1. A computer-implemented method of processing medical image data, comprising: partitioning image data representative of a plurality of blood vessels into a plurality of sub-volumes; identifying a first voxel corresponding to a relative endpoint of a blood vessel; identifying the blood vessel corresponding to the first voxel based on the sub-volume in which the first voxel is located; and labeling the first voxel with data to identify the first voxel as being part of the blood vessel.