Two-dimensional implementations

The first implementations of the model were coded in the PostScript 2D imaging language, [7] and rendered as monochrome line art.

 
Figure 1: An illustration of the early two-dimensional facial model.

The original model consisted of seven real-valued parameters; these were:

eyebrows

Determines whether or not the eyebrows are raised. Valid values are from -1.0 (pressed downwards fully) to 1.0 (raised fully).

eye x

Gives the horizontal offset of the pupils in the eyes from the centre.

eye y

Gives the vertical offset of the pupils in the eyes from the centre.

eye closure

Gives the degree to which the eyes are closed; 0.0 means that they are wide open, and 1.0 means that they are completely closed.

smile

Gives the degree to which the mouth is smiling; 0.0 indicates a complete frown, and 1.0 an emphatic smile. 0.5 is a neutral expression.

mouth open

Gives the degree to which the mouth is open; 0.0 means that it is completely closed; 1.0 means that it is wide open.

mouth scale

Gives the scale of the mouth, as drawn on the face. 1.0 is full width; smaller scales may indicate pursed lips or similar configurations.

This model was later updated, and three additional parameters were added, representing the angle of the face on the X, Y and Z axes, the eye coordinate specifiers were replaced with specifiers in polar coordinates (the direction of the eye and the angle), as these are more natural for expressing the direction of the gaze) and the model was expanded, with the parameters for the eyes and eyebrows being duplicated to allow each side of the face to be independent.