Contouring in 2D while viewing stereoscopic 3D volumes

The ability to manually specify contours in a volumetric data is often required in situations when automatic algorithms are unable to accurately extract the desire volume. Conventionally, the contours are drawn over a slice, working on plane-by-plane basis usually constrained to orthogonal planes. In defining the contour on a 2D image, the user faces the problem of loosing 3D context (does the tissue belong to inside the contour or outside?). This requires the constant back and forth movement from a plane view where the interaction takes place (usually with the mouse) to the 3D volumetric view that provides the contextual information. We present an interactive environment that allows for efficient contouring while providing contextual 3D information to the user.