MEASURING DEVICE FOR DETERMINING THE SPATIAL POSITION OF AN AUXILIARY MEASURING INSTRUMENT

A positioning method continuously determines the spatial position of an auxiliary measuring instrument having several auxiliary-point markings in a fixed, known spatial distribution relative to one another. Camera images of the auxiliary-point markings are continually recorded using a camera having a surface sensor that includes pixels, and read-out processes are continually performed by reading out the pixels with regard to a respective current exposure value. Image positions of the imaged auxiliary-point markings in the respective current camera image are determined, with which the current spatial position of the auxiliary measuring instrument is derived. Respective current areas of interest on the surface sensor are continually set using image positions determined in at least one previously recorded camera image. The current image positions are determined using exclusively only at most those current exposure values that are received by pixels of the surface sensor lying within the currently set areas of interest.