Creatures in VFX: Skin Binding and Skin Simulation

July 23, 2017

 

 

Today I would like to discuss the creation of our Muscle Body Rig, focusing on how the internal structure drives the skin.

We will talk through different approaches and technologies like Maya Muscle Skin Deformer, nCloth, and also something newer like Ziva VFX.

 

The bigger vision is something you can get by attending multiple CG/VFX events and talking with students and VFX veterans.  

What do they use? What would they like to use? What is their vision for the future of the Muscle Systems and Skin Deformers? 

I would like to write down my thoughts about this topic

 

 

 

  • Maya muscle & Maya Muscle skin deformer (Skin wrap binding approach)

 

Maya muscles and the Maya skin deformer are two technologies that almost all of us know or used. Without a doubt, they defined a standard in the past. Nowadays, in my opinion, they are considered a little bit "old".

 

Using the Maya skin deformer or any other wrap closest point has for sure some positive aspect compared to an nCloth Solver approach. It's solid and just in rare cases the skin is breaking or exploding, because we don't have any simulation involved.

 

Depending on how far we would like to push our creature, a nice set of correctives are required, and also an nCloth layer on top could help to add more realism and a more organic feeling. 

 

 

 

 

 

  • nCloth skin simulation (pseudo-physical solver approach)

 

To use nCloth or proprietary solver to drive the skin is for sure a newer method. We have fewer limitations and thanks to the skin solver we are able to propagate even more details of the underneath anatomy to the skin: secondary motion, wrinkles, self-collisions and so on.

 

It requires more time to set up because it has all the maps/attributes for the simulation, calculated frame by frame with all the related limitations. 

With the nCloth approach, we are not using the large set of corrective shapes that we used in the past (Skin Binding approach).

 



It’s important to remember that at the end of the day, nCloth was developed as a general purpose tool to do cloth materials. It has some helpful features that can be appropriated to do muscle and skin work, but will never be a complete, purpose-built solution to this problem. 

 

 

 

 

  • Ziva Tissue/Cloth Simulation (fully-physical solver approach)

 

Ziva Dynamics is an innovative company changing how virtual humans and creatures are created. They developed ZIVA VFX for Maya that allows you to create and simulate interdependent muscles, skeletal, and tissue networks that mimic anatomy.

 

 

 

They harness the Finite Element Method (FEM) to produce complex, physically faithful, organic tissue deformation. 

In the new Ziva ver. 1.0, they have a cloth solver, specifically designed for simulating fascia and skin in realistic ways.

 

 

 

  • Conclusion:

 

In conclusion, I think we should put even more effort to invest in the nCloth solving method, I'm sure in a couple of years it will be more advanced and able to produce extra realistic results.  

 

Realistic results can be achieved by drawing on physical simulations and allowing those algorithms to do the heavy-lifting for us as Technical Directors. As systems become more advanced, speed barriers are disappearing, and as physical solvers get smarter, the future is bright for creature FX.  

 

 

If you are a student, I would like to suggest to play with the Maya Muscle and the Maya skin deformer just to be familiar and to understand pros and cons. nCloth will be the next step, it's a big engine that can be used to deform in a more realistic way our digital skin, in the meantime keep an eye on ZIVA VFX for Maya and their tissue and cloth solver.  They also have an 180-day non-commercial license you can play around with for free. 

 

This path will allow you to play with different tools, to experiment new workflows and to improve your anatomy skills.

 

Thanks for your time and ROCK ON!

 

 

 

 

Special thanks to Andy Van Straten (Senior Creature TD at Ziva Dynamics) and Erica Vigilante (Lead Creature FX at Framestore) who helped and contributed to making this insight a cool insight! ;)

 

 

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© 2018 by William Gabriele

 

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