Before revision:  To determine boundaries between the semantic components, CSD searches for critical points where the object cross-section substantially changes . CSD then cuts the object at critical points and assigns the same label to those object parts which are along the same sub-skeleton, defining a semantic tubular component.
After revision:  To determine boundaries between the semantic components, CSD searches for critical points where the object cross-section substantially changes . CSD then cuts the object at critical points and assigns the same label to those object parts which are along the same sub-skeleton, thereby constructing a semantic component.