Modeling
Modeling
Model fitting
We model faces by fitting a 3D generic face model to a set of images.
We start with a set of 4 or 5 images, all taken simultaneously from
different viewpoints.
The mesh is fitted to the photograph by selecting feature points
on the mesh and specifying where these points should project on the photos.
From these annotations we recover the 3d location of the feature points
and the camera parameters corresponding to the photographs. To deform the
geometry we use a sparse data interpolation technique that deforms the mesh
based on the recovered position of the feature points.
Using these techniques, the mesh can be iteratively adjusted until
we are satisfied with its shape.
To facilitate the annotation process, we use a set
of polylines on the 3D model that corresponds to easily identifiable
facial features. These features can be quickly annotated by outlining
them on the photographs.
Texture extraction
To dress up our 3d face model we extract a texture map from the photos.
The texture is obtained by projecting each of the photographs onto a virtual
cylinder. Using the recovered camera parameters we are able to trace
rays from each point on the face surface back to the image planes. The
different image samples are then combined in a weighted sum to produce the
final texture.
Renderings
(click on pics to get a high-resolution version)
