is in dire need of an overhaul

Cheers

#3

Toddski: thank you for your explanation. I think i have a better understanding now. So I assume Xgen accepts UDIM/UVTILE maps without having to convert to ptex. I was under the impression that Xgen only works with Ptex. If Xgen does support UDIM, it would clear some of my worries then.

In regards to animating Xgen Hair, From what I can understand, Theres 2 ways of doing this with the nhair system.

  1. create Curves with Cp curve tool or Paint effects to Curves >Use them as Nhair and guides OR
  2. Create Xgen guides > then convert them to curves and create Nhair system.

Am I correct ?

#4

XGen does only work with Ptex. Regular texture files can be converte to ptex but internally, XGen only uses ptex maps so it’s best to use a paint tool that can export ptex maps if you need to paint in UDIMs

The Guide animation and Animwire modifier can create the nHair system from the guides or by sampling the groom primitives and creates curves and the ndynamic system. also, curves can be derived from guides (and primitives via the MEL export) and used in a simulation package outside of Maya and then cached. The cache can be used to drive the guide animation or animwire modifier

#5

Thanks for the speedy reply Toddski! Thats unfortunate. Because our pipeline at work is built around UDIM textures. Its seems that a feasible workaround is to make a Hair cap that wraps to the Character. I hope UDIM gets supported one day for Xgen.

#6

ptex does not need UV’s so UDIMs don’t apply.

Using a scalp mesh wrapped to the character is a recommended practice as that way, any topology changes to the head mesh need not affect the groom as ptex does not like topology changes. The scalp mesh does not need to be rendered and can be part of the character rig so that exported XGen collections can be easily imported into scenes to rebuild the collection on the geo.

The newer Interactive Grooming System supports UDIM textures and does not need ptex maps.