The challenge of wrinkles for real-time

How Reallusion implemented its Dynamic Wrinkles system into the latest version of Character Creator.

With the release of Reallusion’s Character Creator 4.2, the 3D software maker unleashed its new Dynamic Wrinkles system. This system automatically–and in real-time–generates wrinkles on the face of a digital character via changes in expressions, say from keyframe animation, mocap data or the use of live facial puppeteering apps.

The idea of Dynamic Wrinkles is all about adding that much-needed personality and further realism to the faces of your digital characters, especially human or human-like characters.

A detailed breakdown of how the Dynamic Wrinkles system does this is available on Reallusion’s website, where you’ll see plenty of before/after examples and get a glimpse at what’s going on behind the scenes inside Character Creator and iClone, and how to export the results to tools like Unreal Engine, Unity and Blender.

Here at befores & afters, we wanted to find out the big challenges Reallusion faced in implementing Dynamic Wrinkles. So we asked CEO Charles Chen directly. Here’s his thoughts on what hurdles the team had to get over in crafting a real-time wrinkle shader, enabling wrinkle editing and allowing export to third part tools.

Reallusion has spent time getting the foundations of its digital characters right, including sculpting and skin tools. When it came time for wrinkles, Chen wanted to get that right, too.

“You get a lot of meaning from a character from their smile, their frown, their dimples,” he says. “But wrinkles are super-hard! People smile in totally different ways. We did not want our smiles to look generic.”

The team at Reallusion therefore spent literally years analyzing photogrammetry 3D and 4D scans of actors and stand-ins and their various expressions, to extract wrinkles. Not only wrinkles, but what Chen describes as micro-expressions. “We sampled all these expressions and wrinkle correspondence from the scans, and then built our system to handle all of that.”

The resulting Dynamic Wrinkles system works by implementing wrinkle patterns that accentuate the deep crevices and furrows in the muscles and skin of the face. The expression winkles are materialized with diffuse, normal, and roughness textures. Plus, they’re editable, by going into the textures and customizing specific facial regions in a tool like Photoshop.

Indeed, Reallusion is aimed to give users the highest flexibility possible in controlling wrinkles on their characters, and that includes the control of wrinkle strength in different facial areas.

To allow for that control, Expression Wrinkles are divided into 13 common facial regions that govern the wrinkles lines, crows feet, smile lines, and more. Users can intensify or neutralize any target region of the face, down to the individual channel map like Normals, AO, and Redness.

Remember, too, the wrinkles are designed for real-time 3D characters. Which was another major challenge, and a hurdle that has become even more prevalent given the rise of real-time game engines and other rendering approaches. Since real-time 3D characters are generally optimized to run as efficiently as possible, that often means there are fewer polygons, that is, less detail to deal with. This can be at odds with the desire to show lots of detail, such as via wrinkles.

“We had to figure out a way to blend these diffuse, normal and roughness textures all in real-time in high resolution,” notes Chen. “The only way was of course via a shader. We needed to use whatever ways we could find to squeeze the performance. And then you don’t even feel the frame drop. You don’t even feel a big difference after we implemented this.”

Find out more about Reallusion’s Dynamic Wrinkles system at this special Dynamic Wrinkles site​​.

Brought to you by Reallusion:
This article is part of the befores & afters VFX Insight series. If you’d like to promote your VFX/animation/CG tech or service, you can find out more about the VFX Insight series here.

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