Wild Optical Distance Measuring - brochure

detailed brochure from Wild Heerbrugg about Optical Distance Measuring

Content:

In surveying, optical distance measurement is generally called Tacheometry. The word tacheometry is of greek origin meaning quick measurement. The most important advantage of the tacheometric method rests in the possibility of measuring a distance between two points without having to go over the ground.

Compared with the chain, tape or rod measurement, this means a considerable time- saving. ln tacheometry a theodolite is always set up at one end-point (station point) and a staff at the other end (target point) of the di stance to be measured. The staff is the measuring-unit for the distance. Rangefinders built for military purposes do not fall under tacheometers. They are comparatively rarely used for field-surveying, being more suitable only for measurements of distances over 200 m length. The difference between the two methods lies in the fact, that for military rangefinders no staff has to be set up at the targetpoint, the instrument itself being developed as a base of constant length giving the measuring unit for the distance.

Du ring the past 100 years a great number of various types of tacheometers have been developed, most of which have only a historical interest.

Nowadays the tacheometers commonly used, - disregarding the military rangefinders and some other special constructions, - may fundamentally be classified under 3 different groups:

I. Tacheometers with the subtense-bar at the target point.

II. Tacheometers with the measuring-staff at the target point and the measuring-device inside the telescope of the theodolite.

III. Tacheometers with the measuring-staff at the target point and the measuring-device in front of the telescope.