1. A non-transitory computer-readable medium including instructions executable by a processor to perform a method, the method comprising: providing an edge-detected data set of that represents a surface boundary of a three-dimensional generally tubular structure according to a three-dimensional voxel data set for the tubular structure; computing a gradient vector field of a distance transformation for the edge-detected data set; computing a scalar derivative of each voxel in the gradient vector field relative to adjacent voxels to provide a derivative field for the voxels in the edge-detected data set, wherein the derivative field identifies a rate at which each voxel is changing direction; thresholding the derivative field of the voxels to identify a voxel data set that includes a plurality of contiguous voxels where the gradient vector field changes rapidly, according to the computed derivative, the plurality of contiguous voxels defining a continuous centerline of the tubular structure, the identified voxel data set being stored in memory to define the centerline of the tubular structure; and generating a model that parameterizes the centerline of the tubular structure in a three-dimensional coordinate system based on the voxel data set that includes the plurality of contiguous voxels.