1. A method of determining a position and pose orientation of a physical target object in a scene, said method comprising: using a depth map image capture device to capture a depth map image of the target object in the scene; using a data processing device to implement the following steps: submitting the depth-map image to a first three-dimensional (3D) segmentation process to produce a set of first 3D segments of the same region of the depth-map image; submitting the set of first 3D segments to a second 3D segmentation process different from the first segmentation process, the second 3D segmentation process combining select groups of first 3D segments into combinations of first 3D segments, each combination of first 3D segments defining a 3D segment patch; submitting the segment patches to a third 3D segmentation process different than the first 3D segmentation process and the second 3D segmentation process, the third 3D segmentation process combining select 3D segment patches into combinations of 3D segment patches, each combination of 3D segment patches defining a segment hypothesis; using individual segment hypothesis as masks to isolate corresponding masked regions of the depth-map image; identifying one of the isolated masked regions based on a library of training 3D descriptors; and deriving a position and pose orientation of the target object based at least on the identified masked region.