3.4 Shape Library
The system maintains a shape library that contains the shapes
learned so far. The system can load a directory of shape files and
learn them. The user can also teach the system new shapes at
runtime, for example by sketching. To teach the system a new
shape, the user presents it to the camera in a frontal view. The
system then analyzes the shape contour and adds it to the shape
library. The user can now attach a virtual model to be augmented
to the new shape and set its different properties, such as scale and
rotation.
When teaching the system a new shape, the image goes through
the same recognition step described in the Shape Recognition
Section, and its signatures are hashed. The curve, its signatures,
and additional required information are stored in the shape library.
These are later used in the recognition step in real-time. Since we
use shape contours, the system works for curves and solid blobs in
the same manner. For curves, double edges can be detected and
inner edges ignored in order to perform recognition and tracking
according to outer edges.