Scale bar
The scale bar is a marking or scale on the edge of a map , a plan or a figure on which the scale is drawn and the real distances are labeled. The scale bar makes it easier to measure on the map and its length should therefore be accurate to at least 0.5 mm.
Another advantage of the scale bar is that a map or image provided with it remains usable even if its size changes. This is because maps or sketches are often reduced in size without the scale designation being corrected accordingly.
A scale bar can - apart from on paper - also be implemented optically or digitally, e.g. B. in the eyepiece of measuring devices as a reticle (also indirectly as the size of a cross mark ) and on digital maps .
Before the middle of the 19th century, scale bars were usually the only scale indication on maps. In extreme cases, up to twenty different scale bars were specified for different lengths.