Abstract: The present invention relates to an apparatus and a method for generating a cloud of points (1A) representative of the real outer shape of a human transportation vehicle (1) located in a building (4) and for determining the position and orientation of said human transportation vehicle (1) in said building (4) and for determining the relative position and orientation of at least one movable work platform (2), the position and orientation of said human transportation vehicle (1) and the position and orientation of said movable work platform (2) being referenced with respect to at least one known building (4) reference point (R1), said apparatus being for preventing collisions between the movable work platform (2) and the human transportation vehicle (1), said apparatus comprising: at least one known building reference point (R1) being the origin point of a 6 degrees of freedom coordinate system and serving as a central common reference point, and at least one three-dimensional scanning means (3) for determin