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Expressions & FACS Scanning

Expression captured by Scan Engine for a FACS rig

FACS 3D scanning

Scanning FACS involves capturing a wide range of facial expressions using photogrammetry techniques, which can then be leveraged to recreate realistic facial deformations for digital characters. However, in order to faithfully replicate a specific facial expression we usually capture it directly in order to provide it ready-to-use.

The Facial Action Coding System (FACS) is a method for anatomically analyzing and deconstructing facial expressions. This theory enables us to construct emotions by combining various facial movements from different parts of the face. In simple terms, the expression of surprise can be represented as a combination of raised eyebrows and an open jaw. This technique is employed in rigging to produce facial expressions in characters that appear more natural and appealing.

FACS and expressions cleaning options

When addressing scanned expressions, we provide several cleaning options.

Expression Wrap Processing

For each expression, our team will meticulously align each expression with then neutral pose. Then with a neutral cleaned model, we wrap the model to fit the desired expression. The loops are meticulously adjusted, and we perform an optical flow analysis to ensure consistent skin deformation in UV space for seamless texture blending. This is a necessary step in order to prepare the model for the creation of blendshapes, delivered in OBJ or Maya format.

Rig Resolution Blendshapes

This cleaning option builds upon the previous one. The result of the wrap is transformed into a blendshape that aligns with the rig’s resolution. FACS textures are applied alongside the neutral textures. We take care of the segmentation of the blendshapes scan and we correct any displacement that might occur, then deliver the result in OBJ or Maya format.

High Poly Resolution Blendshapes

On top of the steps mentioned above, we transfer all the details captured in the scan to a high-polygon version of the model. The scan is conformed to the blendshape, and the skin surface is updated with all the fine details from the expression scan. Additionally, geometric information is baked into textures, including displacement, normal, ambient occlusion, and more, which can be dynamically blended in a shader for enhanced realism. In addition to an OBJ and Maya delivery, we add a Zbrush file including the fine details of the geometry.