A 4-WEEK PROJECT IN Active Shape and Appearance Models by Renée Anderson and Vedrana Andersen

Overview Preprocessing (Renée) Building models (Vedrana) Manipulating faces (Renée) Active appearance models (Vedrana) Tim Cootes

STATISTICAL MODELS Concept Several steps developed by Cootes and Taylor: Data capture and representation Data normalization Statistical analysis

For each object (face, heart, spine): Image Landmark points PREPROCESSING Data For each object (face, heart, spine): Image Landmark points Faces, hearts, spines

PREPROCESSING Cropping and Translation Cropping out the background Center of gravity of landmark points in the center of image

PREPROCESSING Alignment Allowed transformations: translation, rotation and scaling Iterative method: aligning each shape with mean shape

PREPROCESSING Masking For visualization Leave inside of convex hull of landmark points

PREPROCESSING Warping Mapping landmark points to mean shape Tried two - piecewise linear - thin-plate spline

PREPROCESSING Gray-level Normalization Applying scaling and offset to gray-level vectors (samples) Iterative method: normalizing each gray-level vector with mean gray-level

BUILDING THE MODELS Normalized Data Each object contributes with: Landmark points, aligned Shape-free patch, normalized Statistical analysis (PCA)

BUILDING THE MODELS Principal Component Analysis Objects (shapes, gray-levels) as vectors: Distribution of s points in n- dimensional space Alternative coordinate system: - no correlations - sorted coordinates

BUILDING THE MODELS Principal Component Analysis Method: finding eigenvectors and eigenvalues of the covariance matrix Linear model:

BUILDING THE MODELS Shape Model Shape vector: Model:

BUILDING THE MODELS Gray-level Model Gray-level vector: samples of gray values Model:

BUILDING THE MODELS Appearance Model Appearance vector: Model:

BUILDING THE MODELS All Faces – Modes of Variation First mode Second mode Third mode

BUILDING THE MODELS Neutral - Appearance Variation Changing the first three modes of variation simultaneously

BUILDING THE MODELS Hearts - Appearance Variation Changing the first three modes of variation simultaneously

MANIPULATING FACES Reconstruction

MANIPULATING FACES Caricatures

MANIPULATING FACES Forced Smiles

ACTIVE APPEARANCE MODELS Concept Search – optimization to minimize Learning – estimating A Iterative model refinement

Thank you!