FaceGen SDK Manual - Overview

The Face Coordinate

All faces in FaceGen are represented by a face coordinate and an optional "detail texture" modulation map.

A face coordinate is 130 signed floating point numbers, in standard deviations, usually in the range [-5,5]. 50 of these numbers describe symmetric shape, 30 describe shape asymmetry, and 50 describe color (always symmetric). The set of possible face coordinates is "face space".

A detail texture, if present, is a JPEG encoding of the ratio of the photograph color channel value to that generated by the face coordinate. A value of 64 correponds and the ratio varies linearly.

The face coordinate and detail texture (if present) are stored in the .FG file format.

There is no mesh-specific data in an FG file. An FG file can be applied to any mesh and UV layout for which statistical data has been created. Statistical data is created for a mesh or color map using the 'fg3t' tool.

Statistical Appearance Models

A statistical shape model (SSM) is required for each mesh whose shape will change with head shape.

A statistical color model (SCM) is required for each color map containing skin.

A statistical appearance model (SAM) is made up of an SSM and one or more SCMs for its maps.

A SSM consists of a mesh file containing the base geometry, and a .EGM file containing the statistical data.

A SCM consists of an image file containing the base color map, a .EGT file containing the statistical data, and for maps containing the face area, a .FIM file defining the image resampling from the FaceGen internal UV layout in the .FG file to the UV layout of the mesh, and used for transforming the detail texture.

Data Flow

Create a face (.FG file) from a photo:

Create a random face or modify a face with FaceGen controls:

Interactive deformation:

Construct a mesh from a face:

Apply an animation morph defined by a mesh:

The construction and morphing processes are repeated for each SAM in a model set, using the same face coordinate and morph co-efficients (where applicable).