The space-time map applied to Drosophila embryogenesis
Many physical phenomena have complex structure in both space and time. To systematically understand these phenomena from images one needs representations that unify the treatment of space and time. The authors create such a representation, the space-time map, for characterizing contour evolutions. Many types of information are computed and stored as facets of the map, registered to a space-time manifold generated by the evolution. The authors demonstrate their representation on the example of Drosophila embryogenesis in optical section. Changes in embryo shape are reflected as changes in the dye distribution along the deforming vitelline membrane contour. The authors extract a series of contours and create a two-dimensional space-time map. They track intensity on this map to obtain a velocity field. They extract space-time ridges and significant motions on this map, and use them along with prior knowledge to recognize the significant features and events of embryogenesis.