Blob-Tree Metamorphosis

Implicit surfaces have proved to be a particularly well suited and efficient model for animating and morphing shapes of arbitrary topologies. The Blob-Tree model is characterized as a hierarchical combination of skeletal primitives organized in a tree. The nodes hold blending, boolean and warping operators, which allows the design of complex objects. In this paper, we address the metamorphosis of the Blob-Tree. This appears a difficult task as the tree data-structures of the initial and final shapes are completely different in the general case, and consequently cannot be matched easily. We propose an original technique that solves the correspondence process and creates an intermediate generic Blob-Tree model whose instances interpolate the initial and final shapes. The animator may control the correspondence between features and can specify both the speed of transformation and the trajectory of the nodes and the leaves of the generic Blob-Tree model. This provides him with a tight control over the transformation so as to achieve good visual effects.