(*e.g.* floors, doors, walls, tables etc.) and outdoor (*e.g.* mountains, valleys, hills etc.) environments. It is hence observed that a method for exploiting the information of structural information in 3D is very much needed in order to improve the quality of localization achieved.

In this paper, we particularly study the scenario where there is an emergency inside a building, such as fire, earthquake, hostage situation etc. When the members of a search and rescue team have limited time, our work aims to utilize wireless sensor networks to release the burden of searching, and allowing team to go for rescuing.

Suppose that the wireless nodes are deployed onto the corridors of a building. Each corridor can be interpreted as a collinear group (i.e. hyperplanar group in 2D). Moreover, since the building probably has multiple floors, each floor is a coplanar group (i.e. hyperplanar group in 3D).

In Figure \[fig:deployment\], we give an example of a network deployed onto the corridors of a three-floor building. The dots denote the wireless nodes inside the building, and colored rectangles denote three different floors. A pair of nodes denoted by the same color sit on the same floor.

\[ axis on top, view=[-30]{}[-15]{} \] 3\[draw=none, 