An inspection group is proposed for inspecting cylinder-shaped elongated elements for smoking articles, in which a working plane is selected passing through a longitudinal axis of a first elongated element and there are considered a first half space and a second half space arranged on opposite parts with respect to the working plane. The inspecting group includes: a projecting device adapted to project a first stripe of light from the first half space onto an inspection portion of an external surface of the first elongated element and to obtain a first three-dimensional light trace, and also adapted to project a second stripe of light from the second half space onto the inspection portion to obtain a second three-dimensional light trace; an optical assembly adapted to frame the first elongated element and to process a first view and a second view; a processing device adapted to reconstruct a first closed curved section profile of the first elongated element processing an identified first curved light line in the first view and a second identified curved light line in the second view and comparing the first reconstructed closed curved profile with an ideal section profile to identify possible deformations of the reconstructed first closed curved profile with respect to the ideal section profile. The projecting device includes a single projector of a single stripe of light; a shield, arranged between the single projector and the first elongated element, adapted to split the single stripe of light into a first part of a stripe of light and into a second part of a stripe of light; first deflectors of the first part of a stripe of light arranged in the first half space and second deflectors of the second part of the stripe of light arranged in the second half space to obtain respectively the first stripe of light projected from the first half space and the second stripe of light projected from the second half space by a single stripe of light.