deriving an endoscopy voxel dataset by using an endoscopy protocol;

starting with an initial voxel in said dataset, labeling voxels neighboring said initial voxel with a first label number of a series of consecutively increasing label numbers;

labeling voxels neighboring respective ones of said voxels having said first label number with a second label number of said series;

repeating the foregoing step by labeling with progressively higher label numbers those voxels neighboring voxels numbered in said foregoing step, until an endpoint is reached with voxels having a highest label number;

starting at a first voxel with said highest label number, searching for a neighboring second voxel with a smaller label number than said first voxel and storing the location thereof;

starting at said second voxel, searching for a neighboring third voxel with a smaller label number than said second voxel and storing the location thereof;

repeating the foregoing step until said initial voxel is reached, thereby establishing an initial path through said image between said initial and said first voxel;

smoothing said initial path to result in an intermediate path, said intermediate path exhibiting plurality of vertices;

centering on a first vertex, a sphere exhibiting a maximal diameter short of contacting said boundary walls;

centering on further vertices, further respective spheres exhibiting respective maximal diameters short of contacting said boundary wall; and forming a centered path by consecutively joining centers of said spheres;

wherein the above steps is performed by a digital computer.