“Leapfrog” is a technique where reference points are measured with the device in one position and then remeasured after the device has been relocated to a new position. A pre-defined target reference system consists of a set of references that are used for relocation. The position of these targets is established by a separate device capable of large volume measurements. Another measurement device can be placed anywhere within reach or line of sight of the pre-defined targets and can locate itself inside the larger reference frame by simply measuring any set of reference points.
Leapfrogging vs. pre-defined targets