  Dimensional metrology and positioning operations are used in many fields of
particle accelerator projects. This lecture gives the basic tools to designers
in the field of measure by analysing the spatial layout of measurement systems
since it is central to dimensional metrology as well as positioning operations.
In a second part, a case study dedicated to a synchrotron storage ring is
proposed from the detection of the magnetic centre of quadrupoles to the orbit
definition of the ring.
