To measure the dimensions of a tubular vessel, it is planned to plot a set of wall lines on the surface of the vessels. Then, the lengths of these wall lines are measured between a starting section and an arrival section. The plotting of the wall lines starts from a central line of the vessel divided into segments. For each central line segment, a wall line segment is defined on the wall by intersection of a plane containing this central line segment and intersecting this wall. Other wall line segments are distributed all around and all along the wall. Then, the lengths are measured.